A Piezoelectric Flexural Plate Wave (FPW) Bio-MEMS Sensor with Improved Molecular Mass Detection for Point-of-Care Diagnostics

Christian Walk,Karsten Seidl,Andreas Jupe,Michael Görtz,Matthias Wiemann,Jens Weidenmüller

doi:10.1515/cdbme-2019-0067

Abstract

Abstract A piezoelectric FPW-sensor has been developed for a point of care device in this work. The Bio- MEMS FPW-sensor consists of an electrode configuration termed as an interdigital transducer (IDT) placed on a membrane. An input IDT excites and an output IDT detects the propagating acoustic waves through a PZT layer. Design optimizations and fabrication improvements of the FPW-sensor led to significantly reduced attenuation of the wave signal and the damping of the propagating waves between the IDTs. The working principle of mass loading is shown using different low-viscous liquids. A densitydependent sensitivity of -0.39 MHz/g/cm³ was evaluated. After the membrane was functionalized, the Bio-MEMS FPW-sensor was used to measure a specific chemokine in complex solution. By design improvements, the resolution was significantly increased from 0.7 Hz/nM to 14 Hz/nM.

Highlights

The Respiratory Syncytial Virus (RSV) is responsible of a high rate of post-neonatal deaths
A piezoelectric Bio-MEMS Flexural Plate Wave (FPW)-sensor has been developed for a point of care device
The FPW-sensor consists of a particular electrode configuration termed as an interdigital transducer (IDT)

Summary

Introduction

The Respiratory Syncytial Virus (RSV) is responsible of a high rate of post-neonatal deaths. The FPW-sensor consists of a particular electrode configuration termed as an interdigital transducer (IDT). The input IDT, with the aid of underlying piezoelectric layer, is used for the excitation and the output IDT for the detection of the propagating acoustic waves. In prior publications the results of a first design variant (design "1") were presented, which had an extra oxide layer between metal and PZT layer [5]. An oxide layer between the metal layers and the PZT was removed in order to increase the coupling. By replacing the oxide with a TiW layer the suppression of electron drift is appropriate and allows for a high signal integrity. One photolithographic layer could be removed as TiW can be etched together with the metal above

Sensing mechanism of BioMEMS FPW-sensor

15.86 TRIS pump rate

Results of functionalized BioMEMS FPW-sensor

Conclusion