“Fire-beetles” inspired all-solid infrared sensor with bolometric and photomechanic dual sensing modes

Abstract

By mimicking the structure of the infrared-sensing organs of the “fire-beetles” of genus Melanophilaacuminata, we herein designed and fabricated an all-soild “fire-beetles” inspired infrared sensor, the key components of which is composed of a stress-concentrated photothermal expansion dendrite structure made of polydopamine enabled polydimethylsiloxane nanocomposite elastomer and a highly-sensitive piezoresistive membrane processed by direct laser writing carbonization. Our sensor possesses bolometric and photomechanic dual sensing modes, with the optimal responsivity of −1.4 W−1 and 2.2 W−1, the detection limit of 0.03 mW/√Hz and 0.23 mW/√Hz, as well as the response time of 3.8 s and 2.5 s, respectively. The two-step photothermal and solid mechanics FEA modeling was performed to help understanding its sensing behavior in both bolometric and photomechanic operation modes, which indicates the possibility for orders-of-magnitude improvement on the responsiveness of our “fire-beetles” inspired IR sensor when increasing the bonding strength between the photothermal dendrite tip and the piezoresistive sensing membrane. The all-solid nature and the piezoresistive read-out scheme as well as its good performance make our sensor valuable for low-cost IR sensing applications.