M.tech projects 2012 13

M.Tech. Project Session (2012-13) : Topic #1

Project Title: “Modelling of MOSFET Embedded Sensor for MEMS applications.”

Supervisor: B.S. Panwar.

Objective: Modelling and simulation of strain-induced mobility of a MOSFET as function of applied stress.

Summary:

Sensing mechanism is one of the most important issues in the field of sensors. Several transduction mechanisms are available in literature which includes optical detection, capacitive, piezoelectric and piezoresistive sensing. Recently, embedded transistor technique [1] is reported in which there is a change in the carrier mobility and drain current of a metal oxide semiconductor field effect transistor (MOSFET) when stress is applied. A novel MOSFET pressure sensor was proposed based on the MOSFET stress sensitive phenomenon, in which the source-drain current changes with the stress in channel region. The use of piezoresistance model to describe the stress induced carrier mobility change has also been reported [2-4]. Two MOSFET’s and two piezoresistors were employed to form a Wheatstone bridge served as sensitive unit in the novel sensor [5]. The use of MOSFETs for strain sensing will have the following advantages of high sensitivity, low cost, easy integration of low power CMOS electronics with the MEMS sensors and less complicated signal conditioning circuitry.

References:

[1] G. Shekhawat, S.H. Tark, and V.P. Dravid, “MOSFET embedded microcantilevers for measuring deflection in biomolecular sensors,” Science, vol. 311, pp. 1592-95, 2006. [2] S. Suthram, J.C. Ziegert, T. Nishida, and S.E. Thompson, “Piezoresistance coefficients of (100) silicon nMOSFETs measured at low and high (~1.5 GPa) channel stress,” IEEE Electron Device Letters, vol. 28, no. 1, 2007. [3] Y.L. Tsang, A.G. O’Neill, B.J. Gallacher, and S.H. Olsen, “Using piezoresistance model with C-R conversion for modelling of strain-induced mobility,” IEEE Electron Device Letters, vol. 29, no. 9, 2008 [4] J.S. Wang, W.P. Chen, C. Shih, C. Lein, P. Su, Y. Sheu, D.Y. Chao, and K. Goto, “Mobility modelling and its extraction technique for manufacturing strained-Si MOSFETs,” IEEE Electron Device Letters, vol. 28, no. 11, 2007. [5] Z.H. Zhang, Y.H. Zhang, L.Liu, T.L. Ren, “A Novel MEMS Pressure Sensor with MOSFET on Chip,” IEEE SENSORS Conference, 2008.

M.Tech. Project Session (2012-13): Topic #2

Project Title: “Modeling of Piezoelectric (PZT) materials for actuation of various MEMS structures.”

Supervisor: B. S. Panwar.

Objective:

(1) Modeling and simulation of PZT actuated catilevers and diaphragms for MEMS based Resonators for force and mass sensing applications.

(2) Integration of these PZT MEMS structures with CMOS based differential amplifier.

Short description:

Microcantilevers, bridges and diaphragms are the most simplified and common MEMS structures in the field of micromachined transducers. These MEMS structures are relatively simple and inexpensive to fabricate and analytical solutions of their displacement profiles and stress distributions under load are well developed. These structures are commonly used as force and displacement sensors as well as mass sensors when excited in resonance. When used in dynamic or resonance mode, these structures are mechanically deflected by different actuation techniques, piezoelectric being most commonly used. Numerous microcantilever devices have been implemented for ultra low mass sensing for biological and chemical applications [1,2]. The motion of a cantilever beam can be sensitively monitored by means of a variety of techniques, such as variations in piezoresistivity, piezoelectricity, capacitive method, optical beam deflection and embedded transistor semiconductivity. This work will also emphasize on the embedded MOSFET sensing technique. In order to reduce the number of off-chip components required to operate a sensing system, more and more microelectronic building blocks are integrated together with the microsensor on the same chip [3,4]. In this project work we propose the integration of PZT actuated MEMS structures with a CMOS based differential amplifer which will amplify only the difference signal of the sensing and the reference sensors, and also minimizes systematic noise and environmental perturbations. Use of embedded MOSFET sensing technique will further ease the integration of low power CMOS electronics and MEMS structure.

References:

[1] Y. T. Yang, C. Callegari, X. L. Feng, K. L. Ekinci, and M. L. Roukes, “Zeptogram-Scale Nanomechanical Mass Sensing,” Nano Lett., Vol. 6, No. 4, 2006. [2] B. Ilic, and H. G. Craighead, “Attogram detection using nanoelectromechanical oscillators,” J. Applied Physics Vol. 95, No. 7, 2004. [3] G.K. Fedder, R.T. Howe, T.J.K. Liu, and E.P. Quevy, “Technologies for Cofabricating MEMS and Electronics,” Proceedings of the IEEE, Vol. 96, No. 2, 2008. [4] O. Brand, “Microsensor Integration Into Systems-on-Chip,” Proceedings of the IEEE, Vol. 94, No. 6, June 2006.


