Authors: P. Truman, P. Uhlmann and M. Stamm
Affilation: Institute of Polymer Research, Germany
Pages: 320 - 323
Keywords: fluid transport, flow, electrochemical sensing, micro fluidic devices, nano fluidic devices
Observation and monitoring liquid transport and transport in liquids is a major task for lab on a chip applications and research. We use novel thin film FET devices based on silicon-on-insulator (SOI) substrates as planar sensors for the detection of liquid transport in capillaries to overcome the drawbacks of optical flow observation techniques the same time providing chemical composition analysis capabilities of ISFET technologies. Based on a newly developed theoretical model for Field-Effect liquid movement detection we demonstrate fundamental applications like the detection of capillary filling speed and level. To proof compatibility with ISFET technologies we demonstrate chemical composition analysis capabilities like pH-detection with a resolution of ΔpH = 0.2 and sensitivity to ionic strength by recording device signal as a function of KCL concentration with a resolution of 0.3M. Furthermore we show how the sensitivity of the devices can be tuned by an additional backgate as a unique feature provided by the use of silicon-on-insulator substrates. Finally we will discuss extensions of our theoretical model systems with respect to probing boundary conditions by a differential speed analysis approach, comment on the relation between the direction of liquid movement and electrical current and estimate the limitations of this approach.