A miniaturised autonomous sensor based on nanowire materials platform: the SiNAPS mote

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Koshro Pour, Naser
Kayal, M.
Jia, G.
Eisenhawer, B.
Falk, F.
Nightingale, Adrian M.
DeMello, John C.
Georgiev, Yordan M.
Petkov, Nikolay
Holmes, Justin D.
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Society of Photo-optical Instrumentation Engineers (SPIE)
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A micro-power energy harvesting system based on core(crystalline Si)-shell(amorphous Si) nanowire solar cells together with a nanowire-modified CMOS sensing platform have been developed to be used in a dust-sized autonomous chemical sensor node. The mote (SiNAPS) is augmented by low-power electronics for power management and sensor interfacing, on a chip area of 0.25mm2. Direct charging of the target battery (e.g., NiMH microbattery) is achieved with end-to-end efficiencies up to 90% at AM1.5 illumination and 80% under 100 times reduced intensity. This requires matching the voltages of the photovoltaic module and the battery circumventing maximum power point tracking. Single solar cells show efficiencies up to 10% under AM1.5 illumination and open circuit voltages, Voc, of 450-500mV. To match the battery’s voltage the miniaturised solar cells (~1mm2 area) are connected in series via wire bonding. The chemical sensor platform (mm2 area) is set up to detect hydrogen gas concentration in the low ppm range and over a broad temperature range using a low power sensing interface circuit. Using Telran TZ1053 radio to send one sample measurement of both temperature and H2 concentration every 15 seconds, the average and active power consumption for the SiNAPS mote are less than 350nW and 2.1 μW respectively. Low-power miniaturised chemical sensors of liquid analytes through microfluidic delivery to silicon nanowires are also presented. These components demonstrate the potential of further miniaturization and application of sensor nodes beyond the typical physical sensors, and are enabled by the nanowire materials platform.
Mote , Silicon nanowires , Chemical sensors , Microfluidics , Energy harvesting , Electronics design , Low power , Heterojunction solar cells , Electron beam resist , Hydrogen silsesquioxane , Solar cells
Pour, N. K., Kayal, M., Jia, G., Eisenhawer, B., Falk, F., Nightingale, A., DeMello, J. C., Georgiev, Y. M., Petkov, N., Holmes, J. D., Nolan, M. and Fagas, G. (2013) A miniaturised autonomous sensor based on nanowire materials platform: the SiNAPS mote. Proceedings of SPIE 8763, Smart Sensors, Actuators, and MEMS VI, Grenoble, France, 24 April. doi:10.1117/12.2017520
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© Copyright 2013 Society of Photo-Optical Instrumentation Engineers. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited. http://dx.doi.org/10.1117/12.2017520