Sensors 2011, 11(2), 1810-1818; doi:10.3390/s110201810
Communication

Optically Defined Modal Sensors Incorporating Spiropyran-Doped Liquid Crystals with Piezoelectric Sensors

Kuan-Ting Chen 1 email, Chin-Kai Chang 2 email, Hui-Lung Kuo 2 email and Chih-Kung Lee 1,3,4,* email
1 Engineering Science & Ocean Engineering, National Taiwan University, Taipei, 10617, Taiwan 2 Industrial Technology Research Institute (ITRI), Materials & Chemical Research Laboratory, Hsinchu, 31040, Taiwan 3 Institute of Applied Mechanics, National Taiwan University, Taipei, 10617, Taiwan 4 Institute for Information Industry, Taipei, 10622, Taiwan
* Author to whom correspondence should be addressed.
Received: 8 December 2010; in revised form: 25 January 2011 / Accepted: 26 January 2011 / Published: 31 January 2011
(This article belongs to the Section Physical Sensors)
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Abstract: 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.
Keywords: piezoelectric; liquid crystal; spiropyran; cantilever beam; modal sensor; optically defined

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Cite This Article

MDPI and ACS Style

Chen, K.-T.; Chang, C.-K.; Kuo, H.-L.; Lee, C.-K. Optically Defined Modal Sensors Incorporating Spiropyran-Doped Liquid Crystals with Piezoelectric Sensors. Sensors 2011, 11, 1810-1818.

AMA Style

Chen K-T, Chang C-K, Kuo H-L, Lee C-K. Optically Defined Modal Sensors Incorporating Spiropyran-Doped Liquid Crystals with Piezoelectric Sensors. Sensors. 2011; 11(2):1810-1818.

Chicago/Turabian Style

Chen, Kuan-Ting; Chang, Chin-Kai; Kuo, Hui-Lung; Lee, Chih-Kung. 2011. "Optically Defined Modal Sensors Incorporating Spiropyran-Doped Liquid Crystals with Piezoelectric Sensors." Sensors 11, no. 2: 1810-1818.

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