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CASE STUDIES ON KETs MARINE APPLICATIONS
CASE 5
MICROELECTROMECHANICAL SYSTEMS (MEMS)
Copyright © 2019 IDONIAL Technology Center
Index1. INTRODUCTION........................................................................................................................3
2. CONTEXT OF THIS DOCUMENT..............................................................................................4
3. METHODOLOGY........................................................................................................................5
4. MICRO & NAOELECTRONICS KET OVERVIEW......................................................................5
4.1. Definition of Microelectronics and Nanoelectronics.............................................................5
4.2. Brief Review of Electronics Evolution..................................................................................5
4.3. Silicon Based Electronic Technology Limits........................................................................7
4.4. Alternatives to Silicon..........................................................................................................8
4.5. The Value of Technological Development in the Field of Electronics..................................9
4.6. Beyond Electronics..............................................................................................................9
5. EU STRATEGY ON MICRO AND NANOELECTRONICS........................................................13
6. MEMS APPLICATIONS IN THE MARINE AND MARITIME FIELDS.......................................14
6.1. Illustrative Examples: Gyroscopes and Accelerometers....................................................14
6.2. General Applications of MEMS in Marine and Maritime Applications................................15
6.3. Outstanding MEMs Applications in Marine and Maritime Fields.......................................16
7. LOOKING TO PATENTS TO MEASURE MEMS RELEVANCE...............................................23
8. CONCLUSIONS........................................................................................................................26
9. ANNEX: Representative MEMS Marine Applications Patents..................................................27
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1. INTRODUCTIONWith a good adjustment to the famous Moore's law1, electronic technology has been evolving in recent decades at a high speed, as for example, a person who is approaching 50 years old, has been able to observe (although this person may be not fully aware of this fact) how the silicon-based electronic technology has moved from housing a transistor2 in one hundredth of a millimeter, to requiring only 7 nanometers by the end of 2018, a reduction factor greater than 1.400 times from the original size. The consequences of this impressive advance are palpable in our society, and in this same period of time we have been able to see really notable results through time: calculators, portable electronic devices, personal microcomputers, mobile telephony, embebible electronics, flexible electronics, optoelectronics, electromechanics, etc.
All these advances have been possible thanks to different developments:
- Increasingly reduced scale of work for electronic design and manufacturing. This development strategy is commonly called "more Moore", as this evolution fits this "law" predictions pretty well.
- The evolution at the level of electronic architectures3 based on silicon. This development strategy is commonly called "more than Moore", as it proposes an evolution not only based on a progressive miniaturization (and the exponential increase of calculation power), but alternative models and architectures of computation
- The exploration of alternative concepts not based on silicon. This development strategy is commonly called "beyond CMOS", for proposing alternatives capable of transcending the known limits of silicon in terms of potential performance.
All of these strategies have exponentially increased the processing power of chips, reduced the electrical consumption, and in general have given rise to a whole generation of applications and devices that are possible thanks to advances in the field traditionally called "microelectronics", or even "nanoelectronics" in our days.
It is therefore obvious that both microelectronics and nanoelectronics are absolutely critical technologies for the technical evolution of any sector in the coming years, and that is why they have been recognized as a "key Enabling Technology" by the European Commission.
1 Moore´s Law: this “law” (stated by Gordon Moore), states that overall processing power will doublé every two years.
2 Transistor: semiconductor device that can amplify or swicht an electric signal
3 The monoprocessor systems have given rise in the last decades to more complex systems, multi-core and multi-thread, capable of implementing the principles of parallel computing on commercial and affordable hardware.
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2. CONTEXT OF THIS DOCUMENT
The present document constitutes a deliverable in the framework of the KETmaritime project “Transfer of Key Enabling Technologies (KETs) to the Maritime Industries”. This document is the result of the activities performed within the Action number 3 “Scientifical and Technical Analysis: State of the Art and technology trends revision”, within the framework of WorkPackage 5 (WP5), titled “Mapping of R&D ecosystem”. Action number 3 is intended to generate five case studies related to a KET – sector/subsector combination. For each case, a technology study is performed by searching information in existing reports, scientific publications and patent databases in order to determine current state of technologies, stakeholders, technology trends, etc. The five case studies selected are shown in the next table:
Table 1: KETmaritime case studies – Scientific and Technical analysis (WP5, Action 3)
ID KET Title
1 Advanced Manufacturing Advanced Manufacturing Shipbuilding Applications
2 Nanotechnology Nanotechnology Marine Applications
3 Industrial Biotechnology Marine Industrial Biotechnology
4 Photonics Photonics Marine Applications
5 Micro and Nanoelectronics Microelectromechanical Systems (MEMS) Marine Applications
This document is related to Case Study 5 – Microelectromechanical Systems (MEMS) Marine Applications.
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3. METHODOLOGYThis document will address the previously presented subject through the following sections:
- Micro and nanoelectronics Key Enabling Technology overview : brief description of the technology and its basic principles, also providing information about general applications. An overview of European Strategies for R&D related to this KET is as well provided.
- Micro and nanoelectronics applications : a state of the art addressing applications of this KET in marine environments.
- Brief study of patents in the field of Micro and Nanoelectronics.
- Final conclusions : summary and highlights of the document.
4. MICRO & NAOELECTRONICS KET OVERVIEWAlthough in the introduction chapter we have already pointed out some of the concepts that are basic in the field of electronics, throughout this section we will try to provide a general perspective over this subject, in order to make visible its capacity as a driver for technological development.
4.1. Definition of Microelectronics and NanoelectronicsEssentially, and even if referring to different sources it is possible to obtain "canonical" definitions of both microeletronics and nanoelectronics, in a simple way they are both part of a global concept, which includes the set of rules of design, materials and manufacturing processes that allow the human being to develop complex miniaturized electronic systems, applying the micro- and nano-prefixes according to the scales in which it is possible to manipulate the basic components that give rise to them.
In this way, it is common that the terms electronic, microelectronic and nanoelectronic can often overlap, fundamentally because they are concepts that are the result of a natural evolution over the original concept, showing a path of an evolution towards greater miniaturization ratios, as a way to increase the capacity of electronic systems. That is why, from this moment on, we will some times use the "electronics" concept in a general way, considering that the modern meaning of the concept already contains the micro- and nano- concepts in itself.
