Hybrid Microfluidic Platform for Multifactorial Analysis Based on Electrical Impedance, Refractometry, Optical Absorption and Fluorescence

This paper describes the development of a novel microfluidic platform for multifactorial analysis integrating four label-free detection methods: electrical impedance, refractometry, optical absorption and fluorescence. We present the rationale for the design and the details of the microfabrication of this multifactorial hybrid microfluidic chip. The structure of the platform consists of a three-dimensionally patterned polydimethylsiloxane top part attached to a bottom SU-8 epoxy-based negative photoresist part, where microelectrodes and optical fibers are incorporated to enable impedance and optical analysis. As a proof of concept, the chip functions have been tested and explored, enabling a diversity of applications: (i) impedance-based identification of the size of micro beads, as well as counting and distinguishing of erythrocytes by their volume or membrane properties; (ii) simultaneous determination of the refractive index and optical absorption properties of solutions; and (iii) fluorescence-based bead counting.
Funding Agencies|FEDER funds through the COMPETE 2020 Programme; National Funds through Fundacao para a Ciencia e a Tecnologia (FCT) [UID/CTM/50025/2013, PTDC/SAU-BEB/102247/2008]; project "Project" NanoSTIMA: Macro-to-Nano Human Sensing: Towards Integrated Multimodal Health Monitoring and Analytics - North Portugal Regional Operational Programme [NORTE-01-0145-FEDER-000016]; European Regional Development Fund (ERDF); North Portugal Regional Operational Program under the National Strategic Reference Framework (NSRF), through the European Regional Development Fund (ERDF) [NORTE-07-0124-FEDER-000058]; national funds, through the Portuguese funding agency, FCT