Manufacturing Bits: Sept. 18
Closer Shaves
A startup is working on a technology that promises to give you a closer shave through semiconductor manufacturing technology. The startup, Nano-Sharp, is using silicon wafers to make razor blades and surgical tools that are cheaper than today’s technology.
Nano-Sharp is one of the new companies launched within the College of Engineering’s incubator at the University of California at Davis. The startup hopes to attract private funding to develop its crystalline blades.
Initially, Saif Islam, professor of electrical and computer engineering at UC Davis, was developing solar cells from silicon wafers. Islam’s team was etching the wafers to create thin vertical walls on the wafers. “We accidentally made some ‘bad’ walls that were very sharp,” said Islam, who is co-founder of Nano-Sharp, on UC Davis’ Web site. “We realized that we could mount them and use them as blades.”
Nano-Sharp co-founder Saif Islam, a UC Davis engineering professor, loads a silicon wafer into a machine that etches razor patterns. (Kevin Tong/UC Davis photo)
Today’s ceramic or silicon blades are sharp, but they are expensive. For example, a ceramic scalpel for eye surgery costs about $600, he said. Conventional blades are made by sharpening the edge of a silicon wafer.
In contrast, Nano-Sharp’s technique creates blades across the surface of the wafer at just a few atoms thick. “They have atomic sharpness approaching that of a diamond blade that metal blades cannot exhibit,” he added.
Researchers Devise Mammalian Cell Phones
ETH Zurich has devised what researchers call a mammalian cell phone. Researchers have reprogrammed mammalian cells, which can phone each other via chemical signals.
ETH utilized genes that can receive, process and respond to the signals. The mammalian “cell phone” could one day be used to halt the formation of diseases. “Communication is extremely important in controlling blood vessels, and we hope to be able to use synthetic ‘cell phones’ to correct or even cure disease-related cell communication systems precisely in the future with a therapeutic call,” said Martin Fussenegger at ETH Zurich’s Department of Biosystems Science and Engineering in Basel, on the research institute’s Web Site.
ETH devised the amino acid L-tryptophan from indole, which forms the sender cell. L-tryptophan produces acetaldehyde, which is the receiver cell. If acetaldehyde is produced or the indole is depleted, the sender cell stops producing L-tryptophan and the system switches off, according to researchers.
In the lab, ETH used human kidney cells to form modules. With these modules, the researchers formed other signal paths. This includes a signal cascade leading from the sender to the receiver cell. “This systematic communication network is quite literally a ‘cell phone’,” said Fussenegger.
New Memristor Materials
Oregon State University has devised a zinc-tin-oxide material that could pave the way for the long-awaited memristor.
The memristor, short for “memory resistor,” was postulated to be the fourth basic circuit element by Leon Chua of the University of California at Berkeley in 1971. A memristor is a passive two-terminal electronic device. In memristance, if the flow of a charge is stopped by turning off the applied voltage, this component will “remember” the last resistance that it had.
Hewlett-Packard hopes to commercialize the memristor in the form of a ReRAM. The challenge for the memristor is on the materials front. One proposed compound, indium gallium zinc oxide, is expensive. On the other hand, another transparent compound offered a better performance at lower cost, according to researchers.
OSU demonstrated that bipolar resistive switching is possible using an amorphous oxide semiconductor compound called zinc–tin-oxide (ZTO). Crossbar devices based on Al/ZTO/Pt showed promising switching ratios, long retention times, and good endurance.
The resistive switching in these devices is consistent with a combined filamentary/interfacial mechanism. Overall, ZTO shows potential as a low cost material for embedding memristive memory with thin film transistor logic for large area electronics.
“Flash memory has taken us a long way with its very small size and low price,” said John Conley, a professor in the OSU School of Electrical Engineering and Computer Science. “But it’s nearing the end of its potential, and memristors are a leading candidate to continue performance improvements.”
AFM Breakthroughs
IBM has been able to differentiate the chemical bonds in individual molecules using noncontact atomic force microscopy (AFM).
The results advance the exploration of molecules and atoms for use in potential graphene devices. In its research, IBM devised the bond order and length of individual carbon-carbon bonds in C60 and two planar polycyclic aromatic hydrocarbons (PAHs). C60 is also known as a buckyball, while the PAHs resemble small flakes of graphene.
The individual bonds between carbon atoms in such molecules differ in their length and strength. For the first time, these differences were detected for both individual molecules and bonds using AFM.
AFM makes use of a tiny tip, which is terminated with a single carbon monoxide molecule. This made it possible to distinguish individual bonds that differ only by 3 picometers, which is about one-hundredth of an atom’s diameter.
“We found two different contrast mechanisms to distinguish bonds. The first one is based on small differences in the force measured above the bonds. We expected this kind of contrast, but it was a challenge to resolve,” said IBM scientist Leo Gross, on the company’s Web site . “The second contrast mechanism really came as a surprise: Bonds appeared with different lengths in AFM measurements. With the help of ab initio calculations we found that the tilting of the carbon monoxide molecule at the tip apex is the cause of this contrast.”
—Mark LaPedus
Tags: atomic force microscopy, bipolar resistive switching, ETH Zurich, Hewlett-Packard, IBM, mammalian cell phones, memristors, Nano-Sharp, Oregon State University, ReRAM, UC Davis