A Four Parameter Microfluidic Tandem SAW-IS Bio-Sensor

Surface Acoustic Resonance (SAR) biosensing has recently been proposed as a highly compact and robust alternative to the conventional SAW delay-line based biosensing. The device can also be presented as a one-port high frequency alternative to the QCM, employing SAW resonance. It enables simple one-port measurements at low powers, while offering robust integration with microfluidics and implementation in integrated sensor arrays. Here we discuss the SAR approach as a key enabling and demonstrate its integration with the impedance spectroscopy (IS) concept in a single microfluidic device. The IS is integrated within a SAW reflector formed as interdigitated electrode (IDE) capacitor. A test fixture with SAW and IS ports is designed and fabricated. Four sensitive parameters are deduced from the tandem sensor readout and employed in a proof of principle study of liposome layers and their interaction with Ca2+ ions.