Towards the development of a fully integrated polymeric microfluidic platform for environment analysis

In this paper we report the development and assessment of a biomimetic pump based on soft polymeric actuators, i.e. polyurethane tubes (950 μm internal diameter) with polypyrrole, which expands and contracts during redox cycling and provides the driving force for liquid movement. This pump can be integrated in the microfluidic channels, functioning in a similar manner similar to blood vessels. In principle, these biomimetic pumps and low power detectors could be integrated into a fully functional and totally integrated microanalytical platform. It was also low power (of the order of 100 mJ/μL to obtain a flow rate of 0.08 μL/s), operating using voltages of up to ±1 V, and requiring currents of less than 100 mA. The flow rates achieved are comparable to miniaturised commercial pumps, with the benefit of considerably reduced power consumption (a conventional miniaturised peristaltic pump consumes ca. 3.6 J/μL to obtain the same flow rates as the pump integrated in this system). The microchip was constructed using polydimethylsiloxane (PDMS) and designed to provide the appropriate mixing of reagents in order to obtain optimum response from the sensors. The chip incorporated an optical detection system constructed using miniaturised light emitting diodes (LED) for both the light source and the detector. This low-cost and low-power detector was surprisingly sensitive due to its integrating mode of operation, and exhibited very low limits of detection. In the present system, conventional LEDs were employed as proof of concept. However, surface mount LEDs will be employed which will allow for a much more compact and compatible format for use in microfluidic manifolds than conventional LEDs. The low-power biomimetic pump, and the low power detector system were assessed as components that could be integrated into a futuristic integrated microanalytical platform.