Lab on Chip Microsystems
1. Single Cell Engineering
Objective: Develop high throughput microfluidic platforms for single cell engineering, which involves isolation (e.g. trapping, sorting), manipulation (e.g. lysing, electroporation) and sensing.
Approach: Compared to the conventional approach of studying the culture of cells that measure average cell response and obscure crucial differences between them, single cell studies allow one to catalogue individual cell behavior and capture cellular heterogeneity. We have built a lab-on-chip device for high-throughput trapping and lysis of single cells with in-situ impedance monitoring in an all-electronic approach. We have even also made single CMOS platforms for discriminating single cells based on their electrophysiological response to AC electric fields.
1. All electronic approach for high-throughput single cell trapping and lysis with electrical impedance monitoring, Biosensors and Bioelectronics, vol. 54, no.4, pp. 462-467, April 2014
2. Utilization of graphene electrode in transparent microwell arrays for high throughput cell trapping and lysis, Biosensors and Bioelectronics, vol. 61, no. 11, pp. 625-630, 2014.
3. Dielectrophoretic lab-on-CMOS platform for trapping and manipulation of cells, Biomedical microdevices, 18(1), p.6 2016.
2. Point of Care Diagnostics
Objective: To develop diagnostic tools based on optical or chemiresistive sensor arrays to detect biomarkers of disease or pollution using consumer devices (smartphone, flatbed scanner) for readout.
Approach: We have leveraged our low cost fabrication paradigm using screen printing on paper or textile substrates to realize colorimetric sensor arrays (aka optical nose) for cross-reactive sensing of ambient or dissolved gases. Color readout was achieved using smartphone or flatbed scanner. We applied this to saliva diagnostic for detection of H.pylori infection, which is an early warning sign for stomach ulcers and stomach cancer. Our paper-based optical nose could measure ppb level of CO2 and ammonia, byproducts of H.pylori in our breath/saliva. We also implemented paper-based optical nose to monitor volatile organic compounds (VOC) emanating from food as signs of food freshness and to detect spoilage objectively, suitable for an entire farm-to-table supply chain. As an alternate to an optical scheme, we have also screen-printed nanomaterial inks (graphene, CNT, metal oxide, polypyrrole etc.) to make an electronic nose, which measures unique chemiresistive response of these nanomaterials to target gas/vapor. We have also assembled these nanomaterial inks directly on CMOS chip, using dielectrophoresis (DEP) for a single CMOS chip for VOC detection.
- Microfluidic optoelectronic sensor for salivary diagnostics of stomach cancer, Biosensors and Bioelectronics, vol. 67, pp. 465-471, May 2015
- Combined optical and electronic paper-nose for detection of volatile gases, Analytica Chimica Acta, vol. 1034, pp. 128-136, 2018.
- DNA-decorated carbon nanotubes based chemical sensors integrated onto complementary metal oxide semiconductor circuitry”, Nanotechnology, vol. 21, pp. 095504, 2010.
- Design, implementation, and field-testing of a portable fluorescence-based vapor sensor. Analytical chemistry, 81(13), 5281-5290, 2009.
- Low cost smart phone diagnostics for food using paper-based colorimetric sensor arrays. Food control, 82, 227-232, 2017.