A Novel Compact Lab-on-a-Chip Nanosensor for In-Channel Liquid Viscosity Detection

J. Zhao, J. Xu, W. Xue
Washington State University Vancouver, US

Keywords: lab-on-a-chip, SWNT, nanosensor, viscosity


Real-time monitoring of liquid’s viscosity has significant impacts on many areas such as medicine, biology and petrochemistry. However, most existing sensors have complicated fabrication and testing processes and are not truly compatible with fluidic systems for on-site viscosity detection. Here we report a novel lab-on-a-chip device with integrated nanosensors for viscosity detection. The device enables real-time, in-channel detection of the viscosity of flowing fluids. Single-walled carbon nanotubes (SWNTs) aligned across two electrodes in a sealed microchannel are used as nanoscale sensors. The deposition of SWNTs is achieved through in-channel AC electrical field alignment using dielectrophoresis. In our experiment continuous fluids with a constant flow rate of 0.1 ml/min are injected into the channel with a high-precision syringe pump. The sensor resistance increases when the fluid viscosity rises. The lowest resistance is measured as 8,000 Ω in water and the highest value is 10,500 Ω in a 50% glycerol solution. We believe that the resistance change is caused by the shear forces applied on the SWNTs. The knowledge obtained from this research can enable the development of novel lab-on-a-chip sensors for applications in medical areas such as blood testing and disease diagnostics.