4.2. Brief Review of Electronics EvolutionBoth current electronics and the electronics developed over the last 50 years are based on what is often called "silicon technology". To understand why silicon has been the basis of this evolution, it is necessary to explain a series of basic concepts:
- Current electronic technology is based on the use of semiconductors. As is well known, electronic devices are electric devices capable of using said electrical current to perform
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computing functions. This being its basis, it could be thought that any metal could be a good "candidate" for the manufacture of electronic devices, but its condition as "pure" conductors means that the electric current can not be modulated (except by direct mechanical action on them), so it is necessary that the material present semiconductor characteristics, that is, that the passage of the electric current through it can be modulated.
- Semiconductors are elements of the periodic table known as "metalloids" or "semimetals", because they have properties halfway between metals and non-metals. Thus, elements such as silicon, gallium or gallium arsenide are some of the best known semiconductors, but there are also organic semiconductors.
An additional peculiarity of semiconductors is that their behavior can be modified in a relatively simple way through a process of "doping" that, adding impurities to them, modifyes their electrical behavior, altering the number of free electrons and " "free holes” for these electrons movement.
- Silicon has emerged as a fundamental semiconductor due to three fundamental reasons: it is very abundant on Earth (it is also in the universe) and therefore cheap, it has a great resistance to high temperature, and is additionally easily aleable.
Thus, current silicon technology is based on the use of semiconductors, which are the basis for the design and manufacture of the vast majority of electronic architectures used in the last half century.
Though this document´s goal is far from addressing complex electronics concepts for the non-versed in the subject, it is necessary to tackle a referential concept in the field of electronics (which is key to understanding the evolution to date), the transistor. In a very basic way, a transistor is an element capable of controlling/modulating the flow of electrical current, through a semiconductor substrate, two terminals through which the current enters and exits, and a third terminal that modulates the passage of current between the previous two. This structure, nowadays simple, contributes to the transistor ability to behave in three different ways, allowing all the current to pass through, allowing the passing of variable current levels, or not letting any current pass through. This behavior is in a basic way the origin of the binary language, in which the pass or blocking of current trough the transistor is interpreted as a “1” or a “0”, in such a way that it can be said that the concept of transistor is the one that by itself gives way not only to modern electronics, but to the current concepts of computing and programming, without which it is impossible to understand current technology.
Figure 1: Transistor. Image4 public under Pixabay Licence.
4 https://pixabay.com/es/photos/transistor-bd-135-electr%C3%B3nica-903642/
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The invention of the transistor and the subsequent combination of this element with capacitors and resistors (which expand the modulation capacity to the passage of electric current) give rise to the concept of integrated circuit or chip, from which all the modern electronics arises, in which the successive miniaturization of the previous components has allowed humanity to develop technology on a micrometric scale (10-6 meters) and even on a nanometric scale (10-9 meters).
Figure 2: Micro Processor. Image5 public under Pixabay Licence / Raspeberry Pi 3B. Image6 public under Pixabay Licence
In this way, practically all electronic developments up to date have been possible so far thanks to the continuous miniaturization of electronic components, in a linear progression since the 70s, period in which electronic technology has been able to duplicate its performance in short time periods (historically the rhythm has ranged form 1 to 2 years), doubling the number of transistors housed in a microprocessor, thanks to the reduction in the size of them. This was predicted by Gordon Moore7 in 1965, who, following the advances that were being made at that time, predicted that the power of computers would double every 24 months. While the pace of this duplication has presented certain variations, the evolution in this area has been adjusted so far in a reasonable manner to what was predicted by Moore, which makes that today, this fact, currently known as "Moore's Law", is in a certain way a reference for marking the expected pace for the evolution of the current technology based on silicon semiconductors.
4.3. Silicon Based Electronic Technology LimitsAlthough, based on the above, semiconductors have been a fundamental part of the development of electronics to this day, the miniaturization capabilities based on this technology are apparently approaching their limits. At present, modern technology reached by the end of 2018 the barrier of 7 nm8 (capacity to accommodate a transistor in that space), in the present year 2019 some of the main players in the sector are already performing tests in the scale of 5 nm9 (commercialization is
5 https://pixabay.com/es/photos/procesador-micro-tecnolog%C3%ADa-4161470/
6 https://pixabay.com/es/photos/dispositivo-la-raspberry-pi-pc-3438525/
7 Gordon Moore: Co-founder (1968) of Intel Corporation, one of the world´s highest valued semiconductor chip manufacturers
8 “AMD Beats Intel, Nvidia to 7 nm”. Electronic Engineering Times. November 2018.
https://www.eetimes.com/document.asp?doc_id=1333944#
9 “TSMC will be mass producing 5nm chips next year, 5nm+ in the works”. GSM Arena. May 2019.
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planned for 2020), and it is expected that these limits will be reached after achieving 3 nm10 technology (planned to be commercialized in 2022). These advances are being complemented with additional developments, such as the concept of "3D transistors" that introduced at the beginning of this decade have been the perfect complement to increase the density of transistors of the chips, all of which are key again for the technology that we enjoy nowadays.
This "race" for the miniaturization and the increase in transistors "density" results in progressively more powerful and efficient chips, and although the physical limit of silicon-based technology has not yet been reached (in fact, those that were thought to be the limits a few years ago, have been widely exceeded nowadays), the R&D costs associated with each leap in scale are increasingly higher, and there is some debate no longer about the ability to miniaturize above of current capabilities, but around the profitability of doing so11. In this way, it is possible that although it is feasible that at least in the next decade we will continue to see advances related to this technology, its limits seem to be drawn more or less clearly. In fact, some of those limits were already reached in a practical way more than a decade ago, in which the microprocessor market attended the end of the "MHz12race”, and the era of commercial multi-core and multi-thread microprocessor technology was opened. In a basic way, at that time, higher "clock speeds" were hard to be risen for commercial-type hardware, reaching limits where it was difficult to increase the power of a processor based on the increase in its speed, due to limitations in terms of generation and dissipation of heat, as well as electricity consumption.
4.4. Alternatives to SiliconFor many years13, the end of the "silicon era" has been conjectured, although it is true that, as a general rule, a large part of the limit values that were thought to exist have been passed down to date. Not only the advances in miniaturization, but the same advances in the architecture of the chips have allowed to continue increasing in a more or less linear rate their performance, reducing their consumption at the same time. Today, and despite the fact that the physical limits of silicon exist (it will not be possible to miniaturize manufacturing processes or increase the density of transistors below the atomic radius of silicon itself), it is difficult to say when the present era will end.
https://www.gsmarena.com/tsmc_will_be_mass_producing_5nm_chips_next_year_5nm_in_the_works-news-36971.php
10 “Samsung Unveils 3nm Gate-all-around Design Tools”. ExtremTech. May 2019. https://www.extremetech.com/computing/291507-samsung-unveils-3nm-gate-all-around-design-tools
11 “2NM manufacturing process is possible but not profitable”. Zax Times. March 2018. https://www.zaxtimes.com/2nm-manufacturing-process-is-possible-but-not-profitable-844/
12 MHz and GHz are frequency units used for measuring “clock speed” of chips. Given a same chip arquitechture, more clock speed implies more processing power per time unit.
