Last summer, fifteen-year-old Jack Andraka hit the headlines with a test for pancreatic cancer that was faster, cheaper and more sensitive than current diagnostics. To create the test, he applied antibody-bound carbon nanotubes to filter paper: when the target antigen bound to the antibodies, small changes in conductance of the nanotubes was recorded.
The test wasn’t exactly new. At least one research paper (Nanotechnology (19 (46), 2008) used a similar “nanoscale oncometer” for breast cancer. But it did highlight the exciting possibilities of new materials and edged us closer to cost-effective personalized healthcare. The big question, for medicine and for other applications, is: when will this 'youtube' technology be commercialized? That question also came to mind this past autumn, when another carbon nanotube marvel hit the mainstream news: a sensor-drawing pencil. MIT researcher Katherine Mirica created a functioning gas sensor by literally drawing a carbon nanotube line between printed gold electrodes using a pencil tip shaped from carbon nanotube powder. The target gases are detected by monitoring changes in electrical conductivity. “The potential of our findings lies in the simplicity, versatility, and the solvent-free nature of this method […] It requires no specialized facilities or highly trained technicians. And nanotube-based pencils have the potential to be very stable formulations of sensing materials,” says Timothy Swager, leader of the MIT Chemistry group conducting the research. “Making sensors by drawing carbon nanotubes on the surface of paper could be very cost effective. We believe that the characteristics of our technology will accelerate the development of carbon nanotube-based sensors, and will lower the barrier to their commercial entry.” As with most truly innovative technologies, commercial success is not straightforward. “One step for further development is adapting this method to selective gas sensors for specific applications,” Swager continues. “Another is the thorough characterization of sensors for stability and the ability to operate at a variety of environmental conditions.” The group already has extensive experience with covalent and non-covalent chemical functionalization of the nanotubes. For example, they recently reported on the selective and sensitive detection of a fruit-ripening hormone (ethylene gas) using carbon nanotubes functionalized with a copper-containing compound. “We are now working towards applying these types of strategies for fabricating nanotube-based sensors by drawing,” says Swager. If development goes to plan, Swager believes the nanotube pencil-based diagnostics could hit the market within the year.
Talking Point: What are the potential applications and challenges of carbon nanotube-based sensors? Follow the discussion and share your opinions below.
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