skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


  • NSF Public Access
  • Search Results
  • Three-dimensional numerical simulation and experimental investigation of boundary-driven streaming in surface acoustic wave microfluidics
Title: Three-dimensional numerical simulation and experimental investigation of boundary-driven streaming in surface acoustic wave microfluidics
Acoustic streaming has been widely used in microfluidics to manipulate various micro−/nano-objects. In this work, acoustic streaming activated by interdigital transducers (IDT) immersed in highly viscous oil is studied numerically and experimentally. In particular, we developed a modeling strategy termed the “slip velocity method” that enables a 3D simulation of surface acoustic wave microfluidics in a large domain (4 × 4 × 2 mm 3 ) and at a high frequency (23.9 MHz). The experimental and numerical results both show that on top of the oil, all the acoustic streamlines converge at two horizontal stagnation points above the two symmetric sides of the IDT. At these two stagnation points, water droplets floating on the oil can be trapped. Based on these characteristics of the acoustic streaming field, we designed a surface acoustic wave microfluidic device with an integrated IDT array fabricated on a 128° YX LiNbO 3 substrate to perform programmable, contactless droplet manipulation. By activating IDTs accordingly, the water droplets on the oil can be moved to the corresponding traps. With its excellent capability for manipulating droplets in a highly programmable, controllable manner, our surface acoustic wave microfluidic devices are valuable for on-chip contactless sample handling and chemical reactions.  more » « less
Award ID(s):
1807601
PAR ID:
10112323
Author(s) / Creator(s):
; ; ; ; ; ; ; ; ;
Date Published:
Journal Name:
Lab on a Chip
Volume:
18
Issue:
23
ISSN:
1473-0197
Page Range / eLocation ID:
3645 to 3654
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; ; ; ; ; ; ; ; ; et al (, Lab on a Chip)
    Contact-free manipulation of small objects ( e.g. , cells, tissues, and droplets) using acoustic waves eliminates physical contact with structures and undesired surface adsorption. Pioneering acoustic-based, contact-free manipulation techniques ( e.g. , acoustic levitation) enable programmable manipulation but are limited by evaporation, bulky transducers, and inefficient acoustic coupling in air. Herein, we report an acoustofluidic mechanism for the contactless manipulation of small objects on water. A hollow-square-shaped interdigital transducer (IDT) is fabricated on lithium niobate (LiNbO 3 ), immersed in water and used as a sound source to generate acoustic waves and as a micropump to pump fluid in the ± x and ± y orthogonal directions. As a result, objects which float adjacent to the excited IDT can be pushed unidirectionally (horizontally) in ± x and ± y following the directed acoustic wave propagation. A fluidic processor was developed by patterning IDT units in a 6-by-6 array. We demonstrate contactless, programmable manipulation on water of oil droplets and zebrafish larvae. This acoustofluidic-based manipulation opens avenues for the contactless, programmable processing of materials and small biosamples. 
    more » « less
  2. ; ; ; ; ; ; ; ; ; ; et al (, Microsystems & Nanoengineering)
    Abstract The addition of surface acoustic wave (SAW) technologies to microfluidics has greatly advanced lab-on-a-chip applications due to their unique and powerful attributes, including high-precision manipulation, versatility, integrability, biocompatibility, contactless nature, and rapid actuation. However, the development of SAW microfluidic devices is limited by complex and time-consuming micro/nanofabrication techniques and access to cleanroom facilities for multistep photolithography and vacuum-based processing. To simplify the fabrication of SAW microfluidic devices with customizable dimensions and functions, we utilized the additive manufacturing technique of aerosol jet printing. We successfully fabricated customized SAW microfluidic devices of varying materials, including silver nanowires, graphene, and poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS). To characterize and compare the acoustic actuation performance of these aerosol jet printed SAW microfluidic devices with their cleanroom-fabricated counterparts, the wave displacements and resonant frequencies of the different fabricated devices were directly measured through scanning laser Doppler vibrometry. Finally, to exhibit the capability of the aerosol jet printed devices for lab-on-a-chip applications, we successfully conducted acoustic streaming and particle concentration experiments. Overall, we demonstrated a novel solution-based, direct-write, single-step, cleanroom-free additive manufacturing technique to rapidly develop SAW microfluidic devices that shows viability for applications in the fields of biology, chemistry, engineering, and medicine. 
    more » « less
  3. ; ; ; ; ; ; ; ; ; ; et al (, Advanced Materials Technologies)
    Abstract Tweezers based on optical, electric, magnetic, and acoustic fields have shown great potential for contactless object manipulation. However, current tweezers designed for manipulating millimeter‐sized objects such as droplets, particles, and small animals exhibit limitations in translation resolution, range, and path complexity. Here, a novel acoustic vortex tweezers system is introduced, which leverages a unique airborne acoustic vortex end effector integrated with a three‐degree‐of‐freedom (DoF) linear motion stage, for enabling contactless, multi‐mode, programmable manipulation of millimeter‐sized objects. The acoustic vortex end effector utilizes a cascaded circular acoustic array, which is portable and battery‐powered, to generate an acoustic vortex with a ring‐shaped energy pattern. The vortex applies acoustic radiation forces to trap and spin an object at its center, simultaneously protecting this object by repelling other materials away with its high‐energy ring. Moreover, The vortex tweezers system facilitates contactless, multi‐mode, programmable object surfing, as demonstrated in experiments involving trapping, repelling, and spinning particles, translating particles along complex paths, guiding particles around barriers, translating and rotating droplets containing zebrafish larvae, and merging droplets. With these capabilities, It is anticipated that the tweezers system will become a valuable tool for the automated, contactless handling of droplets, particles, and bio‐samples in biomedical and biochemical research. 
    more » « less
  4. ; ; ; ; ; (, Lab on a Chip)
    Combining electrochemistry with microfluidics is attractive for a wide array of applications including multiplexing, automation, and high-throughput screening. Electrochemical instrumentation also has the advantage of being low-cost and can enable high analyte sensitivity. For many electrochemical microfluidic applications, carbon electrodes are more desirable than noble metals because they are resistant to fouling, have high activity, and large electrochemical solvent windows. At present, fabrication of electrochemical microfluidic devices bearing integrated carbon electrodes remains a challenge. Here, a new system for integrating polycaprolactone (PCL) and carbon composite electrodes into microfluidics is presented. The PCL : carbon composites have excellent electrochemical activity towards a wide range of analytes as well as high electrical conductivity (∼1000 S m −1 ). The new system utilizes a laser cutter for fast, simple fabrication of microfluidics using PCL as a bonding layer. As a proof-of-concept application, oil-in-water and water-in-oil droplets are electrochemically analysed. Small-scale electrochemical organic synthesis for TEMPO mediated alcohol oxidation is also demonstrated. 
    more » « less
  5. ; ; (, International polymer processing)
    This work focuses on fabrication of multi-hollow polyimide gel and aerogel particles from a surfactant-free oil-in-oil emulsion system using a microfluidic droplet generator operating under dripping mode. The multi-hollow gel and aerogel particles have strong potential in thermal insulation. Under jetting and tip-streaming regime of microfluidic flows, droplets are generated with no occluded liquid phase. The present study investigates a means of designing polyimide gel particles with plurality of internal liquid droplets by strategically manipulating the flow rates of the continuous and dispersed phase liquids through the microfluidic droplet generator. The multi-hollow polyimide aerogel particles obtained after supercritical drying of the gel particles present mesopores, high BET surface area, and excellent prospect for thermal insulation. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email