13 “The Limits of Silicon”. 1978. https://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=1646920
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Different alternatives for the future have been postulated, perhaps most well known being quantum computing14, and since the last decade the omnipresent graphene15. Although the theoretical capabilities could greatly improve in some aspects the silicon, current limitations (for example, graphene is a conductor, and not a semiconductor) make it not prudent to think that in the short or medium term these can be real alternatives to replace a technology as widespread as the one that today is enabled by silicon. However, perhaps the most plausible alternatives are to be found in the same family of semi metallic elements in which silicon is found. To take an example, compounds such as gallium arsenide or gallium nitride have interesting properties, such as the possibility of greatly increasing the clock speed with respect to the silicon16 (which would make it possible to resume the strategy of increasing speed as a mean to increase the performance of the chips), although it is currently a material that gives rise to a still expensive process, comparatively speaking.
It is expected, however, that as long as the different technological alternatives are developed, we will see how many of them coexist, since it is foreseeable that their differences in cost, production capacity, etc., will make each one of them to find applications and markets in which its implementation reaches the best cost-benefit ratio.
4.5. The Value of Technological Development in the Field of ElectronicsIt is commonly known that electronics is strongly disseminated in our society, its presence being increasingly evident in a multitude of applications and products. Throughout the last decades, anyone has been able to see how the number of electronic devices used in their daily life was increasing progressively, with perhaps mobile telephony being one of the greatest examples of how the most advanced electronic technology is present in our lives, and has changed them.
The electronics are in turn behind other advances that will reach their peak in the coming years, such as the technological revolution after concepts currently growing rapidly in industrial (industry 4.0, connected industry, digital industry, etc.) and consumers environments (internet of things, smart devices, etc.), all possible thanks to the humans being able to create very small chips, with high processing capacity, energy efficient and very combinable with other kind of technologies. In essence, and while all technologies within the KETS group are key to the future, it is undoubtedly electronics that has had and is having the most tangible effects on society as a whole.
4.6. Beyond ElectronicsWithin electronics, several branches and sub-disciplines can be differentiated, one of them being in many cases micro-nanoelectronics. As previously described, in this document we assume that the modern concept of electronics is already in a certain way "native" of the micro and nano scales, so
14 “Inside the High Stakesa Race to Make Quantum Computers Work”. Wired. March 2019. https://www.wired.com/story/inside-the-high-stakes-race-to-make-quantum-computers-work/
15 “Holey graphene as Holy Grail alternative to silicon chips”. Phys.Org. December 2018. https://phys.org/news/2018-12-holey-graphene-holy-grail-alternative.html
16 “Gallium Nitride is the Silicon of the Future”. The Verge. February 2019. https://www.theverge.com/2018/11/1/18051974/gallium-nitride-anker-material-silicon-semiconductor-energy
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it is useful to pay special attention to the branches of this discipline that are resulting in additional advances of great interest. In this context, there are several sub-branches that are worth to be highlighted because they show how electronics interact with other disciplines, giving rise to new fields of knowledge.
One of these fields is that of optoelectronic systems, those whose operation is directly related to light, in such a way that they are able to transform a light stimulus into a signal or series of electrical signals from which the system can perform a certain function. This definition could also be made in the opposite direction, contemplating a system that is capable of emitting light in a controlled manner based on a series of electrical stimuli. Optoelectronics is present in our lives in a very palpable way: the classic filament bulbs and modern LED lamps, any data display screen, lasers, light and presence sensing devices, solar panels,... Optoelectronics is not a new discipline, but rather classical, although it is true that it has increased its relevance at the present time, thanks to advances in sensor science allowing the development of efficient and more cost-effective components (emitters, detectors and photoconductors) and by allowing advances in capacity process (chips increasingly smaller and energy efficient), expanding its field of applications. In summary, the applications of optoelectronics are listed below17:
- Communications . Perhaps fiber optic is one of the most notable advances in this field, although there are numerous communications systems based on the detection, amplification, modulation, transmission and interpretation of light.
- Consumer electronics . Not only evident through the display screens included in many of the most common consumer products, but through the introduction of sensors and cameras that, for example, are able to unlock a phone through facial recognition, or recognize user gestures.
- Metrology and scanning . Very much in vogue thanks to the proliferation of all digital technologies for design and manufacturing, non-contact metrology and scanning technologies make use of light and images to characterize and/or measure physical elements.
- Illumination . From the incandescent lamp, and especially in recent decades, it is clear how the technology to produce light has been developed, evolving to the current and predominant LED lighting, and even considering the integration of electronic-lighting systems in flexible substrates.
- Solar cells . Photovoltaic systems have been present in society for decades in various applications, from low power applications (for example, calculators) to domestic applications (modern photovoltaic panels) and aerospace applications.
Another field of interest is embedded electronics. More than a branch of electronics we speak about computer and electronics systems, which designed for a specific purpose, include in its design all the electronic elements necessary to serve a defined function. Although its structure can be similar to that of traditional computers (processor, memory, storage, input and output interfaces, etc.), while the latter ones are general purpose hardwares, embedded systems tend to contain the
17 These applications are based on the ones depiceted by contents of the training course “Optoelectronics, Photonics and Sensors” by Santiago Silvestre, for the European Virtual Learning Platform for Electrical and Information Engineering”.https://upcommons.upc.edu/bitstream/handle/2117/103770/LM14_R_ES.pdf;jsessionid=ACC60D872C0A8763A88FCF91D24315D9?sequence=1
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elements justly required for the specific application sought. Thus, technologies as usual as that included in vending machines, dataphones for making payments, television decoders, currency exchange systems, etc., are examples of embedded systems. Nowadays, there are even very low-cost embedded systems (such as Arduino18 and Raspberry Pi19), which are thought of as general-purpose development boards for different hardware and software applications, since they include processing, visualization and communication technologies in very small spaces, serving as a basis for an accessible development of specific technology and applications.
