Integrated functions of microfluidics and gravimetric sensing enabled by piezoelectric driven microstructures

Micro- and nano-electromechanical Systems resonators have been regarded as powerful tools for precision mass detection, and their abilities to measure these in a liquid environment open various opportunities for biosensing, chemical analysis, and environmental monitoring. Apart from overcoming issues of fluidic damping and electrical interfaces, there is a great challenge of bringing microanalytes to these devices with the required precision and scaling for high throughput sensing. Herein we address the above challenges by proposing a self-excited localized acoustic manipulation methodology based on a piezoelectric micromechanical diaphragm resonator (PMDR). Such the PMDR integrates acoustofluidics and mass sensing functions in tandem on a single device. Particle enrichment is realized within tens of seconds and the limit of detection is enhanced by mitigating common issues such as low capture rate and non-uniform distribution. The developed PMDR is versatile in its applicability to a range of particle sizes and densities for both acoustofluidic actuation and in-situ mass sensing. This work addresses long term technical challenges of inaccurate and inefficient measurement of liquid phase resonance mass sensing with great application potentials in biochemical detection and environmental monitoring.