QEL proposes to construct a tissue equivalent microdosimeter using a solid state tissue equivalent detector (SSTED). The Phase I study will produce the working SSTEDs and the Phase II will provide a viable completed microdosimeter. An organic semiconductor device based on QEL's novel design is described. The expected electrical properties of the device both in the quiescent state and under exposure are calculated. The fabrication process is described in detail and the supporting electronics are defined as well. A complete set of tests that will determine the feasibilty of the SSTEDs is defined. The first test will determine if the detectors' response matches the expected response based on detector geometry. The subsequent tests will determine the sensitivity, calibration factors, and tissues equivalence of the fabricated devices.