In addition, thanks to the progressive miniaturization and increased efficiency of electronic systems, electronics is beginning to be physically embedded in many products that until now did not consider that they could be provided with certain functionalities, thanks to this integration. In this area, there are several points of attention:
- Smart textiles and wearables . Advances in miniaturization allow integrating chips in fabrics and clothes without prejudice to the user while their production on flexible substrates, opens the doors to the functionalization of fabrics.
- 3D printing . While the day when a 3D printer would be able to print a complete mechanical-electronic product only by itself may still be far away, the fusion of technologies and production systems can lead to interesting capabilities for the embedding of electronic printed parts20, ostensibly reducing and simplifying the complexity of the manufacturing sequences.
In both cases, as well as in all sub-areas that can be identified from the combination of electronics and other disciplines, micro and nanoelectromechanical systems (MEMS and NEMS) act as a basic pivot for technological development in any field.
In a basic way, MEMS are devices that combine electronic and mechanical components in a chip or embedded system, of very small size, used fundamentally for functions of sense and control of the environment. In this way, its fundamental function would be to perceive and/or measure a physical variable (pressure, temperature, light, flow, chemical elements and pathogens, etc.), from which the system generates an electrical signal, which can be processed and interpreted. The manufacture of MEMS is possible thanks to processes very similar to those used to manufacture electronic chips, in such a way that it is possible to manufacture not only silicon-based interruptors, but also structures, sensors and actuators, equipping these chips with added functionalities.
18“What is Arduino?”. https://www.arduino.cc/en/Guide/Introduction
19 https://www.raspberrypi.org/
20 “3D Printed Electronics Make this Drone Ready to Fly”. Allaboutcircuits.com. January 2017. https://www.allaboutcircuits.com/news/drone-3d-printed-with-embedded-electronics/
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Figure 3: Micro-chain drive fabricated in silicon at Sandia National Laboratory. Image21 under public domain by U.S. Department of Energy
It is for the above reasons that MEMS are a subject of special attention, since in different areas of application, such as the marine and maritime ones, this technology can lead to literally hundreds of applications, which in successive chapters we will try to address.
21 https://commons.wikimedia.org/wiki/File:U.S._Department_of_Energy_-_Science_-_463_017_001_(10190969504).jpg
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5. EU STRATEGY ON MICRO AND NANOELECTRONICSThe European Commission marked in 2013 the objective to double the economic value of the semiconductor component production in Europe by 2020-2025, which had its first results with the publication in 2014 of the document "A European Industrial Strategic Roadmap for Micro- and Nano -Electronic Components and Systems"22. The strategy depicted by this document is currently in force, and is integrated into the work programs of H2020 Framework and especially through the ECSEL Joint Technology Initiative23, from which guidance elements and tools for the development of Europe in digital and electronics matters were provided. In a concrete way, the roadmap established by the current strategy is illustrated below:
Table 2: Roadmap depicted by “A European Industrial Strategic Roadmap for Micro- and Nano -Electronic Components and Systems”
This strategy and its specific development through the H2020 framework and ECSEL JTI have been the basis of European support for technological development during the last five-year cycle and until 2020, when these strategies will evolve and consolidate around the next to come
22 “A European Industrial Strategic Roadmap for Micro- and Nano -Electronic Components and Systems”. European Comission. January 2014.
https://www.penta-eureka.eu/downloads/aeuropeanindustrialstrategicroadmapformicro-andnano-electroniccomponentsandsystems.pdf
23 ECSEL Joint Undertaking: Electronic Componentes and Systems for European Leadership. https://www.ecsel.eu/
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European scheme for the support for R&D, known as “Horizon Europe”24, currently on a proposal stage.
6. MEMS APPLICATIONS IN THE MARINE AND MARITIME FIELDS
6.1. Illustrative Examples: Gyroscopes and Accelerometers.As we have described in the previous sections, the progressively increasing capacities for the production of electronic systems to a smaller scale is also complemented by the capacity of these technologies for the manufacture and implementation of mechanical systems in similar scales. As an exemplification of the above, we would like to highlight two specific cases of elements that practically the entire population uses in their day-to-day life: gyroscopes and accelerometers.
- A gyroscope is composed of a symmetrical body with rotation capacity, which rotates continuously around an axis of symmetry. When it is subjected to a force that tends to change the orientation of this axis, it is capable of retaining its orientations, since it is the symmetrical body's own rotation that generates forces capable of opposing external forces, nullifying the external action.
- An accelerometer consists of two facing metal plates, one fixed and the other mobile, working as a condenser which capacity can vary, depending on the distance between said plates, and this distance depending of an external acceleration.
Figure 4. Gyroscope. Public Domain Image25 by LucasVB. / Accelerometer. Image26 by ALPR under Creative Commons Licence CC
BY-SA 4.0
Both inventions are present in most of people's lives, since these are devices implemented in almost all current mobile phones through MEMS components, being used for the detection of changes in position and orientation of the device, as well as gestures.
24https://ec.europa.eu/info/designing-next-research-and-innovation-framework-programme/what-shapes-next-framework-programme_en
25 https://commons.wikimedia.org/wiki/File:Gyroscope_operation.gif.
26 https://commons.wikimedia.org/wiki/File:Accelerometer_Spring.gif
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Figure 5: Printed circuit board of ETHOS, the ETH Orientation Sensor Image by Holger Harms. Image27 under Creative Commons Licence CC BY-SA 3.0
Devices like the above are the basis of many positioning and movement control systems, basic in any navigation applications; today and as it is widely known, thanks to production technologies inherited from the field of electronics, they are massively produced and integrated into a variety of products.
6.2. General Applications of MEMS in Marine and Maritime ApplicationsThe possibility of manufacturing mechanical elements at scales as small as micrometric has opened the doors to the development of multiple devices with different sensory capabilities, so that in general, we can differentiate at least the following types of sensors:
- Mechanical sensors: capable of measuring pressures, deformations, strain loads, torque, position, etc.
- Optical sensors: capable of detecting light emissions at the wavelengths required by the application.
- Temperature sensors: capable of measuring temperature and variations in it.- Acoustic sensors: able to perceive and measure sounds and vibrations of a medium.- Chemical sensors: capable of measuring PH, detecting contaminants or certain
substances/elements in the medium.- Biological sensors: capable of detecting microorganisms and/or pathogens.
MEMS serve as well as a technological basis for the "lab on a chip" concept, used to designate devices/platforms with sensory capacity, capable of providing specific and relevant information from the environment, in an agile, simple and affordable way.
