EMBL Conference, Microfluidics 2014
23-25 July 2014, Heidelberg, Germany
Microfluidic chemical transistor based on volume phase transition polymer
Because of the similarity between integrating multiple fluidic functions and electronic functions in a signgle device, microfluidics has often been compared with microelectronics. Moreover, most of the microfluidic fabrication techniques rely on photolithography and associated technologies that had been successful in microelectronics. Compared to the successes of microelectronics in the past 50 years, microfluidics is still at an early stage attempting the transition from academic research to an important commercial technology. Considering the significant role of the transistor in microelectronics, we believe that the absence of transistor-like components in microfluidics is a key reason for not producing the expected revolution in its applications.
Volume phase transition polymers change their volume significantly in response to small alterations of the chemical and themodynamic characteristics of liquids, like temperature, solute concentration or pH value. By utilising stimuli-sensitive polymers, we present a microfluidic chemical transistor which is based on a chamber filled with a stimuli-sensitive polymer. Its resistance depends on the volume ratio between the polymer and the whole chamber and hence on the concentration of alcohol dissolved in water and the temperature. This concentration-controlled microfluidic transistor shows strong similarities to the voltage-controlled microelectronic MOSFET and is characterised by its output and trasfer characteristic curves. Most importantly, the microfluidic transistor can control the flow rate in a completely self-controlled manner, i.e. without any external control unit or power supply. As a result, it not only provides a novel method for manipulating fluids, but also makes it possible to realise self-controlled microfluidic chips based on chemical transistor.