The ability to precisely manipulate micron-sized particles and biological cells enables a wide range of biological applications. We are exploring the use of surface acoustic waves (SAWs) in microfluidics for various particle and cell manipulation. A key advantage of this technology is its attractive biocompatibility. Cells exposed to mild acoustic fields retain their viability/morphology over periods of exposure from minutes to hours. Acoustic waves can easily propagate through solids and fluids, which readily enable non-contact cell manipulation. Our research aims to 1) explore unique physical phenomena associated with interactions between acoustic waves and fluids/particles; 2) apply SAW-based microscale manipulation technique for practical biological applications, such as flow cytometry (via cell positioning), cell-cell interaction study (via cell patterning) and rare cell concentration (via cell sorting).
Single cell analysis is needed for characterizing heterogeneous populations, which has broad applications in biological research and disease diagnosis. Current single cell analysis is accomplished using flow cytometry in a laboratory setting, which is typically based on the identification of specific cell biomarkers (e.g. protein antigens on the cell surface). Although effective and highly specific, its bulky size, high cost and need of highly trained technicians limits its use exclusively in centralized biological laboratories. We are developing both on-chip imaging and electrical sensing techniques for single cell analysis in miniaturized microfluidic systems. These portable systems would bring single cell analysis capability to field-deployable applications.
Due to the small size and unique properties of nanomaterials, their interactions with biological molecules have been found as an effective and simple approach for biosensing. We are exploring the use of nanomaterials as “nanoquenchers” in microfluidic devices to develop various fluorometric biosensors. We have developed molybdenum disulfide (MoS2) and graphene oxide (GO) nanosheets based fluorometric biosensors that have the ability to detect ∼fmol DNA in a visible manner within few minutes through the microfluidic assay. We are also pushing the sensing limit to detect single-base mismatch for genotyping single nucleotide polymorphisms (SNPs).