Based on the above, it is possible to identify a series of general applications of MEMS in the marine and maritime fields:
27 https://commons.wikimedia.org/wiki/File:ETHOS_pcb.png
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- Navigation . Already sketched in the previous section, and in combination with many
subsequent applications, the development of MEMS sensors is the key not only for the implementation of location and positioning technologies, but also for the development of complete mobile platforms (potentially autonomous) for the collection and distribution of data at open water environments.
- Monitoring and prediction of weather . Traditional navigation and fisheries activities, as well as the proliferation of partially unassisted activities (associated with fields such as renewable energies or aquaculture) require complete sets of sensors capable of monitoring environmental variables, leading to short and medium term weather prediction systems, capable of favouring increases in productivity.
- Water monitoring . The monitoring of water properties and composition is a tool of high value at the time of establishing if for example a given water quality is suitable for maximizing the production of an aquaculture activity, if pathogenic agents are present, if there are unwanted variations of acidity, etc.
- Monitoring of marine structures . Any activity carried out continuously in marine environments is inherently subject to external aggressions, capable of deteriorating the most solid structures in the absence of adequate controls and maintenance. In this sense, there are sensors developed thanks to MEMS technology, capable of measuring variations in the stresses to which the structures are subjected, this being an important element when maintaining them and preventing accidents.
- Marine biology and chemistry studies . Sensor technology for the detection of analytes is also being developed at microelectromechanical levels, so that in combination with microfluidics, it is feasible to develop devices of very small size, with the capacity to act as real laboratories/labs on a chip.
- Marine exploration and prospection . The marine exploration is a wide discipline, ranging from the survey of marine beds looking for the early detection of earthquakes in the sea, until the detection of marine deposits. At the same time is obvious how the implementation of these technologies for autonomous or semi-autonomous operations can be a tool of high relevance when exploiting underwater resources.
6.3. Outstanding MEMs Applications in Marine and Maritime Fields.
6.3.1. Navigation Systems.In a complementary way to the navigation systems based on GPS technology, the inertial navigation systems (Inertial Measurement Unit, IMU) are capable of establishing the position of an object without external references. Basically, an inertial navigation system emerges as a combination of various sensors, mainly accelerometers and gyroscopes, which combined with a computing system, are able to obtain the position and speed of an object without the need for such external reference. In this way, these systems are able to detect displacements in the geographical
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position, inclination and rolling, changes in the direction and speed, as well as in the orientation, without the interference to which systems such as GPS can be subjected. In the maritime field, these are especially useful systems for devices that require a continuous and precise positioning, in a paradigm in which a proliferation of autonomous navigation systems is expected.
These systems have already been developed at the MEMS scale, with chips already available in the market that combine accelerometers, gyroscopes and motion processing units in very small packages, capable of serving for the development of the described applications. An example is the device MPU605028 of INVESENSE, shown in the following image:
Figure 6: Invensense MPU6050 is an integrated gyroscope and accelerometer with 16-bit readings. It contains two dies which are soldered/welded face-to-face in multiple places. Image29 by ZeptoBars under Creative Commons Licence CC BY 3.0.
The use of this class of components is frequent in the state of art, as a basis for the planning and development of IMUs, in different marine applications; in a concrete way, the specifically mentioned component has been the basis of the following developments and investigations in the recent past:
- Implementation of Digital IMU for increasing the Accuracy of Hydrographic Survey30.- IMU for Vessel and Offshore Piping Survey31.- Vibration monitoring system of ships using wireless sensor networks32.- Development a Self-rescue System for Autonomous Underwater Vehicle Using Micro-
Inertial Sensing Module33.- Mobile Augmented Reality System for Marine Navigation34.- Self-balance system for naval operation vehicles35.
28 https://www.invensense.com/products/motion-tracking/6-axis/mpu-6050/
29 https://commons.wikimedia.org/wiki/File:Mpu6050-HD.jpg
30https://www.sciencedirect.com/science/article/pii/S1877705817333131/pdf?md5=38f2865122c9300a27d68a4dc55684c2&pid=1-s2.0- S1877705817333131-main.pdf
31 http://www.hrpub.org/download/20150201/UJIBM2-11603263.pdf
32 https://www.researchgate.net/publication/271545330_Vibration_monitoring_system_of_ships_using_wireless_sensor_networks
33 https://pdfs.semanticscholar.org/6315/b96cc17ffb6acb92c9fb43b703f82d020207.pdf
34 https://www.theses.fr/2015LORIS365.pdf
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- Structural Health Monitoring of Offshore Structures Using Wireless Sensor Networking
under Operational and Environmental Variability36.- MEMS inertial sensors for load monitoring of wind turbine blades37.
The above is proof that this technology is frankly fruitful when it comes to developing technology for the marine field, since its accessibility and low cost facilitates the realization of developments adapted to a large part of marine applications that demand precise control of the positioning, location, and the rest of the variables associated with the movement.
6.3.2. Autonomous exploration and Exploitation of Marine Resources.Beyond being a traditional source for fishing and fossil fuels resources, the marine environment is currently revealed as a source of many other activities based on seas and oceans: marine renewable energies, deep-sea mining, offshore aquaculture, algae farming, etc. Good part of the future development of these applications is based on two pillars:
- Obtaining information minimizing the cost of operation . Due to its very nature, all the activities carried out in the marine environment imply significant operating costs, either linked to preparatory activities for the exploitation of resources (examples: mapping and survey of sea beds in order to characterize marine resources, mapping of tides and waves for the production of energy, wind maps, etc.), or the exploitation itself (adjustments and maintenance based on the monitoring of environmental variables, in the search for the parameters of operation that maximize production).
- Autonomy of operation . Much of the productive activities in seas and oceans take place at great distances from the coasts, where any work of intervention and direct monitoring, maintenance, etc., imply significant operating costs. In this way, a good part of the profitability of these operations will depend on the ability to develop technology with considerable autonomy, capable of being monitored and operated remotely, in complex networks capable of achieving at all times the best adjustment between the components of said network.
It is then obvious that a good part of the success of the aforementioned activities depends largely on the concept of automation, in which the MEMS are critical for obvious reasons:
- MEMS have the capacity to incorporate sensors with which to capture relevant information for the monitoring and adaptation of activities at sea: temperature, pressure, winds, currents, position, waves...
