Need for Hand-Crank Powered Otoscope in Rural AreasAnshuman Gupta

Abstract

The need for affordable medical devices is paramount for improved health care in rural areas around the globe. Specifically for child and maternal health, adequate access to health care professionals and equipment is essential for maintaining and even raising the quality of care. Otoscopes are an integral part of a standard medical examination. These devices are for examining the ear canal of patients. Children are especially susceptible to ear infections given the anatomy of the Eustachian tubes and otoscopes are useful for detection and subsequent treatment. The key problem in rural areas for otoscope dissemination is the access to power sources. Whether powered by battery of wall-mounted socket, powering the LED is necessary for functionality. Using a hand-crank power generator can remove this problem completely. A manual power generator will give a renewable and unlimited power source for the otoscope. The method for alleviating this need is to have a hand-powered otoscope using a magnet to power the LED. This method was used and, though it was validated, found to be inadequate for the purposes of a useable medical device.

Product Need

Worldwide, there is a crucial need for innovative, inexpensive medical technologies in rural areas. Globally, healthcare needs range from reduced cardiovascular health and vitamin deficiencies. According to the World Health Organization, the leading causes of death all affect cardiovascular health. In addition, child and maternal healthcare is clearly linked to malnutrition (WHO Global Health Risks Report). Figure 1 indicates the breakdown of the leading death risks globally. As can be seen, each risk has also been split into risks for high, medium and low income countries. According to a paper written in 2009, infection rates in children under the age of 5 have a direct correlation with malnutrition (Nohvnek 2009). Nohvnek notes that fifty percent of the infection cases shown in Figure 2 were a direct result of malnutrition.

Figure 1 (WHO Global Health Risks Report)

Another paper discusses the dramatic need for access to medical professionals among rural tribes and villages in order to improve the general healthcare of people in rural communities (Bala 2009). Bala discusses the major problem of manpower in getting healthcare to tribal communities. In India, there are only 4% of the doctors are available to the rural communities, which account for 8% of the population.

The lack of access to medical professionals is a problem compounded by the high cost of medical equipment. A 2004 paper on the efficacy of portable ultrasound devices in hospitals demonstrates the improvement in healthcare due to access to better technology. Figure 3 below shows the percentage of cases in which medical treatment was changed as a direct result of the use of the ultrasound device (Gorcsan 2004). The access to the ultrasound device gave doctors a new and improved diagnosis tool and directly affected treatment for the patients in the study.

Figure 3 (Gorcsan 2004)

Figure 2 (Nohvnek 2009)

Ear infections occur most often in children ages 2-3 years but can also be common for children as old as 5 or 6. The curved shape of a child’s Eustachian tube causes fluid to build up and bacteria and viruses can grow in this fluid (NY Amsterdam News). These infections, if gone untreated, can lead to major hearing issues later in life. The most common method of discovering these infections is using an otoscope during routine checkups.

Cost of Delivery

High quality technology costs a lot of money and can sometimes consume a large amount of energy and power. In rural areas, the access to power sources is limited at best and having technology that can be solar powered or even manually powered can be essential to the success of a product. In this case, ultrasound devices are made with expensive technology and can be quite expensive. A recent study did an economic survey on the cost of medical devices (Schreyogg 2009). The analysis was done in European countries and demonstrated that the lower income countries spent less money on medical technology and also had less access to high quality healthcare.

Figure 4 has a breakdown of the money spent on healthcare and medical devices in European countries based on country GDP. What can clearly be seen from this figure is that lower income countries need lower cost devices in order to be able to afford the same quality healthcare found in high income countries. These figures describe the need and limited access to affordable medical devices. Dissemination of a manually powered otoscope in rural areas would help improve child health globally.

Background Information

Lack of access to a necessary medical diagnostic tool is a severe medical problem. Otoscopes are essential for diagnosing ear infections and child health issues early on in medical exams. Power sources are a key limitation on the dissemination of otoscopes in extremely rural areas. Health workers may be unable to take such devices to rural villages where power sources like batteries or wall sockets are unavailable. The technology that can be used to counter such inadequacies is a manual power

Figure 3 (Gorcsan 2004)

Figure 4 (Schreyogg 2009)

generator. By building a portable power source, the power problem can be eliminated completely. Using the properties of magnetic fields and their effects on copper coil inductors, a design for a power generator can be easily created. The movement of a magnetic field across copper wires causes current to flow through the wire and creates a voltage difference between the two ends of the coil. This voltage difference can then be used to power small devices, depending on the power consumption of the device.

Current Technology

The current state of the otoscope industry has one main source of otoscopes. Welch-Allyn is the main producer of these devices and has the most variety. The issue with many of their otoscopes, however, is the fact that the bulb is a halogen bulb. Replacement of a burnt out halogen bulb can cost more than replacing the entire device completely. In addition, most of their otoscopes are made of stainless steel, which is quite expensive and is not affordable for rural health workers. These devices can cost upwards of $150 (Welch-allyn.com). The cheaper lines are made of plastic and can cost around $26, but these still run on batteries, which are hard to find in extremely rural villages.

