Abstract
Resonant biosensors are known for their high accuracy and high level of miniaturization. However, their fabrication costs prevent them from being used as disposable sensors and their effective commercial success will depend on their ability to be reused repeatedly. Accordingly, all the parts of the sensor in contact with the fluid need to tolerate the regenerative process which uses different chemicals (H3PO4, H2SO4 based baths) without degrading the characteristics of the sensor. In this paper, we propose a fluidic interface that can meet these requirements, and control the liquid flow uniformity at the surface of the vibrating area. We study different inlet and outlet channel configurations, estimating their performance using numerical simulations based on finite element method (FEM). The interfaces were fabricated using wet chemical etching on Si, which has all the desirable characteristics for a reusable biosensor circuit. Using a glass cover, we could observe the circulation of liquid near the active surface, and by using micro-particle image velocimetry (μPIV) on large surface area we could verify experimentally the effectiveness of the different designs and compare with simulation results.
Highlights
Piezoelectric devices, such as bulk acoustic wave (BAW) or surface acoustic wave (SAW) devices, have started to be used successfully for biosensing purposes
The high level of miniaturization brings its share of drawbacks
The piezoelectric resonant sensor is built with glass wafer instead of the piezoelectric material (GaAs), a piezoelectric material where the grafting process with thiolate is comparable to grafting on gold, for which many analytes are readily available
Summary
Piezoelectric devices, such as bulk acoustic wave (BAW) or surface acoustic wave (SAW) devices, have started to be used successfully for biosensing purposes. They exhibit high sensitivity in mass [1,2], in viscous/viscoelastic changes [3,4], as well as in the detection of conformational changes of surface-bound biomolecules for better understanding of biomolecular interactions [5,6]. It is hard to integrate in these materials the microchannels and chamber needed for the manipulation of fluids at such a small scale To circumvent these two issues, we will describe a microfluidic interface that can be integrated within a reusable piezoelectric sensor, for bringing biofluids in contact with the sensitive surfaces (Figure 1)
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