Category Chemistry/Nanotechnology

Schematic depiction of different energy terms contributing to the adsorption energy, and charge density difference of 2H-P after adsorption onto Cu(111) at 12.8 Angstrom separation. Credit: M. Müller/TU Munich

As we continue to shrink electronic components, top-down manufacturing methods begin to approach a physical limit at the nanoscale. A solution involves bottom-up self-assembly of molecular building blocks to build nanoscale devices.

Successful self-assembly is an elaborately choreographed dance, in which the attractive and repulsive forces within molecules, between each molecule and its neighbors, and between molecules and the surface that supports them, have to all be taken into account...

This is the NIST concept for DNA sequencing through a graphene nanopore. Credit: Smolyanitsky/NIST

Researchers at NIST have simulated a new concept for rapid, accurate gene sequencing by pulling a DNA molecule through a tiny, chemically activated hole in graphene and detecting changes in electrical current. The method could identify about 66 billion bases/s with 90% accuracy and no false +ves. If demonstrated experimentally, the NIST method might ultimately be faster and cheaper than conventional DNA sequencing, meeting a critical need for applications such as forensics.

Conventional sequencing, developed in the 1970s, involves separating, copying, labeling and reassembling pieces of DNA to read the genetic information...

When cracks form, microbeads embedded in the material break open and cause a chemical reaction that highlights the damaged area. Credit: Image courtesy Nancy Sottos

Damage developing in a material can be difficult to see until something breaks or fails. A new polymer damage indication system automatically highlights areas that are cracked, scratched or stressed, allowing engineers to address problem areas before they become more problematic. The early warning system would be particularly useful in applications like petroleum pipelines, air and space transport, and automobiles – applications where one part’s failure could have costly ramifications that are difficult to repair.

“Polymers are susceptible to damage in the form of small cracks that are often difficult to detect...

Stanford researchers are using spiky nanoparticles of graphene-coated nickel to create a lithium-ion battery that shuts down when it’s too hot, then quickly restarts when it cools (1µ =1 micrometer). Credit: Zheng Chen, Stanford University

The new technology could prevent the kind of fires that have prompted recalls and bans on a wide range of battery-powered devices, from recliners and computers to navigation systems and hoverboards. “People have tried different strategies to solve the problem of accidental fires in lithium-ion batteries,” said Prof. Zhenan Bao, chemical engineering, Stanford. It “can be shut down and revived over repeated heating and cooling cycles without compromising performance.”

A typical Li-ion battery consists of 2 electrodes and a liquid or gel electrolyte that c...