Integration of chemical sensing and electrowetting actuation on chemoreceptive neuron MOS (CvMOS) transistors

An integration of chemical sensors and electrowetting actuators based on the chemoreceptive neuron MOS (CnuMOS) transistors has brought forth a novel system-on-chip approach to the microfluidic system. The extended floating-gate structure of the CnuMOS transistors enables monolithic sensing and actuating schemes. The sensors with generic chemical receptive areas have been characterized with various fluids. and have demonstrated a high sensitivity from the current differentiation and a large dynamic range from threshold-voltage shifts in sensing polar and electrolytic liquids. The actuators have illustrated valve functions based on contact-angle modification by nonvolatile charge injection into the channel wall. Electrochemical models for sensing and actuation have been established, respectively. A transparent polymer microfluidic layer is adapted to provide physical and electrical isolation for sample fluid delivery and to offer convenient observation. The preliminary experimental results have verified the designs and operations of these devices and shown the potential in developing the dual-function devices with low power consumption and full compatibility with the conventional CMOS technology. (C) 2003 Elsevier B.V. All rights reserved.