Tag Archives: Jia Liu

Making nanoelectronic devices last longer in the body could lead to ‘cyborg’ tissue

An American Chemical Society (ACS) Feb. 19, 2014 news release (also on EurekAlert), describes some research devoted to extending a nanoelectronic device’s ‘life’ when implanted in the body,

The debut of cyborgs who are part human and part machine may be a long way off, but researchers say they now may be getting closer. In a study published in ACS’ journal Nano Letters, they report development of a coating that makes nanoelectronics much more stable in conditions mimicking those in the human body. [emphases mine] The advance could also aid in the development of very small implanted medical devices for monitoring health and disease.

Charles Lieber and colleagues note that nanoelectronic devices with nanowire components have unique abilities to probe and interface with living cells. They are much smaller than most implanted medical devices used today. For example, a pacemaker that regulates the heart is the size of a U.S. 50-cent coin, but nanoelectronics are so small that several hundred such devices would fit in the period at the end of this sentence. Laboratory versions made of silicon nanowires can detect disease biomarkers and even single virus cells, or record heart cells as they beat. Lieber’s team also has integrated nanoelectronics into living tissues in three dimensions — creating a “cyborg tissue.” One obstacle to the practical, long-term use of these devices is that they typically fall apart within weeks or days when implanted. In the current study, the researchers set out to make them much more stable.

They found that coating silicon nanowires with a metal oxide shell allowed nanowire devices to last for several months. This was in conditions that mimicked the temperature and composition of the inside of the human body. In preliminary studies, one shell material appears to extend the lifespan of nanoelectronics to about two years.

Depending on how you define the term cyborg, it could be said there are already cyborgs amongst us as I noted in an April 20, 2012 posting titled: My mother is a cyborg. Personally I’m fascinated by the news release’s mention of ‘cyborg tissue’ although there’s no further explanation of what the term might mean.

For the curious, here’s a link to and a citation for the paper,

Long Term Stability of Nanowire Nanoelectronics in Physiological Environments by Wei Zhou, Xiaochuan Dai, Tian-Ming Fu, Chong Xie, Jia Liu, and Charles M. Lieber. Nano Lett., Article ASAP DOI: 10.1021/nl500070h Publication Date (Web): January 30, 2014
Copyright © 2014 American Chemical Society

This paper is behind a paywall.

Clone your carbon nanotubes

The Nov. 14, 2012 news release on EurekAlert highlights some work on a former nanomaterial superstar, carbon nanotubes,

Scientists and industry experts have long speculated that carbon nanotube transistors would one day replace their silicon predecessors. In 1998, Delft University built the world’s first carbon nanotube transistors – carbon nanotubes have the potential to be far smaller, faster, and consume less power than silicon transistors.

A key reason carbon nanotubes are not in your computer right now is that they are difficult to manufacture in a predictable way. Scientists have had a difficult time controlling the manufacture of nanotubes to the correct diameter, type and ultimately chirality, factors that control nanotubes’ electrical and mechanical properties.

Carbon nanotubes are typically grown using a chemical vapor deposition (CVD) system in which a chemical-laced gas is pumped into a chamber containing substrates with metal catalyst nanoparticles, upon which the nanotubes grow. It is generally believed that the diameters of the nanotubes are determined by the size of the catalytic metal nanoparticles. However, attempts to control the catalysts in hopes of achieving chirality-controlled nanotube growth have not been successful.

The USC [University of Southern California] team’s innovation was to jettison the catalyst and instead plant pieces of carbon nanotubes that have been separated and pre-selected based on chirality, using a nanotube separation technique developed and perfected by Zheng [Ming Zheng] and his coworkers at NIST [US National Institute of Standards and Technology]. Using those pieces as seeds, the team used chemical vapor deposition to extend the seeds to get much longer nanotubes, which were shown to have the same chirality as the seeds..

The process is referred to as “nanotube cloning.” The next steps in the research will be to carefully study the mechanism of the nanotube growth in this system, to scale up the cloning process to get large quantities of chirality-controlled nanotubes, and to use those nanotubes for electronic applications

H/T to ScienceDaily’s Nov. 14, 2012 news item for the full journal reference,

Jia Liu, Chuan Wang, Xiaomin Tu, Bilu Liu, Liang Chen, Ming Zheng, Chongwu Zhou. Chirality-controlled synthesis of single-wall carbon nanotubes using vapour-phase epitaxy. Nat. Commun., 13 Nov, 2012 DOI: 10.1038/ncomms2205

The article is behind a paywall.