35 https://iopscience.iop.org/article/10.1088/1757-899X/494/1/012108/pdf
36 https://waset.org/publications/10003301/structural-health-monitoring-of-offshore-structures-using-wireless-sensor-networking-under-operational-and-environmental-variability
37https://www.researchgate.net/publication/273447182_MEMS_inertial_sensors_for_load_monitoring_of_wind_turbine_blades
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- As the manufacturing systems of the MEMs "heirs" the ones implemented for
microelectronic applications, their manufacturing costs tend to be reduced, which gives rise to the proliferation of their integration in specific embedded electronic systems: navigation, detection, monitoring, etc.
- In a basic way, MEMS enable the development of control systems for offshore applications, which together with wireless communication capabilities allow the configuration of systems with autonomous control and remote control capabilities, while being part of global networks through which deep optimizations can be performed.
- MEMS are in turn the basis for the development of navigation and autonomous vehicles, which, increasingly compact and capable, are authentic platforms for obtaining information at sea.
Figure 7: Autonomous Surface Vehicle. Public domain image by the Office of Naval Research (USA) / Saildrone38. Public domain Image by U.S. National Oceanic and Atmospheric Administration / Iver Autonomous Underwater Vehicle39. Public Domain Image by the
National Oceanic and Atmospheric Administration (USA)
6.3.3. Monitoring and prediction of weather.The monitoring and prediction of weather at sea is a labour of unquestionable value for the realization of any offshore activity, in such a way that weather is a critical variable for various operations and sectors. Thus, the weather can be a variable for the safety of an operation (any involving maritime or low-altitude aerial navigation) or even for its performance (for example, maintenance operations of offshore wind structures is more efficient when done in periods of weak winds). One of the clearest examples of the power of the sensors in the most cutting-edge applications within the marine environment is the implementation of MEMS sensors in buoys, as it is the case of the buoy illustrated in the following image:
38 https://www.saildrone.com/
39 https://ocean-server.com/iver3/
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Figure 8: CB-1250 Nexsens Data Buoy. deployed in Lake Erie at Presque Isle to transmit weather and water quality data back to shore. Image40 by Fondriest Environmental41, published under Creative Commons CC BY-NC 2.0 licence.
This buoy, from the company NexSens, is a platform on which diverse sensors can be implemented, such as the hardware SVS-60342 from Seaviewsystems, a small electronic board provided with inertial sensors for the monitoring of the heading, wave height, wave period and wave direction. It is obvious how systems of this kind can be of great importance for developing applications in the field of marine renewable energies, where the characterization of tides and waves is of vital importance. Examples focused on these applications are illustrated in articles such as "Sensor Buoy System for Monitoring Renewable Marine Energy Resources"43, where the designed buoys are equipped with wave sensors, current meters, and a weather stations.
These systems are also capable of operating in combination with other buoys and with centralized information management systems, forming networks for obtaining complete information from the environment; projects like LifeDEmowave44 are developing these kind of applications, focused on the design and prototyping of complex networks for the management of environmental information.
6.3.4. Structural Health Monitoring.The investments necessary to erect structures in the sea are really considerable, so they are subject to important monitoring and maitenance costs, in order to ensure maximum durability and operational performance. This brings about the discipline of structural health monitoring, which nowadays implements sensor networks capable of collecting and processing data, in unified systems that allow monitoring complete sets of assets during their life cycle. Thus, there are sensors capable of measuring variables such as inclination, displacement, scour, the appearance of fractures, noise, vibration or leaks. The development of microelectronics has allowed as in other fields, the improvement, simplification and reduction of the cost thereof, also increasing operational capabilities. Thus, the total integration of the sensorization technologies with those of wireless
40 https://www.flickr.com/photos/fondriestenvironmental/14516694421
41 https://www.fondriest.com/
42 https://www.seaviewsystems.com/products/data-buoy-instruments/svs-603-inertial-wave-sensor/
43 “Sensor Buoy System for Monitoring Renewable Marine Energy Resources”. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5948478/
44 http://www.life-demowave.eu/es/
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communication has led these systems to a great advance in a reduced time, allowing the optimization of monitoring and maintenance tasks.
Based on the wide variety of sensors capable of capturing information for the monitoring of structural health, it is perhaps appropriate to establish an example from which to show the potential of MEMs in this regard, with the case of extensiometric micro-gauges as a basis. Basically, an extensiometric gauge is a deformation sensor, consisting of an electrical circuit that varies its resistance as a function of the forces to which the gauge is subjected, in such a way that it is possible to establish correlations and use them to evaluate the effort suffered from a structure.
Figure 9: Strain gauge working concept. Image45 by Izantuxc under Wikkimedia Commons CC0 1.0.
In this sense, the use of MEMS technology allows the development of strain gauges not only of smaller size, but also with considerably more complex structures, which gives the MEMS strein gauges greater sensitivity and resolution, as well as greater resistance to impacts (thanks to its smaller size). The article "Design and Simulation of a Microelectromechanical Double-Ended Tuning Fork Strain Gauge"46 is very illustrative of the capabilities that microelectronics can bring to this type of devices.
There are of course another examples in the state of the art, as MEMS based inertial sensors are being used for the monitoring of off-shore structures, such as in the case of wind turbine blades, in which there are commercial sensors47 capable of carrying out vibration analyzes.
6.3.5. Biologic and Marine Pollutants Studies.The role of sensors in the monitoring of biological and chemical agents is undoubtedly relevant, with several applications that can benefit from a detection capacity of different microorganisms and pathogens: detection of viruses and infections, acidity of waters, detection of chemicals harmful to life, corrosion and biofouling control, etc. In this area, most of the MEMs advances in recent years have been related to the development of systems resulting from the fusion between electronics and microfluidics.
Microfluidics is a discipline that designs and develops systems and capacities to process really small amounts of fluid, through the fabrication of structures equipped with microchannels. In these
45 https://commons.wikimedia.org/wiki/File:StrainGaugeVisualization.svg
46 “Design and Simulation of a Microelectromechanical Double-Ended Tuning Fork Strain Gauge”. A. Bardakas, H. Zhang, W.D. Leon-Salas. School of Engineering Technology, Purdue University, West Lafayette, IN, USA. 2017. https://www.comsol.com/paper/download/437602/zhang_paper.pdf
47 As for exaample the vibration sensor VS1000 from Safran Colibrys. https://www.colibrys.com/wind-turbines/
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conditions, the behavior of the fluids is different from the behavior in larger volumes, which translates into important differences in factors such as surface tension, speed and flow distribution. In these conditions and with such small channels, the processes that allow the detection of substances takes place very quickly and in a very localized way, making it possible for these devices to perform functions similar to traditional laboratory equipment. Thus, the combination of microfluidics and microelectronics gives rise to the "lab on a chip" concept. In general, devices of this type derive from a previous one on a macroscopic scale, in which the functionality has already been correctly validated and put to the test, and whose miniaturization offers a large number of advantages, such as a lower consumption of chemical reagents, high resolution and sensitivity, short product synthesis times, greater control over chemical reactions through more efficient control of concentrations, etc.
