Arrangement of Live Human Cells through Acoustic Waves Generated by Piezoelectric Actuators for Tissue Engineering Applications

Abstract

In this paper, the possibility to steer and confine live human cells by means of acoustic waves, such as flexural plate waves (FPWs), generated by piezoelectric actuators applied to non-piezoelectric substrates, has been explored. A device with two lead zirconate titanate (PZT) actuators with an interdigital transducer (IDT) screen-printed on an alumina (Al2O3) substrate has been fabricated and tested. The experimental results show that, by exciting the actuators at their resonant frequencies, FPW modes are generated in the substrate. By exploiting the device, arrangements of cells on lines at frequency-dependent distances have been obtained. To maintain the alignment after switching off the actuator, cells were entrapped in a fibrin clot that was cultured for several days, enabling the formation of cellular patterns.

Exploiting the fundamentals of biological organization for the advancement of biofabrication

“…This approach can lead to the fabrication of soft robotics and the design of dynamic biomaterials [113]. This actuation has also been used to effect cell differentiation by applying tuneable forces, exploiting both the action of molecular motors and the mechanosensing capabilities of cells to direct cell fate (Table 1) [114][115][116]. Materials capable of accessing non-equilibrium states on-demand can be used to biofabricate structures with emergent properties.…”

Piezoelectric MEMS Flexural-Plate-Wave Transducer for Alignment of Microparticles in a Drying Droplet

“…However, both such approaches have the disadvantage of not being fully compliant with biological applications since they can alter cell integrity thus irreversibly damaging the biological tissue [11]. To achieve microassembly ensuring biocompatibility, flowfield approaches exploiting macroscopic viscous flows to direct the assembly of a disordered suspension of particles into ordered structures represent a valid alternative [12], [13]. Among flow-field techniques, acoustophoresis, i.e.…”

“…The acoustic waves are employed to interact with fluids, steer particles dispersed therein, and assemble microstructures at micrometric resolution [24]. A possible limitation in some applications is that, once the flow is removed, the created assembly can possibly revert into disordered particles unless additional substances are added to create clots [13]. To this purpose, an evaporation-based assembly process employing droplets deposited on surfaces can be an effective solution [25].…”

Cell Alignment in Aqueous Solution Employing a Flexural Plate Wave Piezoelectric MEMS Transducer

“…Acoustic waves are then employed as a coupling mean to exchange energy and to induce forces into the liquid where cells are typically dispersed [16]. Specifically, in a standing wave field the acoustic radiation force (ARF) drives the particles dispersed in liquid into acoustic pressure nodes, thus allowing their manipulation and alignment [17,18]. Bulk acoustic waves (BAW) [19], surface acoustic waves (SAW) [20], and flexural plate waves (FPW) [21], are typical acoustic modes exploited in piezoelectric transducers.…”