TY - JOUR
T1 - A novel langasite crystal microbalance instrumentation for UV sensing application
AU - Saha, Tridib
AU - Guo, Ningqun
AU - Ramakrishnan, N.
N1 - Funding Information:
This work was performed in part at the Melbourne Centre for Nanofabrication (MCN) in the Victorian Node of the Australian National Fabrication Facility (ANFF). This work was supported by the Ministry of Higher Education, Malaysia under Grant FRGS/2/2014/SG02/MUSM/03/1 . The authors also thank Monash University Malaysia 2015-CRC-ILL grant for supporting the infrastructure.
Publisher Copyright:
© 2016 Elsevier B.V.
Copyright:
Copyright 2017 Elsevier B.V., All rights reserved.
PY - 2016/12/1
Y1 - 2016/12/1
N2 - In this paper, we present a novel low-power UV sensor instrumentation based on ZnO thin-film and langasite crystal microbalance (LCM) composite resonator. The design of this sensor utilizes the exceptional transient response characteristics of thickness shear mode langasite crystal and UV sensitivity of annealed ZnO thin film. Our comparative transient analysis of langasite and quartz crystals shows that langasite crystal has high stability and fast relaxation times, and requires a fraction of excitation power in comparison to that of quartz. Upon investigating the equivalent circuit components, we discovered that high value of motional capacitance of LCM resulted in these contrasting transient responses in LCM and QCM. This high motional capacitance can be further attributed to the high electromechanical coupling coefficient (K2) of piezoelectric langasite crystal. Motivated by these observed characteristics, we proposed a novel sensor instrumentation that is simple yet effective in simultaneous measurements of the frequency, dissipation factor, and the amplitude of oscillation of a LCM. Moreover, our measurements allow for direct monitoring of any change in piezoelectricity of ZnO thin film. Our new measurement approach uses a one-shot pulse instead of conventional sinusoidal waveform to drive the crystal, which allows for simple instrumentation and requires very low input power. The transient response of the crystal shows that the crystal oscillates at its fundamental frequency and the amplitude of oscillation decays exponentially. From the recorded decay curve, the frequency of the freely oscillating crystal, and other important crystal parameters were calculated. We have utilized this mechanism to demonstrate highly sensitive ZnO thin film and LCM based UV sensor. Highest sensitivity of 35.8 ppm per μW/cm2 was observed for the LCM coated with 400 nm ZnO film. Additionally, the influence of UV on the piezoelectric output of ZnO thin film was also characterized by monitoring the DC offset of the output oscillations. Our findings in this work opens scope for developing low-power acoustic sensors with significant implications towards self-powering sensors.
AB - In this paper, we present a novel low-power UV sensor instrumentation based on ZnO thin-film and langasite crystal microbalance (LCM) composite resonator. The design of this sensor utilizes the exceptional transient response characteristics of thickness shear mode langasite crystal and UV sensitivity of annealed ZnO thin film. Our comparative transient analysis of langasite and quartz crystals shows that langasite crystal has high stability and fast relaxation times, and requires a fraction of excitation power in comparison to that of quartz. Upon investigating the equivalent circuit components, we discovered that high value of motional capacitance of LCM resulted in these contrasting transient responses in LCM and QCM. This high motional capacitance can be further attributed to the high electromechanical coupling coefficient (K2) of piezoelectric langasite crystal. Motivated by these observed characteristics, we proposed a novel sensor instrumentation that is simple yet effective in simultaneous measurements of the frequency, dissipation factor, and the amplitude of oscillation of a LCM. Moreover, our measurements allow for direct monitoring of any change in piezoelectricity of ZnO thin film. Our new measurement approach uses a one-shot pulse instead of conventional sinusoidal waveform to drive the crystal, which allows for simple instrumentation and requires very low input power. The transient response of the crystal shows that the crystal oscillates at its fundamental frequency and the amplitude of oscillation decays exponentially. From the recorded decay curve, the frequency of the freely oscillating crystal, and other important crystal parameters were calculated. We have utilized this mechanism to demonstrate highly sensitive ZnO thin film and LCM based UV sensor. Highest sensitivity of 35.8 ppm per μW/cm2 was observed for the LCM coated with 400 nm ZnO film. Additionally, the influence of UV on the piezoelectric output of ZnO thin film was also characterized by monitoring the DC offset of the output oscillations. Our findings in this work opens scope for developing low-power acoustic sensors with significant implications towards self-powering sensors.
KW - Electrical equivalent circuit
KW - Langasite crystal microbalance
KW - Sensor instrumentation
KW - Transient response
KW - UV sensing
KW - ZnO thin film
UR - http://www.scopus.com/inward/record.url?scp=84994026380&partnerID=8YFLogxK
U2 - 10.1016/j.sna.2016.10.024
DO - 10.1016/j.sna.2016.10.024
M3 - Article
AN - SCOPUS:84994026380
SN - 0924-4247
VL - 252
SP - 16
EP - 25
JO - Sensors and Actuators, A: Physical
JF - Sensors and Actuators, A: Physical
ER -