There are some remarkable experiences in the field of the development of lab on a chips for different applications within the marine field, altough in this document we wanted to highlight the following ones, for belonging to important European projects of recent development:
- Sea on a Chip Project. This project48 led to the development of a detection platform, consisting of a network of chips equipped with sensors, located on the perimeter of a fish farm. This network of sensors is located on small buoys, containing each chip (about 10 cm in total size) its own energy source, the chemical reagents necessary for the analysis and the electronic components to receive and transmit the data. Each chip is equipped with biosensors for the analysis of 7 compounds, from natural toxins to emerging contaminants, such as polybrominated compounds or antibiotics.
- Braavoo Project. This project49 developed a floating laboratory, installed in a small autonomous catamaran controlled remotely, whose analytical results are sent to a central data collection. The measuring station integrates three different types of sensors: optical technology immunosensors, sensors for the detection of compounds such as mercury and algae sensors.
7. LOOKING TO PATENTS TO MEASURE MEMS RELEVANCE
48 http://www.sea-on-a-chip.eu/V1/SOC50V4_Main.php
49 http://www.braavoo.org
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As a brief introduction to the methodology used to elaborate this section, the authors have made use of the Derwent Innovation50 tool as a main patent database, which has allowed to carry out a series of preliminary studies to give rise to the data shown. Aiming at results and analyses done to be reproducible by any reader, the use of the previous tool has been complemented by the use of the free search tool available at Lens.org51, which allows free searches and a simple analysis and filtering of patent information.
As it was seen in previous sections of this document, MEMS are the logical evolution of micro and nanoelectronic production systems towards the manufacture of devices that, by integrating mechanisms at this scale, give rise to chips with sensory capabilities. This has led to the proliferation of technology at many levels, giving rise to applications in many sectors and markets. It is for the foregoing that the applications of MEMS in the marine field, although relevant as we have seen, are in practice "a drop of water in the sea" of the potential applications of the same. MEMS technology itself does not pose any kind of limitations when it comes to application development, as long as there is a sensorized mechanism that can be manufactured using existing technologies.
Patents are always a great indicator of the relevance of a technology, since especially through the review of data over the years it is possible to assess the relevance of such technology as an active field of research, development and commercial exploitation. In the case of this document, a search has been carried out that corresponds to the terms "MEMS sensor"/"MEMS Device", in order to avoid meanings of the term "MEMS" that may not be linked to electronics. We can see below the most significant results:
- Temporal evolution of the number of patents . The following data shows how the production of patents in the field of MEMS sensors/devices has steadily increased over the last decade, reaching very high annual production numbers, which indicates that the relative importance of MEMS is increasing, while at the same time indicating that the pace of Innovation in this field is far from over.
50 https://www.derwentinnovation.com tool (proprietary software) created by Clarivate Analytcis, that gives access to a curated database of patents, allowing complete searches and processing of data, used by professionals in the field of patents.
51 https://www.lens.org/
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YearPublished
PatentsAnual
Growth2010 3.562 9,47%2011 3.386 -4,94%2012 3.568 5,38%2013 3.960 10,99%2014 4.644 17,27%2015 4.831 4,03%2016 4.938 2,21%2017 5.437 10,11%2018 5.392 -0,83%
0
1.000
2.000
3.000
4.000
5.000
6.000
2010 2011 2012 2013 2014 2015 2016 2017 2018
Published Patents "MEMS Sensor/Device" 2010 -2018
Figure 10: Temporal evolution of the number of published patents containing “MEMS Sensor” or “MEMS Device” in text fields for the period 2010-2018. Data Source: Lens.org. Tables and charts: own creation
- Prominent patent families . The graph below shows as prominent patent families in the last 10 years the following ones:
IPC Code Description Published Patents
B81C1/00Manufacture or treatment of devices or systems in or on a substrate
3.790
B81B3/00
Devices comprising flexible or deformable elements, e.g. comprising. elastic tongues or membranes.
2.319
B81B7/00 Microstructural systems 2.240
B81B7/02
Microstructural systems containing distinct electrical or optical devices of particular relevance for their function,
1.264
A61B5/00 Measuring for diagnostic purposes 1.238
H01L29/84
Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having at least one potential-jump barrier or surface barrier; Capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g.
1.092
G02B26/08
Optical devices or arrangements using movable or deformable optical elements for controlling the intensity, colour, phase, polarisation or direction of light for controlling the direction of light
1.034
G02B26/00
Optical devices or arrangements using movable or deformable optical elements for controlling the intensity, colour, phase, polarisation or direction of light
968
H01L21/00
Processes or apparatus specially adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
796
G01P15/125Measuring acceleration; Measuring deceleration; Measuring shock by capacitive pick-up
779
0 500 1.000 1.500 2.000 2.500 3.000 3.500 4.000
G01P15/125
H01L21/00
G02B26/00
G02B26/08
H01L29/84
A61B5/00
B81B7/02
B81B7/00
B81B3/00
B81C1/00
Published Patents "MEMS Sensor/Device" 2010 - 2018 per subcodes
Figure 11: Patent main sub-codes count of published patents containing “MEMS Sensor” or “MEMS Device” in text fields for the period 2010-2018. Data Source: Lens.org. Tables and charts: own creation
- Most active patenting countries . The distribution shown by the following chart leaves no room for doubt: USA accumulates practically a 75% of the industrial protection activity in
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the field of MEMS sensors/devices throughout this decade. There is a considerable count of patents with worldwide scope, which is usually indicative of patents with a high degree of solidity and a very broad commercial perspective. Europe and China are next in relevance, although far away from the United States.
CountryPublished Patents
%
USA 27.847 70%
World Patents 5.501 14%
Europe 2.098 5%
China 1.683 4%
Other Countries
2.589 7%
70%
14%
5%4%
7%
Published Patents "MEMS Sensor/Device" 2010 - 2018 by country
USA
World Patents
Europe
China
Other Countries
Figure 12: Most active patenting countries of published patents containing “MEMS Sensor” or “MEMS Device” in text fields for the period 2010-2018. Data Source: Lens.org. Tables and charts: own creation
- Main applicants . A simple analysis of the main patent applicants is consistent with the data we have just shown, and is that some of the most important names in the electronics sector are at the forefront of industrial protection activity: Qualcomm, Intel, Invensense, etc.
