Solution-gated graphene field effect transistors integrated in microfluidic systems and used for flow velocity detection.
Solution-gated graphene field effect transistors (SGGT) were integrated in microfluidic systems. The transfer characteristics of a SGGT with an Ag/AgCl gate electrode shifted horizontally with the change of the ionic concentration of KCl solution in the microchannel and the relationship can be fitted with the Nernst equation, which was attributed to the change of the potential drop at the Ag/AgCl electrode. Therefore the gate electrode is one important factor for the ion sensitive property of the SGGT. Then SGGTs were used as flow velocity sensors, which were based on measuring the streaming potentials in microfluidic channels. A linear relationship between the shift of the transfer curve of the SGGT and the flow velocity was obtained, indicating that the SGGT is a promising transducer for measuring flow velocity in a microchip. Since the streaming potential is influenced by the three physical quantities, including the flow velocity, the ionic strength of the fluid and the zeta potential of the substrate, the device can be used for sensing any one of the three quantities when the other two were known. It is noteworthy that SGGTs have been used for various types of chemical and biological sensors. Array of the devices integrated in multichannel microchips are expected to find many important applications in the lab-on-a-chip systems in the future.
Department of Applied Physics and Materials Research Centre, The Hong Kong Polytechnic University, Hong Kong, China.
Rong Xiang
RX
He
Peng
P
Lin
Zhi Ke
ZK
Liu
Hong Wei
HW
Zhu
Xing Zhong
XZ
Zhao
Helen L W
HL
Chan
Feng
F
Yan
D004867:Equipment Design; D019544:Equipment Failure Analysis; D006108:Graphite / Q000737:chemistry*; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation*; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D036103:Nanotechnology / Q000295:instrumentation*; D012212:Rheology / Q000295:instrumentation*; D012996:Solutions / Q000737:chemistry; D018511:Systems Integration; D014173:Transistors, Electronic
D012996:Solutions; D006108:Graphite