Optically defined modal sensors incorporating spiropyran-doped liquid crystals with piezoelectric sensors.
We integrated a piezoelectric sensing layer lamina containing liquid crystals (LC) and spiropyran (SP) in a LC/SP mixture to create an optically reconfigurable modal sensor for a cantilever beam. The impedance of this LC/SP lamina was decreased by UV irradiation which constituted the underlying mechanism to modulate the voltage externally applied to the piezoelectric actuating layer. Illuminating a specific pattern onto the LC/SP lamina provided us with a way to spatially modulate the piezoelectric vibration signal. We showed that if an UV illuminated pattern matches the strain distribution of a specific mode, a piezoelectric modal sensor can be created. Since UV illumination can be changed in situ in real-time, our results confirm for the first time since the inception of smart sensors, that an optically tailored modal sensor can be created. Some potential applications of this type of sensor include energy harvesting devices, bio-chips, vibration sensing and actuating devices.
Engineering Science & Ocean Engineering, National Taiwan University, Taipei, 10617, Taiwan. ktchen@ntumems.net
Kuan-Ting
KT
Chen
Chin-Kai
CK
Chang
Hui-Lung
HL
Kuo
Chih-Kung
CK
Lee
D001578:Benzopyrans / Q000737:chemistry*; D004560:Electricity; D004563:Electrochemistry / Q000295:instrumentation*; D004566:Electrodes; D007211:Indoles / Q000737:chemistry*; D050866:Liquid Crystals / Q000737:chemistry*; D009574:Nitro Compounds / Q000737:chemistry*; D055620:Optical Phenomena; D017971:Tin Compounds / Q000737:chemistry; D014466:Ultraviolet Rays; D014732:Vibration
D001578:Benzopyrans; D007211:Indoles; D009574:Nitro Compounds; D017971:Tin Compounds; C548873:merocyanine; C088184:spiropyran; C109984:indium tin oxide