Acoustic tweezers: Achieving quasi-dynamic micropartcile patterning using tunable surface acoustic waves

Here we develop a method for quasi-dynamically patterning micron-scale particles in solutions utilizing standing surface acoustic waves (SSAWs). Slanted finger interdigital transducers (SFITs), instead of commonly used uniform interdigital transducers (IDTs), are used to generate SAWs based on the property that the position and wavelength of the excited SAWs is dependent on the frequency of the input AC signal. Since the location and period of particle patterning are dependent upon the position and wavelength of excited SAWs, respectively, they can be dynamically adjusted by tuning the input frequency. In this work, dynamic one-dimension (1D) and two-dimension (2D) micro-particle patterns were obtained using pairs of SFITs. This quasi-dynamic patterning method has advantages such as miniaturization, low power intensity, non-invasiveness, and high speed.