Research Bits: Feb. 28

Single-molecule switch; electrodes grown in live tissue; controlled single-photon emitters.


Single-molecule switch

An international team of researchers have demonstrated a switch on a single fullerene molecule. Using a laser, the team switched the path of an incoming electron. “What we’ve managed to do here is control the way a molecule directs the path of an incoming electron using a very short pulse of red laser light,” said Project Researcher Hirofumi Yanagisawa from the University of Tokyo’s Institute for Solid State Physics. “Depending on the pulse of light, the electron can either remain on its default course or be redirected in a predictable way. So, it’s a little like the switching points on a train track, or an electronic transistor, only much faster. We think we can achieve a switching speed 1 million times faster than a classical transistor. And this could translate to real world performance in computing. But equally important is that if we can tune the laser to coax the fullerene molecule to switch in multiple ways at the same time, it could be like having multiple microscopic transistors in a single molecule. That could increase the complexity of a system without increasing its physical size.”

The team paper has been accepted by Physical Review Letters.  Light-induced subnanometric modulation of a single-molecule electron source, Phys. Rev. Lett. Hirofumi Yanagisawa, Markus Bohn, Hirotaka Kitoh-Nishioka, Florian Goschin, and Matthias F. Kling. Accepted18 January 2023

Electrodes grown in living tissue

A team of researchers from Linköping, Lund, and Gothenburg universities in Sweden have grown electrodes in living tissue, specifically zebrafish and medicinal leeches. Injecting a gel that has “assembly molecules”, which are enzymes, the team was able take advantage of the soft cells walls of animal cells (as opposed to plant cells, which are rigid). The gel interacts with the cells, creating soft, substrate-free, electronically conductive material. According to the researchers, the body’s endogenous molecules are enough to trigger the formation of electrodes. “Contact with the body’s substances changes the structure of the gel and makes it electrically conductive, which it isn’t before injection. Depending on the tissue, we can also adjust the composition of the gel to get the electrical process going,” says Xenofon Strakosas, researcher at LOE and Lund University and one of the study’s main authors.

The breakthrough has been years in the making, and it is hoped it could be used in the future to create an interface for restoring brain nerve functions. In the long-term, it could be the start of more complicated in-body electronic circuits “For several decades, we have tried to create electronics that mimic biology. Now we let biology create the electronics for us,” said Professor Magnus Berggren at the Laboratory for Organic Electronics, LOE, at Linköping University, in a press release.

The article is: Metabolite-induced in vivo fabrication of substrate-free organic bioelectronics; Xenofon Strakosas, Hanne Biesmans, Tobias Abrahamsson, Karin Hellman, Malin Silverå Ejneby, Mary J. Donahue, Peter Ekström, Fredrik Ek, Marios Savvakis, Martin Hjort, David Bliman, Mathieu Linares, Caroline Lindholm, Eleni Stavrinidou, Jennifer Y. Gerasimov, Daniel T. Simon, Roger Olsson, Magnus Berggren. Science 2023. Published online 23 February 2023 DOI: 10.1126/science.adc9998

Single-photon emitters

Physicists from the Helmholtz-Zentrum Dresden-Rossendorf (HZDR), TU Dresden, and Leibniz-Institut für Kristallzüchtung (IKZ) have controlled the release of photons using single-photon emitters, a key step that could help in developing better photonic integrated circuits (PICs). In the past rsearchers achieved random single-photon emitters, but this recent breakthrough of controlling the photon and making them uniform will make PIC manufacturing and use more feasible.  “Now, we show how focused ion beams from liquid metal alloy ion sources are used to place single-photon emitters at desired positions on the wafer while obtaining a high creation yield and high spectral quality”, says Dr. Nico Klingner, physicist, in a press release.

Passing the click test

Using a microphone and machine learning algorithms, researchers from the Oldenburg Branch for Hearing, Speech and Audio Technology HSA at Fraunhofer IDMT are proposing a device that can check for correct plug connections in automotive manufacturing by listening for and analyzing the sound of clicks.

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