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Real-Time Intelligent Chemical and Biological Nanosensors on a Flexible Platform

Carbon nanotubes are used to fabricate multiple arrays of switching devices.

The objectives of this research are to examine the feasibility of real-time sensing of chemical and biological species by using the unique materials and electronic properties of carbon nanotubes, and to demonstrate the multi-agent sensing and information processing capabilities of such devices.

The current rectification property of chemical-vapor-deposited (CVD), as-grown, single-walled carbon nanotubes (SWNTs) was investigated. The long strands of SWNT bundles were used to fabricate multiple arrays of switching devices with channel lengths of 3, 5, 7, and 10um on a 15×15mm2 silicon dioxide (SiO2) on silicon (Si) substrate. The devices were fabricated by photolithographically depositing a 100-nm layer of gold (Au) on top of 10-nm-thick titanium (Ti) to serve as electrodes with varying source (S) and drain (D) separation. The dimension of each electrode pad was 250 × 250 um. The samples were then annealed at 200°C for 30 minutes in constant flow of nitrogen to eliminate possible oxide defects.

AFM topographical image (a) of as-grown CVD Nanotubes, and (b) the related height profile.
A majority of the fabricated devices, regardless of channel length, showed current rectification characteristics with high throughput of current (I) in the forward bias (V). Atomic force microscope (AFM) analysis of the device structure and surface topology of SWNTs suggests the observed rectification of current results from surface irregularities and is possibly due to change in the chirality of a single tube. Using fabricated SWNT field-effect transistors (FETs), the effects of gases, particularly O2 and N2, were demonstrated on the fabricated devices.

The present process is compatible with current industry-standard silicon electronics and could be easily transitioned for mass fabrication of the SWNT switching devices. The increase in current magnitude in the presence of oxygen and nitrogen shows that the devices composed of SWNTs can be used in sensor applications.

This work was done by Govind Mallick and Shashi P. Karna of the Army Research Laboratory. For more information, download the Technical Support Package (free white paper) at www.defensetechbriefs.com/tsp  under the Materials category. ARL-0076

Topics:
Chemicals Electronic equipment Fabrication Gases Manufacturing processes Materials Oxygen Research and development Sensors and actuators Test facilities Transistors
This Brief includes a Technical Support Package (TSP).
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Real-Time Intelligent Chemical and Biological Nanosensors on a Flexible Platform

(reference ARL-0076) is currently available for download from the TSP library.

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    Defense Tech Briefs Magazine

    This article first appeared in the April, 2010 issue of Defense Tech Briefs Magazine (Vol. 4 No. 2).

    Read more articles from this issue here.

    Read more articles from the archives here.

    Overview

    The document titled "Real-time Intelligent Chemical and Biological Nanosensors on Flexible Platform - II," authored by Govind Mallick and Shashi P. Karna, presents research conducted by the U.S. Army Research Laboratory, focusing on the development of advanced nanosensor technologies for the real-time detection of chemical and biological agents. The report, dated March 2009, covers research conducted from October 1, 2007, to September 30, 2008.

    The primary objective of the research is to create intelligent nanosensors that can operate on flexible platforms, enhancing their applicability in various environments, including military and civilian settings. The report outlines the background of nanosensor technology, emphasizing the need for rapid and accurate detection methods for hazardous substances. It discusses the advantages of using nanosensors, such as their high sensitivity, low detection limits, and potential for miniaturization.

    The approach taken in the research involves the integration of nanomaterials with flexible substrates to develop sensors that can detect specific chemical and biological agents in real-time. The document details the experimental methods employed, including the synthesis of nanomaterials, sensor fabrication, and testing procedures. The results section presents findings on the performance of the developed sensors, highlighting their effectiveness in detecting target analytes under various conditions.

    The discussion section analyzes the implications of the results, addressing challenges faced during the research and potential improvements for future work. The authors emphasize the importance of continued research in this field to enhance the reliability and functionality of nanosensors, which could significantly impact safety and security measures.

    In conclusion, the report summarizes the key findings and suggests directions for future research, including the exploration of new materials and technologies to further improve sensor performance. The document serves as a valuable resource for researchers and practitioners interested in the field of chemical and biological detection, providing insights into the state of nanosensor technology and its potential applications.

    Overall, this report contributes to the understanding of how flexible nanosensors can be developed and utilized for real-time monitoring of hazardous agents, underscoring the importance of innovation in detection technologies for both military and civilian applications.

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