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Sensitivity Analysis of a Portable Wireless PCB-MEMS Permittivity Sensor Node for Non-Invasive Liquid Recognition
Javier Meléndez-Campos1, Matias Vázquez-Piñón1, Sergio Camacho-Leon1
1Tecnologico de Monterrey, School of Engineering and Sciences, Ave. Eugenio Garza Sada 2501, Monterrey 64849, Mexico.
Micromachines
|September 28, 2021
Summary
A new portable wireless sensor node measures liquid permittivity using an interdigitated microelectrode array. This device enables efficient liquid characterization and differentiation for various applications.
Area of Science:
- Materials Science and Engineering
- Electrical Engineering
- Sensor Technology
Background:
- Dielectric characteristics are vital for identifying liquid properties and distinguishing between similar samples.
- Liquid recognition is crucial in fields like healthcare, food science, and quality control.
- Accurate permittivity measurements are key for material characterization and differentiation.
Purpose of the Study:
- To develop and demonstrate a portable wireless sensor node for liquid permittivity measurement.
- To enable characterization and differentiation of liquids using dielectric properties.
- To present a microfabrication technique for creating robust microelectromechanical systems (MEMS) transducers.
Main Methods:
- Fabrication of an interdigitated microelectrode array transducer using laser ablation on a printed circuit board (PCB) substrate.
- Coating the transducer with SU-8 polymer to protect electrodes and prevent sample contamination.
- Modeling the transducer impedance as a Randles cell and determining its components analytically.
- Testing sensor node sensitivity with three transducer designs across four fluids (air, isopropanol, glycerin, distilled water).
Main Results:
- Successful fabrication of a portable wireless sensor node with a microelectromechanical systems (MEMS) transducer.
- Achieved a sensitivity of 1.6965 +/- 0.2028 εr/pF for liquid permittivity measurements.
- Demonstrated the effectiveness of laser ablation for reducing transducer size while maintaining sensitivity.
- The SU-8 polymer coating successfully prevented direct contact, enhancing durability and preventing electrochemical reactions.
Conclusions:
- The developed portable wireless sensor node is effective for liquid characterization and differentiation.
- Laser ablation microfabrication offers a viable method for creating compact and sensitive MEMS transducers.
- The sensor node's design ensures durability and prevents sample contamination, making it suitable for diverse applications.
