Pinch-off droplet generator using microscale gigahertz acoustics.

The generation and dispensing of microdroplets is a vital process in various fields such as biomedicine, medical diagnosis and chemistry. However, most methods still require the structures of nozzles or microchannels to assist droplet generation, which leads to limitations on system flexibility and restrictions on the size range of the generated droplets. In this paper, we propose a nozzle-free acoustic-based method for generating droplets using a gigahertz (GHz) bulk acoustic wave (BAW).

Self-adaptive virtual microchannel for continuous enrichment and separation of nanoparticles.

The transport, enrichment, and purification of nanoparticles are fundamental activities in the fields of biology, chemistry, material science, and medicine. Here, we demonstrate an approach for manipulating nanospecimens in which a virtual channel with a diameter that can be spontaneously self-adjusted from dozens to a few micrometers based on the concentration of samples is formed by acoustic waves and streams that are triggered and stabilized by a gigahertz bulk acoustic resonator and microfluidics, respectively. By combining a specially designed arc-shaped resonator and lateral flow, the in situ enrichment, focusing, displacement, and continuous size-based separation of nanoparticles were achieved, with the ability to capture 30-nm polystyrene nanoparticles and continuously focus 150-nm polystyrene nanoparticles.

100% Single Cell Encapsulation via Acoustofluidic Printing Based on a Gigahertz Acoustic Resonator.

In this study, an acoustofluidic printing system for generation of single-cell droplets based on a gigahertz acoustic resonator was proposed and verified. The working area of the resonator has a typical dimension of 10×10 micrometer which is very suitable for single cell printing. Single cells were encapsulated in picoliter droplets and printed directly to a flat substrate without any significant influence on their viability.

Continuous Enrichment and Separation of Nanoparticles via Acoustic Streaming.

Enrichment and separation of Micro/Nano-scale specimens are fundamental requirements in biomedical researches. In this paper, we demonstrated a simple and efficient microfluidic chip for the continuous enrichment and separation of nanoscale polystyrene particles using the acoustic streaming induced by gigahertz(GHz) bulk acoustic waves(BAW). The bulk acoustic resonator released ultrahigh frequency (2GHz) acoustic waves into the fluid and triggered the acoustic streaming.

An on-demand femtoliter droplet dispensing system based on a gigahertz acoustic resonator.

On-demand droplet dispensing systems are indispensable tools in bioanalytical fields, such as microarray fabrication. Biomaterial solutions can be very limited and expensive, so minimizing the use of solution per spot produced is highly desirable. Here, we proposed a novel droplet dispensing method which utilizes a gigahertz (GHz) acoustic resonator to deposit well-defined droplets on-demand.

Cellphone-Enabled Microwell-Based Microbead Aggregation Assay for Portable Biomarker Detection.

Quantitative biomarker detection methods featured with rapidity, high accuracy, and label-free are demonstrated for the development of point-of-care (POC) technologies or "beside" diagnostics. Microbead aggregation via protein-specific linkage provides an effective approach for selective capture of biomarkers from the samples, and can directly readout the presence and amount of the targets. However, sensors or microfluidic analyzers that can accurately quantify the microbead aggregation are scared.