Chemoreceptive Neuron MOS Research Articles

Non-Faradaic Electrochemical Detection of Exocytosis from Mast and Chromaffin Cells Using Floating-Gate MOS Transistors.

We present non-faradaic electrochemical recordings of exocytosis from populations of mast and chromaffin cells using chemoreceptive neuron MOS (CνMOS) transistors. In comparison to previous cell-FET-biosensors, the CνMOS features control (CG), sensing (SG) and floating gates (FG), allows the quiescent point to be independently controlled, is CMOS compatible and physically isolates the transistor channel from the electrolyte for stable long-term recordings. We measured exocytosis from RBL-2H3 mast cells sensitized by IgE (bound to high-affinity surface receptors FcεRI) and stimulated using the antigen DNP-BSA. Quasi-static I-V measurements reflected a slow shift in surface potential () which was dependent on extracellular calcium ([Ca]o) and buffer strength, which suggests sensitivity to protons released during exocytosis. Fluorescent imaging of dextran-labeled vesicle release showed evidence of a similar time course, while un-sensitized cells showed no response to stimulation. Transient recordings revealed fluctuations with a rapid rise and slow decay. Chromaffin cells stimulated with high KCl showed both slow shifts and extracellular action potentials exhibiting biphasic and inverted capacitive waveforms, indicative of varying ion-channel distributions across the cell-transistor junction. Our approach presents a facile method to simultaneously monitor exocytosis and ion channel activity with high temporal sensitivity without the need for redox chemistry.

Non-Faradaic electrochemical detection of protein interactions by integrated neuromorphic CMOS sensors

Electronic detection of the binding event between biotinylated bovine serum albumen (BSA) and streptavidin is demonstrated with the chemoreceptive neuron MOS (CνMOS) device. Differing from the ion-sensitive field-effect transistors (ISFET), CνMOS, with the potential of the extended floating gate determined by both the sensing and control gates in a neuromorphic style, can provide protein detection without requiring analyte reference electrodes. In comparison with the microelectrode arrays, measurements are gathered through purely capacitive, non-Faradaic interactions across insulating interfaces. By using a (3-glycidoxypropyl)trimethoxysilane (3-GPS) self-assembled monolayer (SAM) as a simple covalent link for attaching proteins to a silicon dioxide sensing surface, a fully integrated, electrochemical detection platform is realized for protein interactions through monotone large-signal measurements or small-signal impedance spectroscopy. Calibration curves were created to coordinate the sensor response with ellipsometric measurements taken on witness samples. By monitoring the film thickness of streptavidin capture, a sensitivity of 25ng/cm2 or 2Å of film thickness was demonstrated. With an improved noise floor the sensor can detect down to 2ng/(cm2mV) based on the calibration curve. AC measurements are shown to significantly reduce long-term sensor drift. Finally, a noise analysis of electrochemical data indicates 1/fα behavior with a noise floor beginning at approximately 1Hz.

Time-Resolved Charge Transport Sensing by Chemoreceptive Neuron MOS Transistors $({\rm C}\nu{\rm MOS})$ With Microfluidic Channels

Charge-based sensing in chemoreceptive neuron MOS (CvMOS)transistors with extended floating-gate structures has brought forth features that are beneficial to the system integration of chemical sensing. This paper presents the results of integrating CvMOS with wafer-bonding microfluidic channels for reliable time-resolved ion and molecular transport sensing, which can find potential applications in a microanalysis system.

Thermal and Pressure Sensing by Chemoreceptive Neuron MOS Transistors (CνMOS) with PVDF Coating

ABSTRACTThis paper reports the integration of poled 10μm +/- 1μm P(VDF-TrFe) copolymer thin films with an adapted non-volatile, foundry-compatible CMOS structure (CνMOS) for the potential purposes of in-vivo piezoelectric and pyroelectric sensing. This structure allows for direct, reliable interaction between the sensing transducer and the highly sensitive MOSET gate stack without the need for an external reference electrode or chopper, as other designs may require.

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

An integration of chemical sensors and electrowetting actuators based on the chemoreceptive neuron MOS (CνMOS) transistors has brought forth a novel system-on-chip approach to the microfluidic system. The extended floating-gate structure of the CνMOS 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.

Charge-based chemical sensors: a neuromorphic approach with chemoreceptive neuron MOS (C/sub V/MOS) transistors

A novel chemoreceptive neuron MOS (C/spl nu/MOS) transistor with an extended floating-gate structure has been designed with several individual features that significantly facilitate system integration of chemical sensing. We have fabricated C/spl nu/MOS transistors with generic molecular receptive areas and have characterized them with various fluids. We use an insulating polymer layer to provide physical and electrical isolation for sample fluid delivery. Experimental results from these devices have demonstrated both high sensitivity via current differentiation and large dynamic range from threshold voltage shifts in sensing both polar and electrolytic liquids. We have established electrochemical models for both steady-state and transient analyses. Our preliminary measurement results have confirmed the basic design and operations of these devices, which show potential for developing silicon olfactory and gustatory units that are fully compatible with current CMOS technology.