Session: 16-01-01: Poster Session: NSF-Funded Research (Grad & Undergrad)

Paper Number: 100061

100061 - Standing Surface Acoustic Wave Enable Alignment of Nanomaterials in Hydrogel 

Standing Surface Acoustic Wave Enable Alignment of Nanomaterials in Hydrogel

Hydrogels have reportedly been used as novel materials in the applications of soft robotics, biosensing, and tissue engineering. Due to their superior water-absorption capability and extended service life, synthetic hydrogels progressively supplanted natural varieties. Acoustic assisted particle patterning has been developed as an effective way of manipulating nanoparticles.

In this paper, we investigated a method of nanoparticle manipulation based on surface acoustic waves (SAWs). The SAW device is consisted of a piezoelectric substrate and a pair of interdigital transducers (IDTs) which are deposited on the piezoelectric substrate through electron-beam evaporation. Fabricated straight IDTs are capable of generating SAWs with parallel straight wavefronts. By using the paired straight IDTs, a standing SAWs field can be generated in the area between the two IDTs. As the liquid medium, we employ pre-polymerized hydrogel. The utilized nanoparticles will be manipulated by the applied force from the standing SAWs in the pre-polymerized hydrogel. To show the varied effects of the acoustic field in the liquid layer and the accompanied electric field on the piezoelectric substrate, both nanoparticles of low conductivity and high conductivity are involved. After the pre-polymerized hydrogel with the patterned nanoparticles has been polymerized, an acoustic-assisted biocompatible material is fabricated.

The generated acoustic field and accompanied electric field in the SAWs device is modeled by using a finite element simulation. The simulated results under the steady-state in the frequency domain are represented. The results of simulation in the liquid domain represent the distribution of generated acoustic pressures, which indicate the direction of particle entrapment for the particles with low conductivity. The potential field in the solid domain represents the distribution of the accompanied electric field, which indicates the pattern of the particles with high conductivity. The different mechanisms of the acoustic field and the potential field indicate the different patterns of particles with low conductivity and particles with high conductivity.

A proof-of-concept experiment is performed to verify the SAW-based device with the finite element modeling results in this study as well. The recorded results from the optical microscope show that the alignment of the particles with low conductivity is different from the particles with high conductivity. The particles with low conductivity are aligned by the acoustic field as equally spaced paralleled lines. The particles with high conductivity are patterned by the electric field into the short lines periodically with equal spacing.

The aligned and patterned results are matched to the finite element simulation results. We anticipate that the findings of this work could lead to an effective method for nanomaterials manipulating and contributing to bio-fabrication.

Presenting Author: Jiali Li Mississippi State University

Presenting Author Biography: Jiali Li<br/>Aerospace Engineering Ph.D. Student (2020-Present)<br/><br/>Department of Aerospace Engineering, Mississippi State University <br/><br/>Email: jl3285@msstate.edu <br/><br/>Background <br/><br/>MSU Graduate Research Assistant, 2020-Present <br/><br/>Harco Manufacturing Group, 2018-2020<br/><br/>M.S., University of Dayton, 2015-2018<br/><br/>B.S., China University of Petroleum, 2011-2015

Authors: