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Proceedings Paper

Microfabricated self-resonant structure as a passive wireless chemical sensor
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Paper Abstract

This paper describes ongoing work to develop a low cost, passive wireless chemical sensor using a microfabricated inductor with interdigitated capacitors (IDC). A self-resonant-structure (SRS) is designed by incorporating IDC electrodes in the inter-winding space of the inductor. The distributed IDC capacitance is affected by dielectric constant and conductivity of its environment or material under test (MUT). This serves as a capacitive transducer changing the resonant frequency of the SRS. The SRS is interrogated using a non-contact inductively coupled reader coil. The shift in resonance frequency of the SRS is used to detect material properties of the environment/MUT. The dielectric constant (ε) and conductivity (σ) can be used to provide information about the surrounding environment. The ε and the σ are determined by fitting and extraction from circuit models of the IDC. Relationship between sensor layout and coupling factor between sensor and reader is investigated. Optimizations of the coupling factor based on this relationship are discussed. IDC design trade-offs between the sensor's sensitivity and coupling factor are investigated. The sensor's response to variety of liquid MUTs with a wide range of dielectric constant and conductivity is presented.

Paper Details

Date Published: 5 May 2011
PDF: 8 pages
Proc. SPIE 8066, Smart Sensors, Actuators, and MEMS V, 80661L (5 May 2011); doi: 10.1117/12.886895
Show Author Affiliations
Sheng Zhang, The Univ. of Texas at Austin (United States)
Praveenkumar Pasupathy, The Univ. of Texas at Austin (United States)
Dean P. Neikirk, The Univ. of Texas at Austin (United States)


Published in SPIE Proceedings Vol. 8066:
Smart Sensors, Actuators, and MEMS V
Ulrich Schmid; José Luis Sánchez-Rojas; Monika Leester-Schaedel, Editor(s)

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