OrganizationPublished
Patents%
Qualcomm Mems Technologies Inc 1661 4,2%Intel Corp 922 2,3%Invensense Inc 707 1,8%Freescale Semiconductor Inc 547 1,4%Bosch Gmbh Robert 538 1,4%Analog Devices Inc 532 1,3%Honeywell Int Inc 503 1,3%Infineon Technologies Ag 479 1,2%Taiwan Semiconductor Mfg Co Ltd 479 1,2%Taiwan Semiconductor Mfg 463 1,2% 0 1000 2000
Taiwan Semiconductor Mfg
Infineon Technologies Ag
Taiwan Semiconductor Mfg Co Ltd
Honeywell Int Inc
Analog Devices Inc
Bosch Gmbh Robert
Freescale Semiconductor Inc
Invensense Inc
Intel Corp
Qualcomm Mems Technologies Inc
No. Patents "MEMS Sensor/Device" 2010 - 2018 per applicant
Figure 13: Most active patenting organizations of published patents containing “MEMS Sensor” or “MEMS Device” in text fields for the period 2010-2018. Data Source: Lens.org. Tables and charts: own creation
Far from constituting an in-depth analysis, the data shown are nevertheless good indications that:
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- The increase in industrial protection activity in the present decade in the field of MEMS can
be derived from an increase in the pace of innovation and technological change in the sector.
- United States is without a doubt the most relevant patenting “actor”, as this country accumulates alone nearly ¾ of the total patent production. In comparison, Europe and China (next in the classification) are secondary regions.
- Main semiconductor technologies providers (mainly from the United States) are carrying out most part of the protection activity related to MEMS.
In addition to the analysis carried out, a series of references to some representative patents on MEMS marine applications have been included as an annex to this document.
8. CONCLUSIONSThe advances in the capacity of the human being to give place to progressively more advanced and small electronic devices has been a key element for development at all technology levels. The production processes that have made possible our current micro and nanoelectronic capabilities are also the basis for the chips not only containing electronic components, but also integrating mechanisms for sensing applications, resulting in a fusion between electronics and mechanics. From this combination arise a host of applications, from which activities in the marine field can benefit. Thus, as we wanted to convey in this document:
- The possibility of implementing MEMS sensors in small electronic devices is the gateway for the development of embedded electronic systems for specific applications, as navigation, detection, monitoring, control, etc., or a combination of all the above.
- On the other hand, the nature of MEMS devices as coming from manufacturing processes oriented to mass production, places them as tools of low or moderate cost for the development of the previous applications, demanding lower levels of investment.
- The specific electronic systems that can be developed thanks to the existence of MEMs are key to create business models and production schemes oriented towards remote or autonomous management, a key aspect for the profitability of many of the possible operations in the marine field.
- MEMS technology is not a possibility for the future, it is technology already available. The leading producers of electronics worldwide have spent years doing important research, production and commercial activity, so it is a technology with a high degree of maturity for several applications.
On the other hand, both the electronics in general and the MEMS in particular will enter in the coming years at a “turning point”. The improvement of the current technology of silicon semiconductors and the possible progression towards new semiconductors of greater capacity or other alternatives will increase more if possible the current capacities.
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9. ANNEX: Representative MEMS Marine Applications PatentsSome representative patents on MEMS Marine Applications are shown below (free patent databases like Espacenet52 can be used to consult them in more detail):
- Xin Wangshi, Fu Lishan, Chen Daidai, Li Peizheng, Huang Xiange, Lian Xuehai, Wu Majun. “Mems-based Compensation Method For Marine Solid-state Navigation Radar Target Detection”. CN 108761420 A.
- Xue Chenyang, Zhang Guojun, He Changde, Wang Renxin. “All-sea-depth Turbulent Mixing Matrix Profile Observation System Based On Mems Technology”. CN 106218838 A.
- Wei Yanhui, Gao Yanbin, Zhang Haoyuan, Guo Rui. “Underwater Robot Dual-redundancy Gesture Detecting System”. CN 106500721 A.
- Zhao Shulun, Yu Qingbo, Men Jizhuo. “Sotm Pseudo Course Sea Ship Dynamic Satellite Searching Method Based On Kalman Filtering”. CN 105116430 A.
- Hu Qiao, Li Yiqing, Wang Zhaohui, Liu Yu. “Underwater Bionic Lateral Line Water Pressure And Water Flow Field Information Detection Method Based On Neural Network”. CN 108304810 A.
- Okulov Paul D. “Micro Electro-mechanical Strain Displacement Sensor And Usage Monitoring System”.EP 3230199 A1.
- Univ Leland Stanford Junior. “Oriented Wireless Structural Health And Seismic Monitoring”. US 2014/0316708 A1.
- Salzer Corey Alan, Rajasekharan Vishnu Vardhanan, Huenig Isabel Nicola, Froemel Rainer. “Alkalinity Analysis Using A Lab-on-a-chip”. EP 2596347 B1.
- Wang Yafang. “Farmed Fish Intake Information Detector With Mems Acceleration Sensors”. CN 104969897 A.
- Romang Derek. “Bite Indicators”. GB 2499420 A.- Han Jun, Huang Ren Ai, Tong Jianfeng, Ying Yixing. “Long-line Fishing Monitoring
System”. CN 104504873 A.- Li Chen. “All-weather Intelligent Monitoring System And Wristwatch Type Intelligent Monitor
Controller”. CN 105193407 A.- Council Scient Ind Res. “An Aerodynamic Lift Generation Device Using Unsteady Vortices”.
IN 300DE2012 A.- Zaki Ahmed S, Straw Timothy B, Obara Michael J, Child Peter A, Us Navy. “High Accuracy
Heading Sensor For An Underwater Towed Array”. US 8768647 B1.- Univ South Florida. “Reinforced Piezoresistive Pressure Sensor”. US 7856885 B1.- Yang Hua, Bai Xingwang, Song Dalei, Wang Xiangdong. ”Mems-based Oceanic
Turbulence Sensor”. CN 106289624 A.- Dong Liu, Yishan Gu. “Novel Ship Hydraulic System Power Sensor”. CN 201896800 U.
52 https://worldwide.espacenet.com/
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