Self-Aligned Interdigitated Transducers for Acoustofluidics

Abstract

Abstract:The surface acoustic wave (SAW) is effective for the manipulation of fluids and particles at microscale. The current approach of integrating interdigitated transducers (IDTs) for SAW generation into microfluidic channels involves complex and laborious microfabrication steps. These steps often require full access to clean room facilities and hours to align the transducers to the precise location. This work presents an affordable and innovative method for fabricating SAW-based microfluidic devices without the need for clean room facilities and alignment. The IDTs and microfluidic channels are fabricated using the same process and thus are precisely self-aligned in accordance with the device design. With the use of the developed fabrication approach, a few types of different SAW-based microfluidic devices have been fabricated and demonstrated for particle separation and active droplet generation.

Flexible Printed Circuit Board as Novel Electrodes for Acoustofluidic Devices

“…Ref. [13] also reported a low-cost method to pour a low-melting point metal liquid into an IDT mold made by polydimethylsiloxane (PDMS) to form electrodes. A more accurate manufacturing technique was achieved by clamping a rigid printed circuit board (PCB) with a finger electrode pattern onto a LiNbO3 substrate to make an acoustic tweezer with the ability to manipulate polystyrene microspheres and cancer cells [14].…”

Pressure-Driven Filling of Closed-End Microchannel: Realization of Comb-Shaped Transducers for Acoustofluidics

“…Here, we use 20 finger pairs and two separate microchannels are filled separately. The integrated PDMS microchannel and lithium niobate substrate is fabricated, bonded, and tested as reported in our previous work [17]. We characterize the S 11 measurement of the system using the network analyzer (Keysight technologies, 8753C) (see Appendix A).…”

“…Misalignment results in inappropriate wave propagation [16] at unsuitable locations. In order to circumvent the complex fabrication procedures, we recently demonstrated that microsolidics can be used to fabricate self-aligned IDTs [17] for acoustofluidics. Microsolidics, a technique introduced by Whitesides [18], has been extensively used to fabricate various types of electrodes [19,20] and electromagnets in polydimethylsiloxane (PDMS).…”

Acoustic impedance-based manipulation of elastic microspheres using travelling surface acoustic waves

“…3,4 The ARF depends on the size, shape, density, and compressibility of the suspended micro-objects, and variations in any of these parameters can be used to distinguish, separate, sort, trap and manipulate microobjects on-demand. 5,6 Most acoustouidics devices, which use bulk acoustic waves (BAWs), [7][8][9][10] Lamb waves (LWs), 11,12 travelling surface acoustic waves (TSAWs) [13][14][15][16][17][18] or standing surface acoustic waves (SSAWs) [19][20][21][22] for the manipulation of microparticles, cells, bacteria, or droplets, depend upon variations in the sizes of the micro-objects. A few studies have reported the use of variations in the intrinsic properties such as the density or compressibility of the micro-objects for their manipulation instead of their sizes.…”