Making Measurements on a Molecular Scale

Sensors Insights by Tom Kevan

Despite all the hype, commercialization of nanosensors is largely unfulfilled. Many of the potential beneficiaries have held back from adopting the technology and are waiting for proof that the nanodevices can be produced cost-effectively and function as promised under real-world conditions. According to Frost & Sullivan's report "Advances in Nanosensors", this wait-and-see environment is delaying commercialization and the emergence of sensor markets that leverage the technology's promise of "smaller, more sensitive, faster-responding, and less costly sensors." If you look hard enough, however, you can see signs that things are changing.

New Manufacturing Method
The nano werk article titled "Air quality measurements: New manufacturing method for gas nanosensors" chronicles the work of researchers at the Institute for Electron Microscopy and Nanoanalysis at Graz University of Technology, who have developed a manufacturing method of producing gas nanosensors using focused electron beam deposition (FEBID). This manufacturing technique promises to advance functionalization of nanostructures capable of measuring individual air components and to expand the range of applications in which gas nanosensors can be used.

This development is a turning point in nanosensor commercialization because those producing this type of sensor currently rely on a lithographic process that is overly complex and produces sensors that perform badly on uneven surfaces. The FEBID process works on uneven surfaces and produces powerful, sensitive, and responsive sensing devices. In addition, sensors manufactured with the new technique function well in liquid environments, opening the door for medical applications such as "direct measurement of individual blood components."

A Diamond in the Rough
Nanosensors are being used to identify and measure more than gases. The Next Big Future article "Quantum diamond nanosensors measure temperature in living cells and will be used for measuring magnetic and electric fields and for compact atomic clocks" looks at the work of researchers of DARPA's Quantum-Assisted Sensing and Readout (QuASAR) program. The research team recently demonstrated a method of using imperfections engineered into diamond known as nitrogen-vacancy (NV) color centers to measure and control temperature on a nanometer scale. These sensors are 100 nm in diameter and provide the means to monitor sub-degree variations in organic and inorganic material at length scales as low as 200 nanometers and over a broad temperature range.

The QuASAR team took its process one step further by implanting gold nanoparticles into a human cell adjacent to the diamond sensors. This allowed the researchers to manage and map temperature variations at the sub-cellular level by changing the output of a laser and by modifying the concentration of gold nanoparticles.

These quantum sensors open a new range of applications. For example, they could improve thermal management in electronics, provide insight into the structural integrity of advanced materials, and enable the treatment of diseases on the cellular level.

As stated by Jamil Abo-Shaeer, DARPA program manager for QuASAR, in the Next Big Future article, "This research provides another example of how the extreme precision and control of atomic physics techniques can impact sensing applications. It demonstrates that the novel measurement tools being developed under QuASAR can provide new capabilities … at scales that have not previously been possible."

Measuring Progress
Producing simpler, cost-effective manufacturing processes will go a long way toward advancing the commercialization of nanosensors. Add to that the prospect and benefits of measuring at the molecular level, and momentum toward broad adoption is bound to build.

Tom Kevan is a New Hampshire-based freelance writer specializing in technology.

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