A Radiation Nose for monitoring radiation in space missions

This project developed a radiation monitoring system using conventional silicon CMOS (complementary metal oxide semiconductor) chip except by replacing the silicon dioxide dielectric with a liquid dielectric. Radiation detectors should be capable of discriminating various radiation sources at room temperature with a good energy resolution and amenable to different platforms such as handheld, benchtop, and portals for ports and airports. Current technologies including 3He detectors, scintillators, and solid-state detectors are bulky and expensive. We developed a new radiation detection method and architecture. Some liquids react to radiation exposure with a change in molecular structure, leading to a change in properties such as dielectric constant and polarization. Inspired by such responsivity of liquids, we constructed a transistor with a radiation-responsive liquid as a gate dielectric replacing the conventional oxide gate layer. The current voltage characteristics of the liquid gate dielectric transistor change upon exposure to any type of radiation. Different types of liquids that specifically interact with various target radiations can be used in an array of transistors serving as a radiation nose to discriminate different radiation sources. Moreover, the fluidity of the liquid facilitates the exchange of the damaged liquid with fresh liquid after some time, allowing a reusable sensor. Selection of liquid-state gate dielectric is important for an acceptable device performance, and the choice should satisfy the following requirements: insulating properties, proper dielectric constant, dielectric strength, thermal stability, high purity, low moisture absorption, low viscosity, and responsive to radiation. Preliminary results from this project include detection of gamma radiation. Future work would include development of a radiation nose capable of detecting multiple types of radiation with energy discrimination. More »