3D‐Printed Acoustofluidic Devices for Raman Spectroscopy of Cells

Abstract

Acoustofluidics technology can be used to trap live cells (and also micro/nanoparticles) in microenvironments suitable for cell assays. Herein, a cheap and easyto-fabricate device is proposed that works with Raman spectroscopy for biosensing applications. The device comprises a 3D-printed microchamber working as a halfwavelength acoustic resonator. By tuning the resonance frequency with a low voltage (%4 V), cells or particles are aggregated and levitated in seconds by the action of the acoustic radiation force. Based on finite element simulations, the radiation force field produced inside the device is described. In the cellular enrichment (aggregation) process, a metastable honeycomb lattice is formed mostly due to the cell-to-cell attraction caused by the secondary acoustic radiation force. Orderly and metastable levitating aggregates provide an excellent arrangement for Raman spectroscopy to investigate cells individually. Polystyrene particles are used for the device characterization and Raman acquisition process. Biosensing applications are showcased with live murine macrophages J774.A1, which are used in infection assay of leishmaniasis disease. The unique features of the device, e.g., simple fabrication process with cheap materials, simple operation, fast time response, and formation of metastable cellular aggregates; hold a noteworthy potential for applications in life sciences and biotechnology involving cell assays.

Acoustofluidics 24: theory and experimental measurements of acoustic interaction force

“…Recently, an acoustofluidic device was developed to assist in the study of chemical compositions of biological cells using Raman spectroscopy. 53 It operates with a resonance chamber and the contact-free levitation of particles, resulting in measurements with little noise, which are required to conduct accurate scans of a Raman spectrum. In these applications of acoustophoresis, the occurrence of clustering can be attributed to the patterns of acoustic interaction between the objects, which depend on their surrounding conditions too.…”

“…In these applications of acoustophoresis, the occurrence of clustering can be attributed to the patterns of acoustic interaction between the objects, which depend on their surrounding conditions too. The understanding of the interaction force is important to optimise the concentration of such particles and the input power for a stable configuration at the pressure node during scanning, 53 and potentially novel ways of controlling such interactions can be developed for practical applications.…”

“…where q = 1, 2. From B ˜(q) l and D ˜(q) l , the streaming pressure and velocity, and subsequently, stresses are calculated using eqn ( 44) and ( 51)- (53).For object q, the total force in eqn ( 47) can be split into partial forces of radiation and streaming (hydrodynamic) types as…”

Two-photon microscopy of acoustofluidic trapping for highly sensitive cell analysis

“…The visual sample analysis is generally performed using bright-field or confocal microscopy. 10,[15][16][17] Furthermore, Santos et al 18 presented an acoustofluidic device in combination with Raman spectroscopy. However, the Raman method worked only well for particles with a diameter larger than 15 μm in their case because smaller particles were liable to microstreaming effects.…”