Organic radiation detectors for real-time dosimetry

Here, we report on an all-organic solid-state radiation dosimeter patterned onto a plastic substrate that allows for real-time measurements communicated over WiFi. The “sense” area and the conductive traces are made using low-conductivity PEDOT:PSS, and measurements are read out by a low-current op-amp. As the detector is subjected to radiation, the ionized air, substrate, and sense area cause a charge accumulation which is then read out as a voltage from the op-amp. OFETs on either side of the sense area allow for the charge to be cleared, allowing for accurate dose measurement without saturation. Additionally, the inclusion of a PEDOT:PSS ground plane as the first layer on the PEN substrate helps to shield the sensor itself from extraneous static. For X-rays, the limit of detection is approximately 5 mRad/min, and for gamma rays the limit is approximately 5 mRad/hr. Through appropriate control of the clearing OFETs, the device is quickly reset to allow for a continuous measurement.