A tritium-based photovoltaic power source is introduced as a long-lived power source for sensor networks (15 yrs. operational lifetime). We chose tritium as a benign and low-cost isotope. We present our tritium emitter in an indirect-converter design that mates a phosphor (beta to optical converter) to a commercial PV cell (photon to electrical converter). We use this system to provide a direct current of at least 30uA to a sensor payload.  The tritium, phosphor and PV are sealed in a NRC-approved military battery (BA5590) with connector and container.  This DC energy feeds the 100uW sensor electronics payload. We designed the sensor to detect radiation levels in the energy range of 400 keV to 2 MeV. The electronics in the sensor employ a low-power scintillator-photodiode sensor and a low self-leakage ultra-capacitor coupled to a nano-power microprocessor.  By incorporating best practices in energy-efficient circuit design, the sensor can operate over the lifetime of the isotope source.  This sensors detects small changes in background radiation; a 20 �Ci source of 137Cs can be detected out to a distance of ~three meters (9 ft.). The microprocessor controlled APD, discriminator and counting circuits all together operate within the 100uW average power window of the isotope power source. We believe that this low-cost approach is the ideal trajectory for the development of low-cost long-lived compact electronics and sensor applications for battlefield and environmental detection.

Tritium power source matched for long-lived sensors

247th National Meeting (2014)

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