Tunable patterning of microscale particles using a surface acoustic wave device with slanted-finger interdigital transducers

Abstract

Polymer-based materials with patterned functional particles have been used to develop smart devices with multiple functionalities. This paper presents a novel method to pattern microscale particles into biocompatible polyethylene glycol diacrylate (PEGDA) fluid through a designed surface acoustic wave (SAW) device with slanted-finger interdigital transducers (SFITs). By applying signals of different frequencies, the SFITs can excite SAWs with various wavelengths to pattern the microscale particles. The structural design and working principle of the SAW device with SFITs are firstly presented. To investigate the generation of standing SAWs and pressure field distributions of the SAW device with SFITs, a numerical model was developed. Simulation results showed that different strip-shape patterned pressure fields can be generated, and the period and width of adjacent strips can be adjusted by changing the frequencies of the excitation signals. Experiments were performed to verify that the microscale particles in the PEGDA solution can be successfully patterned into strip-shape patterns with various positions, periods, and widths. The results obtained in this study demonstrate that the developed method of using an SAW device with SFITs can be used for tunable patterning of microscale particles in solutions, and shows great potential for biomedical and microfluidic applications.