Antenna and coil design for wireless signal detection and charging of embedded power active contact lens.

This paper presents a screen printed 2.4 GHz antenna and induction charging coil for an active contact lens with a single large pixel user display and on-board 3.8 V 5 uAh rechargeable battery. The antenna traces are printed using silver conductive paste on a 25 um polyethylene terephthalate (PET) substrate. The incoming signal from the antenna feeds into an IC that amplifies and rectifies the signal. The coil provides wireless energy transfer to inductively charge a thin film battery [1] located on the contact lens. The printed antenna achieved a S11 of -4 dB at 2.4 GHz and a gain of -13 dB.

Using transmission properties to determine blood glucose levels.

A non-intrusive technique based on modeling the body as a transmission channel was tested in vitro and was shown to perform equally with a commercial OTS glucose meter on saline-glucose solutions of concentrations of glucose from 30 to 300 mg/dL. The technique uses an initial frequency sweep to locate a frequency where a resonant response occurs. At that position the phase is changing rapidly and can therefore be used more easily to measure a phase difference. This sweet spot can be natural or assisted. Present efforts are toward a system which uses a feedback amplifier with a low phase margin in order to easily find the the region of rapid phase change. Initial tests measuring known glucose concentrations with an OTS glucose meter and then using the proposed technique were shown to correlate with the actual concentrations with an R(2) = 0.9879 and R(2) = 0.9952 respectively (with one outlier data point removed). Further tests are being conducted in vitro on whether other interfering agents may disrupt results. The ultimate goal of the development of this technique is to fabricate a device that is worn externally on the upper arm and does not require blood for testing. A device is being built and is scheduled for human subject testing in Summer 2013. Some results of human testing may be available at the EMBC conference. Human testing will involve measurements done with our device against an OTS glucose meter and results compared. The future goal is to refine the device so that it can be worn 24 hours a day and will automatically test the wearer at a user specified interval such as 10 or 20 minutes by transmitting a low power signal for a few microseconds. Power levels are still being determined but, in simulation, nano-watts was sufficient for the distance needed to travel which is orders of magnitude less than present day cell phones. To evaluate safety of the system, 3D electromagnetic simulations are being carried out with the device positioned strapped to the upper arm. Simulations show transmission along the targeted paths which suggests that affective glucose sensing is possible with this device.

Making medical devices accessible: a drug-resistant malaria detection system.

People living in areas of the world that are affected by disease, famine, or poverty could have their lives drastically improved by currently available electronic technologies, but the cost, complexity and/or limited operating environments of devices which employ these technologies can make it impossible or impractical for many of those in-need populations to actually acquire and make use of them. The barriers to acquisition and use are understandable. Most medical device companies are located in the wealthier countries, as are their clientele, and, to these companies, taking technological advances and either creating new products, or make their pre-existing products more powerful is the logical business and scientific progression. As such, devices seen in production that would be useful are often hospital grade with high-accuracy and varying amounts of adjustability so as to allow them to be used in performing a variety of functions. But it is exactly this accuracy and flexibility that makes them too expensive and complex to easily be acquired and used in environments that have limited financial and skill resources. In this paper, as an example of how to make presently inaccessible technology accessible, a method of detecting drug-resistant malaria strains in laboratories is analyzed, barriers to use of such a system in a poorer, malaria affected region are looked at, and a device is designed and a prototype built that is simple and affordable. Such a system not only allows collection of epidemiological information, but also empowers doctors and researchers to investigate new drugs without expensive laboratories.