New micro-drum device overcomes traditional challenges to ultrasensitive detection in liquids

Micro- and nano-electromechanical resonators exhibit an extraordinary ability to detect traces of microanalytes at concentrations much lower than typical methods. However, they cannot be readily used in liquids, which dampen these resonators and render the signal undetectable. Qian et al. developed a sub-millimeter micro-electromechanical resonator with significantly higher sensitivity in liquids by using acoustics.

To measure particle mass within a liquid, the team’s device generates acoustic waves by vibrations like a tiny drum to cluster particles at target sites within a radius of 0.25 millimeters. The shifts in natural frequency of the device are then correlated to the particle mass. Notably, the device is much smaller and required less power than similar existing devices that also evoke acoustic waves.

“A big advantage of our device and approach is that is completely label-free and does not require pre-treatment, in contrast to many existing detection platforms,” author Joshua Lee said. “The key challenge was designing a device that could generate the required acoustic fields, and not be too severely damped by the fluid to render electrical detection impossible while also being sensitive to particle mass loading.”

The team fabricated the device using a standard silicon-based process for creating micro-electromechanical systems. The silicon drum was overlaid with a piezoelectric film to form a transducer that generates oscillations. The oscillations interacted with the fluid to pull particles onto target sites on the device, sites where the frequency perturbation are most sensitive.

The team plans to explore the physical mechanisms underlying the device to improve its sensitivity. Potential topics include interactions between the detection device, the particles being detected, and the fluid containing the particles.

Source: “Integrated functions of microfluidics and gravimetric sensing enabled by piezoelectric driven microstructures,” by Jingui Qian, Yue Wang, Yuhang Xue, Habiba Begum, Yong-Qing Fu, Joshua E.-Y. Lee, Applied Physics Reviews (2025). The article can be accessed at https://doi.org/10.1063/5.0225891 .