How to See Clearly in the Night

Researchers from The Australian National University (ANU) have developed new technology that allows people to see clearly in the dark, revolutionising night-vision. The first-of-its-kind thin film, described in a new article published in Advanced Photonics, is ultra-compact and one day could work on standard glasses. The researchers say the new prototype tech, based on nanoscale crystals, could be used for defence, as well as making it safer to drive at night and walking home after dark. The team also say the work of police and security guards – who regularly employ night vision – will be easier and safer, reducing chronic neck injuries from currently bulk night-vision devices.

We have made the invisible visible,” lead researcher Dr Rocio Camacho Morales said. “Our technology is able to transform infrared light, normally invisible to the human eye, and turn this into images people can clearly see – even at distance.

We’ve made a very thin film, consisting of nanometre-scale crystals, hundreds of times thinner than a human hair, that can be directly applied to glasses and acts as a filter,  allowing you to see in the darkness of the night.”

The technology is extremely lightweight, cheap and easy to mass produce, making them accessible to everyday users. Currently, high-end infrared imaging tech requires cryogenic freezing to work and are costly to produce. This new tech works at room temperatures. Dragomir Neshev, Director of the ARC Centre for Excellence in Transformative Meta-Optical Systems (TMOS) and ANU Professor in Physics, said the new tech used meta-surfaces, or thin films, to manipulate light in new ways.

“This is the first time anywhere in the world that infrared light has been successfully transformed into visible images in an ultra-thin screen,” Professor Neshev said.

 

Source: https://www.anu.edu.au/

Electrified Tattoos and Personalized Biosensors

Electrical engineers at Duke University have devised a fully print-in-place technique for electronics that is gentle enough to work on delicate surfaces including paper and human skin. The advance could enable technologies such as high-adhesion, embedded electronic tattoos and bandages tricked out with patient-specific biosensors.

Two electronically active leads directly printed along the underside of Duke graduate student Nick Williams’s pinky successfully light up an LED when a voltage is applied

When people hear the term ‘printed electronics,’ the expectation is that a person loads a substrate and the designs for an electronic circuit into a printer and, some reasonable time later, removes a fully functional electronic circuit,” said Aaron Franklin, Associate Professor at Duke.

“Over the years there have been a slew of research papers promising these kinds of ‘fully printed electronics,’ but the reality is that the process actually involves taking the sample out multiple times to bake it, wash it or spin-coat materials onto it,” Franklin said. “Ours is the first where the reality matches the public perception.

The concept of so-called electronic tattoos were first developed in the late 2000s at the University of Illinois by John A. Rogers, who is now Professor of Materials Science and Engineering at Northwestern University. Rather than a true tattoo that is injected permanently into the skin, Rogers’s electronic tattoos are thin, flexible patches of rubber that contain equally flexible electrical components.

The thin film sticks to skin much like a temporary tattoo, and early versions of the flexible electronics were made to contain heart and brain activity monitors and muscle stimulators. While these types of devices are on their way to commercialization and large-scale manufacturing, there are some arenas in which they’re not well suited, such as when direct modification of a surface by adding custom electronics is needed. “For direct or additive printing to ever really be useful, you’re going to need to be able to print the entirety of whatever you’re printing in one step,” said Franklin. “Some of the more exotic applications include intimately connected electronic tattoos that could be used for biological tagging or unique detection mechanisms, rapid prototyping for on-the-fly custom electronics, and paper-based diagnostics that could be integrated readily into customized bandages.”

The techniques are described in a series of papers published in the journal Nanoscale and in the journal ACS Nano.

Source: https://pratt.duke.edu/

Let Your Skin Play Music

A variety of nanomaterials have been used over the years in loudspeakers and microphones. Nanoparticles have replaced permanent magnets in loudspeakers and a thin film of carbon nanotubes has done pretty much the same. And, of course, someone tried to use graphene to reproduce sound for microphones.

Now researchers at Ulsan National Institute of Science and Technology (UNIST) in South Korea have made a nanomembrane out of silver nanowires to serve as flexible loudspeakers or microphones. The researchers even went so far as to demonstrate their nanomembrane by making it into a loudspeaker that could be attached to skin and used it to play the final movement of a violin concerto—namely, La Campanella by Niccolo Paganini.

In research described in the journal Science Advances, the Korean researchers embedded a silver nanowire network within a polymer-based nanomembrane. The decision to use silver nanowires rather than the other types of nanomaterials that have been used in the past was based on the comparative ease of hybridizing the nanowires into the polymer. In addition, the researchers opted for nanowires because the other materials like graphene and carbon nanotubes are not as mechanically strong at nanometer-scale thickness when in freestanding form, according to Hyunhyub Ko, an associate professor at UNIST and coauthor of the research. It is this thickness that is the critical element of the material.

The biggest breakthrough of our research is the development of ultrathin, transparent, and conductive hybrid nanomembranes with nanoscale thickness, less than 100 nanometers,” said Ko. “These outstanding optical, electrical, and mechanical properties of nanomembranes enable the demonstration of skin-attachable and imperceptible loudspeaker and microphone.”

The nanomembrane loudspeaker operates by emitting thermoacoustic sound through the oscillation of the surrounding air brought on by temperature differences. The periodic Joule heating that occurs when an electric current passes through a conductor and produces heat leads to these temperature oscillations.

Source: https://spectrum.ieee.org/