Department of Mechanical Engineering and Materials Science, Washington University in St. Louis, St. Louis, Missouri 63130, USA.
Lab Chip. 2021 Jun 29;21(13):2534-2543. doi: 10.1039/d1lc00257k.
Controlled trapping of cells and microorganisms using substrate acoustic waves (SAWs; conventionally termed surface acoustic waves) has proven useful in numerous biological and biomedical applications owing to the label- and contact-free nature of acoustic confinement. However, excessive heating due to vibration damping and other system losses potentially compromises the biocompatibility of the SAW technique. Herein, we investigate the thermal biocompatibility of polydimethylsiloxane (PDMS)-based SAW and glass-based SAW [that supports a bulk acoustic wave (BAW) in the fluid domain] devices operating at different frequencies and applied voltages. First, we use infrared thermography to produce heat maps of regions of interest (ROI) within the aperture of the SAW transducers for PDMS- and glass-based devices. Motile Chlamydomonas reinhardtii algae cells are then used to test the trapping performance and biocompatibility of these devices. At low input power, the PDMS-based SAW system cannot generate a large enough acoustic trapping force to hold swimming C. reinhardtii cells. At high input power, the temperature of this device rises rapidly, damaging (and possibly killing) the cells. The glass-based SAW/BAW hybrid system, on the other hand, can not only trap swimming C. reinhardtii at low input power, but also exhibits better thermal biocompatibility than the PDMS-based SAW system at high input power. Thus, a glass-based SAW/BAW device creates strong acoustic trapping forces in a biocompatible environment, providing a new solution to safely trap active microswimmers for research involving motile cells and microorganisms.
利用基底声波（通常称为表面声波）对细胞和微生物进行受控捕获在许多生物和生物医学应用中已经被证明是有用的，这是因为声学限制具有无标记和非接触的特性。然而，由于振动阻尼和其他系统损耗导致的过热可能会损害 SAW 技术的生物相容性。在这里，我们研究了基于聚二甲基硅氧烷（PDMS）的 SAW 和基于玻璃的 SAW（在流体域中支持体声波（BAW））器件在不同频率和施加电压下的热生物相容性。首先，我们使用红外热成像技术生成 SAW 换能器孔径内感兴趣区域（ROI）的热图，用于 PDMS 和玻璃基器件。然后，使用运动性莱茵衣藻细胞来测试这些器件的捕获性能和生物相容性。在低输入功率下，基于 PDMS 的 SAW 系统无法产生足够大的声捕获力来固定游动的 C. reinhardtii 细胞。在高输入功率下，该设备的温度迅速升高，从而损坏（可能杀死）细胞。另一方面，基于玻璃的 SAW/BAW 混合系统不仅可以在低输入功率下捕获游动的 C. reinhardtii，而且在高输入功率下比基于 PDMS 的 SAW 系统具有更好的热生物相容性。因此，基于玻璃的 SAW/BAW 器件在生物相容的环境中产生强大的声捕获力，为安全捕获用于涉及游动细胞和微生物的研究的活性微泳者提供了新的解决方案。
