Bioinspired, uncooled chitin photomechanical sensor for thermal infrared sensing

We have designed and fabricated a novel, polymer-ceramic bimorph infrared (IR) sensing element for uncooled operations. The developed sensors utilize biopolymer chitin on ceramic beams, which deflect with changing temperature due to the mismatch in thermal expansion coefficients of the two materials. This is the first known instance of a polysaccharide-based material used in the development of IR sensors. To maximize the bi-material bending effect, a thin layer of chitin is deposited onto a stiff layer of polysilicon. As in nature, chitin makes an ideal absorbing layer for the sensors because of its high thermal expansion coefficient and natural vibrational resonances in the IR range. Experiments using finite element analysis (FEA) simulation showed that the sensitivity of the polymer-ceramic bimorph sensor was 50 times of the sensitivity of the commonly-used metal-ceramic bimorph sensor. The proposed device offers high sensitivity and significant cost savings compared to existing competitive technologies.