A liquid crystal polymer membrane MEMS sensor for flow rate and flow direction sensing applications

Abstract

The paper reports the design, fabrication and experimental results of a liquid crystal polymer (LCP) membrane-based pressure sensor for flow rate and flow direction sensing applications. Elaborate experimental testing results demonstrating the sensors' performance as an airflow sensor have been illustrated and validated with theory. MEMS sensors using LCP as a membrane structural material show higher sensitivity and reliability over silicon counterparts. The developed device is highly robust for harsh environment applications such as atmospheric wind flow monitoring and underwater flow sensing. A simple, low-cost and repeatable fabrication scheme has been developed employing low temperatures. The main features of the sensor developed in this work are a LCP membrane with integrated thin film gold piezoresistors deposited on it. The sensor developed demonstrates a good sensitivity of 3.695 mV (ms−1)−1, large operating range (0.1 to >10 ms−1) and good accuracy in measuring airflow with an average error of only 3.6% full-scale in comparison with theory. Various feasible applications of the developed sensor have been demonstrated with experimental results. The sensor was tested for two other applications—in clinical diagnosis for breath rate, breath velocity monitoring, and in underwater applications for object detection by sensing near-field spatial flow pressure.

Biomimetic Survival Hydrodynamics and Flow Sensing

“…Targeting real-time flow sensing on unmanned underwater vehicles, Kottapalli et al (2011Kottapalli et al ( , 2012aKottapalli et al ( ,b, 2013; Coombs et al (2014); Miao et al (2013); Asadnia et al (2013a,b);Fernandez et al (2011b), and Dusek et al (2013) adapted a bio-inspired approach, eliminating the fragile haircell element of the sensor and developed lateral-line inspired flexible arrays of polymer MEMS sensors, and self-powered piezoelectric sensors. Polymer sensors were developed using liquid crystal polymer (LCP) as a sensing membrane material, because it is far more robust for underwater applications than silicon (Kottapalli et al 2011;Miao et al 2013;Kottapalli et al 2011Kottapalli et al , 2012a.…”

“…Polymer sensors were developed using liquid crystal polymer (LCP) as a sensing membrane material, because it is far more robust for underwater applications than silicon (Kottapalli et al 2011;Miao et al 2013;Kottapalli et al 2011Kottapalli et al , 2012a. The haircells (less than 1 mm in height) did not extend beyond the boundary layer generated by the flow (Chen et al 2007;Dagamseh et al 2012Dagamseh et al , 2013.…”

Development of a fiber-based membraneless hydrogen peroxide fuel cell

“…In the liquid crystal state, crystal-like regularities are formed as rigid segments of the molecules align next to one another in the direction of the shear ow; this structure remains even aer cooling below the melting point. 25,26 LCP possesses superior electrical and mechanical properties and features a relative dielectric constant of 3 in the range from 0.5 to 40 GHz and a low loss factor of about 0.004. 27 The tensile modulus and tensile strength of LCP exists in ranges of 10 to 24 GPa, and 125 to 255 MPa respectively.…”

Biomimetic hydrogel-CNT network induced enhancement of fluid-structure interactions for ultrasensitive nanosensors

“…[4][5][6][7] To improve the sensitivity of these artificial MEMS sensors, biomimetic approaches have been investigated to mimic the specialized structures of the neuromast, such as the cupula. In the microfabricated sensors, the cupula and cupular fibrils have been mimicked by using hydrogel capping and electrospun micro/nano fibers, respectively.…”