Project Title: “Design Optimization of Piezoelectric Energy Harvester”


Objective: Virtualization of Piezoelectric Energy Harvester Design Using COMSOL, MATLAB interface with Power Management Circuit

Project Summary In the present work a comprehensive literature survey is to be completed and the issues that need to be addressed to bring the MEMS based energy harvesting systems a viable system for charging of wireless sensors nodes and cellular phones is to be examined. This project will concentrate on the optimization of PZT micro-cantilever geometry to convert the mechanical vibrations to electrical signal using Data Acquisition Toolbox for connecting MATLAB to data acquisition hardware. This methodology requires interface of PZT micro-cantilever design software with MATLAB which can be connected to the power management circuit using the appropriate sampling rate data acquisition card. This will facilitate conversion of simulated mechanical vibrations to an electrical signal, which can be used to drive the power management circuit. There is large number of options for ac/dc conversion architecture. The best architecture need to be identified analyzed and interfaced with the virtual design philosophy using COMSOL and DATA acquisition Tool Box of MATLAB. In this process a virtual design platform is to be formed which interfaces the COMSOL design tools with the power management circuit using a data acquisition card. A typical block diagram of such a configuration is shown below:

The definition and scope of work can be described as below: 1. Establishing the interface between the cantilever design tools COMSOL with

MATLAB using the Data Acquisition Tool box. 2. Identification and selection of proper sampling rate data acquisition card and

establishing its functionality with the personal computer or laptop. 3. Interface of the ac signal obtained from DAQ interfaced with Personal Computer and

analyzing the complete structure using the Simulink Design Tools. 4. Optimizing the geometry of the piezoelectric energy harvester to get the maxm. power

delivered to the battery for charging.


Project Title: “Design and Implementation of Wireless Body Area Network ”


Objective: Developing a patient monitoring system using body area network.

Project Summary Design and implementation of a Wireless Body Area Network for health care applications: Patient monitoring in a hospital environment is becoming more and more complex with multiple parameters (ECG, EEG, temperature, pressure, etc) to be measured and the need to network the data gathered from many patients for observation at a central monitoring station. The objective of present project is to design a wireless communication protocol for the multiplexing of data gathered from multiple patients and to use a fiber optic link to collect the multiplexed data streams and transmit them to the monitoring station for analysis and interpretation The work will involve selection and acquisition of biomedical sensors, development of hardware for data processing and RF interface for wireless communications. Different multiplexing approaches like TDMA, FDMA, CDMA, SDMA will be investigated and the best one implemented. The multiplexed data streams will be collected together and fed to a fiber optic communication link for data transmission to the sink node. MATLAB will be used with an appropriate DAQ for data acquisition, display, monitoring and analysis. This is hardware based project and efforts will be made to develop a prototype of the proposed system and test it in a realistic environment.


Project Title: “SAW based wireless sensor Netwrok ”


Objective: Developing wirelessly interrogatable sensor network.

Project Summary Development of a passive, wirelessly interrogable sensor network based on SAW devices: In harsh industrial environments like high temperature , pressure, radiation, moving machine parts, etc, it is impossible to use conventional semiconductor based sensors with wired connections. Sensors need to be embedded in structures like bridges and implanted in patients for health care applications which requires battery less operation (for a long lifetime). Surface Acoustic Wave technology provides us with a wide variety of passive, wirelessly interrogable sensors, based on wide band delay lines and narrow band resonators, which are able to operate satisfactorily in extremely harsh environments. The objective of the present project will be to design and fabricate SAW sensors for detection of temperature, pressure, gases, etc using delay lines and resonators. The reader electronics will be developed to wirelessly interrogate the SAW sensors and extract information from them. To increase the number of sensors in the network, multiple access schemes like TDMA, FDMA, CDMA, SDMA will be studied and developed. At the end of the project, we should have some SAW based sensors and electronics for interrogating them. It should be possible to demonstrate the interrogation of multiple SAW sensors using an appropriate multiple access scheme.


Project Title: “Evolving New Techniques of Recording Brain Waves and Telepathy a Future Mode of Communication”

Supervisor: B. S. Panwar, and Dr. Puneet Agarwal- Senior Neurologist Max Hospital

Objective: Analysis of recorded brain waves for predicting mental disorder and proposing brain waves a Future Mode of Communication”

Project Summary: To record the brain waves with newer techniques in more comprehensive and sensitive manner so that we can detect different neurological and even mental disorders (psychiatric) in very early stage which will help in treatment as well as in prevention. The project can be outlined as below:

1. A comprehensive survey on the tools and techniques of recording brain waves. 2. Analysis using standard signal processing tools for finding the deviations in the

recorded brain waves Delta, Theta, Alpha, Beta and Gamma for a normal and a person having mental disorder.

3. Proposing new techniques of recording brain waves to record the electrode potential in graded manner, recording ultrasounds accounting for movement of different parts of the brain.

4. High speed digital recording of EEG signals for improved interpretation and diagnostics.

5. Exploring telepathy as the future mode of communications.

Documents

M.tech projects 2012 13