Tear fluid offers a potential route for non-invasive sensing of physiological parameters. Utilization of this potential
depends on the ability to manufacture sensors that can be placed on the surface of the eye. A contact lens makes a natural
platform for such sensors, but contact lens polymers present a challenge for sensor fabrication. This paper describes a
microfabrication process for constructing sensors that can be integrated into the structure of a functional contact lens in
the future. To demonstrate the capabilities of the process, an amperometric glucose sensor was fabricated on a polymer
substrate. The sensor consists of platinum working and counter electrodes, as well as a region of indium-tin oxide (ITO)
for glucose oxidase immobilization. An external silver-silver chloride electrode was used as the reference electrode
during the characterization experiments. Sensor operation was validated by hydrogen peroxide measurements in the 10-
20 μM range and glucose measurements in the 0.125-20 mM range.
We present the application of Drosophila fruit flies as an unconventional substrate for microfabrication. Drosophila by itself represents a complex system capable of many functions not attainable with current microfabrication technology. By using Drosophila as a substrate, we are able to capitalize on these natural functions while incorporating additional functionality into a superior hybrid system. In the following, development of microfabrication processes for Drosophila substrates is discussed. In particular, results of a study on Drosophila tolerance to vacuum pressure during multiple stages of development are given. A remarkable finding that adult Drosophila may withstand up to 3 hours of exposure to vacuum with measurable survival is noted. This finding opens a number of new opportunities for performing fabrication processes, similar to the ones performed on a silicon wafer, on a fruit fly as a live substrate. As a model microfabrication process, it is shown how a collection of Drosophila can be made to self-assemble into an array of microfabricated recesses on a silicon wafer and how a shadow mask can be used to thermally evaporate 100 nm of indium on flies. The procedure resulted in the production of a number of live flies with a pre-designed metal micropattern on their wings. This demonstration of vacuum microfabrication on a live organism provides the first step towards the development of a hybrid biological/solid-state manufacturing process for complex microsystems.