STTR Phase I: A Personal Radiation Dosimeter Using Solid State Tissue Equivalent Detector Technology (SSTED)

The broader impact of this Small Business Technology Transfer (STTR) Phase I project includes both societal and economic benefits. Upon successful completion, the project will introduce a new type of radiation protection monitor or dosimeter that would be worn by individuals that are potentially exposed to ionizing radiation (like x-rays). Typically, this includes health care workers, nuclear energy workers, soldiers, and first responders. This new dosimeter measures human exposure more accurately because it reacts to radiation the same way that human tissue responds. This is referred to as tissue equivalence, and it represents breakthrough technology in radiation monitoring. The promise of tissue equivalent detection at an affordable price allows for improved and efficient dose management for radiation workers, safer medical procedures, broader acceptance of atomic energy sources, novel screening and efficient monitoring for the military, and better situational awareness for first responders. Additionally, the new dosimeters, called Solid State Tissue Equivalent detectors or SSTEDs, are made from completely organic materials using more modern fabrication techniques. Overall, this reduces the cost per unit of a typical dosimeter. From an economic standpoint, the introduction of SSTEDs will create jobs in a new technology sector while decreasing the cost of radiation monitoring. This proposed project will optimize the design of the current Solid State Tissue Equivalent Detector (SSTED) configuration to overcome the one remaining significant technical challenge. Organic semiconductor devices respond well to ionizing radiation. Unfortunately, the physical bond that joins a device's active region to its biasing electronics also may respond to radiation. The response of organic semiconductor devices to ionizing radiation is tissue equivalent because the semiconductor has an equivalent radiation cross section to that of tissue. The bond is not organic, and therefore does not respond with a tissue equivalent response. The project will determine whether design parameters within the organic device itself can be adjusted to mask the bond response. To accomplish this, devices with varying active region thicknesses and geometries will be fabricated and entire devices and their associated supporting electronics and bond regions will be probed with a narrow radiation beam to characterize the contribution to the response of each sub-region within the device and supporting structures. This will answer the question "can a set of design parameters be optimized that will remove bond response from the radiation measurement?" determining whether a compensating design scheme that cancels out the bond response must be employed. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.