Making acoustic tweezers more accessible

Without directly touching them, researchers need to be able to gently move cells or particles to sort, position, and study them for various biomedical and environmental applications. However, traditional acoustofluidic devices, which rely on sound waves to manipulate microparticles, often require complex, expensive fabrication.

Zheng et al. developed a simpler, low-cost method for moving individual or arrayed microparticles. The technique uses standing Scholte waves, a type of interfacial wave that propagates along a solid-liquid boundary, as acoustic tweezers. Stepwise adjustments to the frequency of the applied acoustic signals generates tunable standing Scholte wave patterns that transport and position microparticles within a microfluidic chip with micrometer-scale accuracy.

The device integrates a single piezoelectric transducer with a glass-based microchannel and can be fabricated in a standard lab without cleanroom facilities.

“This work is important because it provides a low-cost, portable, and disposable alternative to conventional acoustofluidic systems, dramatically lowering the barrier to entry,” said author Junjun Lei. “We believe this makes acoustic tweezers more accessible to researchers in fields like biology or chemistry who may not have specialized engineering backgrounds.”

The authors demonstrated that this technique performs similarly to traditional acoustofluidic devices, which rely on surface acoustic waves and bulk acoustic waves, while offering a simpler architecture. This simplicity makes the device well suited for point-of-care diagnostic applications, in which testing is performed where patient care is delivered.

“Because the chip is disposable, it also minimizes cross-contamination risks in clinical use,” Lei said.

Next, the authors plan to extend the technique from stepwise to continuous control, which could enable high-efficiency particle separation and filtration.

Source: “On-chip acoustic manipulation of single or arrayed microparticles via standing Scholte waves,” by Yedong Zheng, Cheng Liu, Feng Cheng, Maodan Yuan, Zhigang Huang, and Junjun Lei, Applied Physics Letters (2026). The article can be accessed at https://doi.org/10.1063/5.0293798 .