The beetle Melanophila acuminata detects forest fires from distances as far as 80 miles away. To accomplish this, the beetle uses highly specific IR receptors with a diameter of approximately 15 μm. These receptors are mechanoreceptors that detect deformations induced by the absorption of radiation. Although the detection mechanism is understood in principle, it is still unclear how the beetle reaches such high sensitivity. In this work, we present the biomimetic approach of an uncooled IR sensor based on the beetle’s receptors. This sensor is based on a fluid-filled pressure cell and operates at room temperature. Upon absorbing IR radiation, the fluid heats up and expands. The expanding fluid deflects one electrode of a plate capacitor. By measuring the change in capacitance, the volume increase and the absorbed energy can be inferred. To prevent the risk of damage at high energy absorption, a compensation mechanism is presented in this work. The mechanism prevents large but slow volume changes inside the pressure cell by a microfluidic connection of the pressure cell with a compensation chamber. The channel and the compensation chamber act as a microfluidic low-pass filter and do not affect the overall sensitivity above an appropriate cut-off frequency. Using MEMS technology, we are able to incorporate the complete system into a silicon chip with an area of a few mm². Here, we show a proof-of-concept and first measurements of the sensor.

Date Published: 24 June 2014
PDF: 10 pages
Proc. SPIE 9070, Infrared Technology and Applications XL, 90701W (24 June 2014); doi: 10.1117/12.2049144

Published in SPIE Proceedings Vol. 9070:
Infrared Technology and Applications XL
Bjørn F. Andresen; Gabor F. Fulop; Charles M. Hanson; Paul R. Norton, Editor(s)