Integration of Ultra-Low Volume Pneumatic Microfluidics with a Three-Dimensional Electrode Network for On-Chip Biochemical Sensing

Abstract

This paper reports a novel miniaturized pseudo reference electrode (RE) design for biasing Ion Sensitive Field Effect Transistors (ISFETs). It eliminates the need for post-CMOS processing and can scale up in numbers with the CMOS scaling. The presented design employs silane-mediated transfer of patterned gold electrode lines onto PDMS microfluidics such that the gold conformally coats the inside of microfluidic channel. Access to this electrode network is made possible by using “through-PDMS-vias” (TPV), which consist of high metal-coated SU-8 pillars manufactured by a novel process that employs a patterned positive resist layer as SU-8 adhesion depressor. When integrated with pneumatic valves, TPV and pseudo-RE network were able to bias 1.5 nanoliters (nL) of isolated electrolyte volumes. We present a detailed characterization of our pseudo-RE design demonstrating ISFET operation and its DC characterization. The stability of pseudo-RE is investigated by measuring open circuit potential (OCP) against a commercial Ag/AgCl reference electrode.

Thermodynamic Characterization of a Highly Transparent Microfluidic Chip with Multiple On-Chip Temperature Control Units

“…Utilizing the physical phenomenon at the microscale, the time and energy efficiency of biochemical reactions could be greatly improved. The excellent compatibility of microfluidics in electromechanical control, medical science and biochemical reactions can also provide a significant possibility for minimizing reaction devices [3][4][5][6][7]. Following advances in techniques and the increase in demand, multiform microfluidic devices have been invented and adopted.…”

“…For the spatially cycled protocol, the temperature at each area is fixed and the reaction solution flows through different temperature zones in turn. The solution could be driven by external pressure in a serpentine channel [7,18], a radial channel [33] or a spiral channel [25]; by integrated pneumatic micro pumps [8], ferro-fluidic plugs [34] or a magnetized ball pressing on a loop channel [35] with a rotating guiding magnet beneath; and by Rayleigh-Bénard convection in a cylindrical cavity [29]. For the temporally cycled protocol, the reaction solution is stationary while the temperature at the entire reaction zone changes over time.…”