Nanotechnology Project

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Environment, Health and Safety Research

A Nanocontact Sensor for Heavy Metal Ion Detection

Project Information

Principal InvestigatorNongjian Tao
InstitutionArizona State University
Project URLView
Relevance to ImplicationsMarginal
Class of NanomaterialEngineered Nanomaterials
Impact SectorEnvironment
Broad Research Categories Exposure
NNI identifier

Funding Information

Anticipated Total Funding$375,000.00
Annual Funding$187,500.00
Funding SourceEPA
Funding MechanismExtramural
Funding SectorGovernment
Start Year2002
Anticipated End Year2004


As materials and devices shrink to the nanometer scale, various quantum phenomena become important, which may lead to novel applications, including those that are important to environmental analysis and protection. This project exploits the phenomena of conductance quantization and quantum tunneling to fabricate nanoelectrodes for in situ detection of metal ion pollution. Our goal is to develop a high performance and low-cost sensor for initial on-site screening test of surface and groundwater to provide early warning and prevention of heavy metal ion pollution. The existing analytical techniques usually require preconcentration of samples to detect trace metal ions, which can be time consuming and prone to cross-contamination. Moreover, many of the sensitive techniques, such as inductively coupled plasma-mass spectrometry, are not suitable for on-site monitoring. In contrast, the nanocontact sensor has the potential of detecting even a few metal ions without preconcentration and is particularly suitable for on-site detecting ultratrace level of heavy metal ions, including radioactive elements.


The sensor consists of an array of nanoelectrode pairs on a silicon chip. The nanoelectrodes in each pair are separated with an atomic scale gap, which is achieved with the help of quantum tunneling phenomenon. Electrochemical deposition of even a few metal ions into the gap can bridge the gap and form a nanocontact between the nanoelectrodes, thus triggering a quantum jump in the electrical conductance. The sensor can achieve high specificity by combining several different measurements, such as redox potentials, point-contact spectroscopy and electrochemical potential-modulated conductance changes.

Expected Results:

We anticipate that this project will lead to a prototype nanocontact sensor for detecting heavy metal ion pollution in water. In addition to the unprecedented sensitivity, the sensor will be miniaturized and cost-effective, which should be particularly suitable for initial on-site screening test of polluted samples, thus leading to early warning and prevention of heavy metal ion pollution. The capability to measure and control electrochemical deposition/stripping of a single or a few metal ions to be fully developed in this project may provide opportunities for a better understanding of electroanalytical chemistry of metal ions, and lead to new environmentally benign fabrication methods for nanoelectronics.