J.H. Huang

High temporal resolution electrochemical biosensor using nitrogen-incorporated nanodiamond ultra-microelectrode array

Biosensors for detecting/measuring/monitoring the concentration of neurotransmitters that vary at sub-second time-scale can be achieved by using an electrode with high temporal resolution and fast electron transfer kinetics. Neurotransmitters, such as dopamine, undergo rapid fluctuations in concentrations occurring at a sub-second time scale. Real-time monitoring and measurement of these concentrationn changes, in-vivo or in-vitro, requires the use of ultra-microelectrode array (UMEA). This work reports on the development of a reliable UMEA electrochemical biosensor which can be used to identify, quantify, and monitor essential bio-analytes such as dopamine (DA), ascorbic acid (AA) and uric acid (UA) by using CVD nitrogen-incorporated nanodiamond UMEA without the need of electrode surface functionalization or modifications, making real-time detection possible. The application of fast-scan voltammetry (FSCV) for detecting dopamine and interfering bio-chemicals, including ascorbic acid and uric acid in 0.1M PBS (pH 7.4) by the UMEA has been realized. The detailed experiential method for the sensor array fabrication, and the UMEA sensitivity, selectivity, and detection limit for the detection of bio-analytes will be discussed.

Design and fabrication of single-chip carbon nanotubes vacuum field emission differential amplifier

In this paper, the design and fabrication of a single chip carbon nanotubes (CNT) vacuum field emission differential amplifier (VFE diff-amp) is presented for the first time. A dual-mask microfabrication process is employed to achieve the single-chip VFE diff-amp that integrates two identical vacuum field emission transistors with built-in split gates and integrated anodes.

Vacuum field emission integrated differential amplifier

This paper reports the development of an integrated vacuum field emission transistor differential amplifier (diff-amp) utilizing nanodiamond emitters. The device was fabricated by a dual-mask self-aligned mold transfer technique using standard silicon microfabrication technique in conjunction with chemical vapor deposited nanodiamond. The emission current of the transistor pair was validated by the Fowler-Nordheim equation. Well-matched field emission transistor characteristics and large common-mode rejection ratio of 55 dB were obtained, suggesting the capability of the device to reject common-mode noises and to amplify the information contained in differential signals.

Nanodiamond vacuum field emission integrated devices

The superb material properties of nanocrystalline diamond (nanodiamond) materials coupled with practical chemical vapor deposition (CVD) processing of deposited nitrogen-incorporated nanodiamond on variety of substrates, have promoted further interest in the use of these diamond-derived materials as electron field emitters. Experimentally, nanodiamond emitters have been observed to emit electrons at relatively low electric fields and generate useful current densities. In this work, recent development in nanodiamond vacuum field emission integrated electronic devices, viz., the nanodiamond triodes, transistors and integrated differential amplifiers are examined. The material properties, device structure and fabrication process, and the electrical performance of these devices are presented.

Nanodiamond vacuum field emission microtriode

Vacuum field emission (VFE) microtriodes utilizing nanodiamond emitters, integrated with a self-aligned silicon gate and an anode and fabricated by the mold-transfer patterning technique on a silicon-on-insulator (SOI) substrate, have been developed. The nanodiamond VFE microtriodes were fabricated by an integrated circuit-compatible microfabrication process in conjunction with chemical vapor deposition of nanodiamond into the inverted-pyramidal molds micropatterned on the SOI substrate, which provides precision controlled emitter-gate alignment and spacing. The devices exhibited triode characteristics showing anode field induced electron emission with gate controlled emission current modulation at low operating voltages, agreeing with its electron emission transport model. A high current density of 150 mA/cm2 is achievable from the device with the anode-emitter spacing of 4 μm at low operating voltages of Va = 48.5 V and Vg = 5 V. The ac characteristics of the microtriodes for signal amplification were e...

Nanodiamond vacuum field emission triode signal amplifier

This paper presents the triode behavior of a gated nanodiamond vacuum field emitter array and its application in signal amplification. The triode feature is demonstrated with the observation of gate modulation on the emission current induced by the anode field. The emission characteristics are studied by considering the resultant electrical field on emitters, confirming the gate modulation effect. The voltage gain is examined, showing a reasonable value of 6.7 at the operating current of 50 μA. Higher gain is attainable at elevated operation currents.

AC performance of a novel carbon nanotube vacuum field emission differential amplifier IC

In this study, analytical modeling and AC measurements of the commom-mode rejection ratio (CMRR) of a single-chip carbon nanotube (CNT) vacuum field emission (VFE) differential amplifier (diff-amp) utilizing 2 mum conical-shaped CNT field emitter was presented. Dual-mask microfabrication process coupled with microwave plasma-enhanced chemical vapor deposition (MPCVD) growth of CNT emitters was employed to fabricate the matched VFE triode pairs with built-in split gates and integrated anodes to achieve a single-chip VFE diff-amp.

Development of Carbon Nanotubes Vacuum Field Emission Differential Amplifier Integrated Circuits

The device characteristics of the carbon nanotube (CNT) vacuum field emission (VFE) differential amplifier (diff-amp) is improved. The circuit-level characterization of the device was performed. SEM was used study the rectangular and circular arrays of the CNT triode array on the single chip VFE diff-amp

Carbon Nanotube Lateral Field Emitters with Metallic Anode

A lateral carbon nanotube (CNT) field emission device with a metallic anode is fabricated through a dual-mask microfabrication process complemented with a two-step microwave plasma-enhanced chemical vapor deposition. SEM was employed to characterize the structure of the fabricated device

Vertically aligned carbon nanotubes field emission devices fabricated by furnace thermal CVD at atmospheric pressure

In this paper, vertically aligned carbon nanotubes field emission devices were fabricated from the as grown carbon nanotubes (CNTs) by furnace thermal CVD at atmospheric pressure. The device was tested in vacuum (/spl sim/10/sup -6/ torr) for field emission characterization. The turn-on field was about 3 V//spl mu/m, which is comparable to data reported elsewhere.