Wavelength-selective optomechanical sensor based on interpenetrating polymer network

This paper presents the development of an optomechanical sensor utilizing an interpenetrating polymer network (IPN) structure, which can be reversibly stimulated by specific wavelengths. The IPN structure consists of polydimethylsiloxane (PDMS) main chain and azobenzene. The deformation due to the trans-cis photoisomerization of azobenzene after light exposure can be counter-balanced by the restoring force of the PDMS network. Therefore, a relatively fast and sensitive mechanical response due to the light exposure can be obtained. The IPN generates the electric signal of the sensor by incorporating with a strain gauge. The sensor is 14*4mm² in area. The largest strain of 7% was obtained when the IPN was exposed to an UV light of 365 nm wavelength and 24 mW power. The strain can be reversibly removed by exposure under green light of 530 nm wavelength and 4 mW power. The strain reduced to 0.05% after the IPN layer was attached to the strain gauge. The presented sensor can be applied in monitoring UV intensity and optomechanical actuation with an electrical readout.