Hand powered generators have no become common for powering LEDs. One common area where this technology is used, is in the flashlight industry. There are many flashlights that now run using hand-crank generators, which power the LEDs. Such products range from $5 to $400, but the power generation part is quite cheap. In fact, the crank used to power these flashlights can be removed and used to power something else, say an LED in an otoscope.

Product Design

The design of the manually powered otoscope includes a cheap plastic exterior for the handle and a wooden hand-crank power generator with a copper coil inductor and rotating magnet.

Welch-Allyn Pocket Scope

Hand-crank FlashlightMeritline.com

Figure 5 is an example of a hand-crank power generator. A magnet is rotated at the ends of a makeshift inductor to create a current and voltage difference at each end of the inductor. The voltage difference and current will then be used to power the LED in the otoscope. The initial design will have the current rectified and go directly to power the LED. Further design changes could bring about usage of the generator to charge multiple otoscopes at once.

The circuitry for the otoscope includes an LED, a power source, a resistor and a capacitor. The power source charges the capacitor which discharges into the LED and resistor, causing the LED to light up. Because this particular design has a hand-crank generator that provides alternating current, we can use a diode to rectify the source to give DC power to the capacitor.

Figure 6 is a basic circuit diagram for the otoscope. With a manual power source, the only limiting part of this device is the life of the LED. Currently, there are LEDs that can last for a long time without burning out. Effectively, the circuit will work without fail for months, if not years as long as the resistor is high enough to reduce the strain on the LED.

Power Source

Diode

Capacitor LED

Resistor

Figure 5

Figure 6

(1) (2)

(3) (4)

CAD Drawings of the Otoscope: (1) Lens Holder, (2) Ear Piece, (3) Assembled Otoscope, (4) Rapid Prototyped Otoscope

The power source, as described earlier, is built with a magnet and coiled copper wire. The copper is coiled around a 6 inch nail, which is secured in a two-by-four. Perpendicular to the head of the nail, the magnet is oriented in a manner that allows the poles to rotate with respect to the head of the nail. As the magnet rotates, the magnetic field caused by the poles moves across the head of the nail. This causes current to flow through the copper coils and the circuit above.

Figure 7

Figures 7 through 9 show the implemented power source design. Figure 7 shows the whole device, including power source and circuitry. 8 and 9 are views of the magnet-coil apparatus. As the magnet head rotates, current flows through the coil and into the circuit. The capacitor in the circuit charges and then lights an LED in the otoscope shown in the CAD drawings above.

Results

The circuit for the system consisted of a 1 Farad capacitor and a 1 kOhm resistor. The copper coil was made with 32 gauge enameled copper wire and made with 1200 turns. The magnet used was a E825 magnet with 3 lbs of pull. Using the specifications of the design, the power source was built and tested. During the testing, it was discovered that the power source was able to create only a maximum of 50 mV of voltage difference. This made it very difficult to adequately charge the capacitor and light the LED. Some reasons as to the failure of the device include too much space between the magnet and the head of the nail, too little coiling of the copper wire and a weak magnet. With such a low amount of voltage difference generated, the otoscope was not powered adequately and the implementation would not be functional in any setting. In order to adequately charge the capacitor, the power source would need to create a voltage difference of at least 3 volts. Based on the possible sources of error, we can see that the magnet and coil solution is not a reliable method for power generation.

The results of the testing on the device provide validation that power can indeed be generated using a magnet and copper coil in the design described. However, due to the difficulty of properly coiling wire and placement of the copper coil close to the magnet, the design is not a practical solution to the medical problem. A better solution would be to use a 5 volt motor instead of rotating a magnet. Rotating the motor end would cause current to flow and be an adequate replacement for the magnet-coil combination. Additionally, small 5 volt motors are inexpensive and could even reduce the cost of the device from copper coils.

Acknowledgements

There were a number of people who helped complete this project. Heather Benz was instrumental in the creation and evaluation of the magnet-coil system. Chris Browne provided copper coil and help with the circuitry. Mehdi Rahman helped develop the capacitor circuit for charging and discharging power.

Figure 8 Figure 9

References

1. World Health Organization – Global Health Risks2. Welch-Allyn.com3. Nohynek, H. , Madhi, S. , & Grijalva, C. (2009). Childhood Bacterial Respiratory Diseases: Past,

Present, and Future. Pediatric Infectious Disease Journal. 28(10 (Supplement)):S127-S132, 2009. 4. “Overcoming Problems in the Practice of Public Health Among Tribals of India.” Bala,

Soudarssanane and Thiruselvakumar D. Indian Journal of Community Medicine. Vol 34, Issue 4 pp 283-7. Oct 2009.

5. Gorcsan, J, P Pandey, and LE Sade. "Influence of Hand-carried Ultrasound on Bedside Patient Treatment Decisions for Consultative Cardiology." Journal of the American Society of Echocardiography, 17.1 (2004): 50-55.

6. Schreyogg, Jonas, Michael Baumler, and Reinhard Busse. "Balancing Adoption and Affordability of Medical Devices in Europe." Health Policy, 92.2/3 (2009): 218-224.

7. "Guide to Causes and Treatment of Top Childhood Illnesses." New York Amsterdam News, 100.1 (2009): 30-36.