Nano-Sensor Detects SARS-CoV-2

Using specialized carbon nanotubes, MIT engineers have designed a novel sensor that can detect SARS-CoV-2 without any antibodies, giving a result within minutes. Their new sensor is based on technology that can quickly generate rapid and accurate diagnostics, not just for Covid-19 but for future pandemics, the researchers say.

Using specialized carbon nanotubes, MIT engineers have designed a novel sensor that can detect SARS-CoV-2 without any antibody, giving a result within minutes.

A rapid test means that you can open up travel much earlier in a future pandemic. You can screen people getting off of an airplane and determine whether they should quarantine or not. You could similarly screen people entering their workplace and so forth,” says Michael Strano, the Carbon P. Dubbs Professor of Chemical Engineering at MIT and the senior author of the study. “We do not yet have technology that can develop and deploy such sensors fast enough to prevent economic loss.”

The diagnostic is based on carbon nanotube sensor technology that Strano’s lab has previously developed. Once the researchers began working on a Covid-19 sensor, it took them just 10 days to identify a modified carbon nanotube capable of selectively detecting the viral proteins they were looking for, and then test it and incorporate it into a working prototype. This approach also eliminates the need for antibodies or other reagents that are time-consuming to generate, purify, and make widely available.

Several years ago, Strano’s lab developed a novel approach to designing sensors for a variety of molecules. Their technique relies on carbon nanotubeshollow, nanometer-thick cylinders made of carbon that naturally fluoresce when exposed to laser light. They have shown that by wrapping such tubes in different polymers, they can create sensors that respond to specific target molecules by chemically recognizing them.

Their approach, known as Corona Phase Molecular Recognition (CoPhMoRe), takes advantage of a phenomenon that occurs when certain types of polymers bind to a nanoparticle. Known as amphiphilic polymers, these molecules have hydrophobic regions that latch onto the tubes like anchors and hydrophilic regions that form a series of loops extending away from the tubes.

MIT postdoc Sooyeon Cho and graduate student Xiaojia Jin are the lead authors of the paper, which appears today in Analytical Chemistry. Other authors include MIT graduate students Sungyun Yang and Jianqiao Cui, and postdoc Xun Gong.


Noise-cancelling Windows Halve Traffic Sounds

People living in cities with warm climates face a problem during summer months: keeping windows open for ventilation means letting in traffic sounds. A noise-cancelling device could solve this dilemma. Bhan Lam at the Nanyang Technological University in Singapore and his colleagues have created a device that can halve the noisiness of urban traffic, reducing the sound coming through an open window by up to 10 decibels.

To cancel out road noise, the researchers used 24 small loudspeakers and fixed these to the security grilles of a typical window in Singapore in an 8×3 grid. These grilles are a common feature across South-East Asia, says Lam. He adds that the spacing of the speakers was dependent on the frequency of the noise that they wanted to cancel out.

The researchers spaced each speaker 12.5 centimetres apart facing outwards and programmed them to emit sounds at the same frequency of noise detected by a sensor placed outside the window. The device was most successful at cancelling noise between frequencies of 300 and 1000 Hz, with up to a 50 per cent reduction in loudness for sounds within this range. It isn’t optimised for the noise from human voices, which have higher frequencies.

The effect is similar to the technology used in noise-cancelling headphones, which are often tuned specifically to cancel out the hum of aircraft engines”, says Lam. “The speakers the team used were only 4.5 centimetres in diameter – too small to cancel out noise at frequencies below 300 Hz. “A speaker needs to move a huge volume of air for low frequency sounds.

The team placed the window in a replica room and played road traffic, train and aircraft noise from another loudspeaker 2 metres away. The frequency of most of the noise from traffic and passing aircraft ranges from 200 to 1000 hertz. Large trucks and motorcycles tend to generate sounds on the lower end of the range, while the majority of the sound from  is around 1000 Hz.


New Biosensor Measures The Concentration Of Covid-19 In The Air

A team of researchers from Empa, ETH Zurich and Zurich University Hospital has succeeded in developing a novel sensor for detecting the new coronavirus. In future it could be used to measure the concentration of the virus in the environment – for example in places where there are many people or in hospital ventilation systems.

Jing Wang and his team at Empa and ETH Zurich usually work on measuring, analyzing and reducing airborne pollutants such as aerosols and artificially produced nanoparticles. However, the challenge the whole world is currently facing is also changing the goals and strategies in the research laboratories. The new focus: a sensor that can quickly and reliably detect SARS-CoV-2 – the new coronavirus.

But the idea is not quite so far removed from the group’s previous research work: even before the COVID-19 began to spread, first in China and then around the world, Wang and his colleagues were researching sensors that could detect bacteria and viruses in the air. The sensor will not necessarily replace the established laboratory tests, but could be used as an alternative method for clinical diagnosis, and more prominently to measure the virus concentration in the air in real time: For example, in busy places like train stations or hospitals.

Fast and reliable tests for the new coronavirus are urgently needed to bring the pandemic under control as soon as possible. Most laboratories use a molecular method called reverse transcription polymerase chain reaction, or RT-PCR for short, to detect viruses in respiratory infections. This is well established and can detect even tiny amount of viruses – but at the same time it can be time consuming and prone to error.

Jing Wang and his team have developed an alternative test method in the form of an optical biosensor. The sensor combines two different effects to detect the virus safely and reliably: an optical and a thermal one.

The sensor uses an optical and a thermal effect to detect the COVID-19-Virus safely and reliably

The sensor is based on tiny structures of gold, so-called gold nanoislands, on a glass substrate. Artificially produced DNA receptors that match specific RNA sequences of the SARS-CoV-2 are grafted onto the nanoislands. The coronavirus is a so-called RNA virus: Its genome does not consist of a DNA double strand as in living organisms, but of a single RNA strand. The receptors on the sensor are therefore the complementary sequences to the virus’ unique RNA sequences, which can reliably identify the virus.

The technology the researchers use for detection is called LSPR, short for localized surface plasmon resonance. This is an optical phenomenon that occurs in metallic nanostructures: When excited, they modulate the incident light in a specific wavelength range and create a plasmonic near-field around the nanostructure. When molecules bind to the surface, the local refractive index within the excited plasmonic near-field changes. An optical sensor located on the back of the sensor can be used to measure this change and thus determine whether the sample contains the RNA strands in question.


Edible Sensor To Check Whether Drugs Have Been Taken

An ingestible sensor that enables health workers to check that patients have taken their medication could revolutionise tuberculosis treatment, particularly in developing countries, researchers believe. New ways to ensure TB patients comply with their treatment are desperately needed. Patients with the most straightforward form of the deadly infectious disease have to take a cocktail of drugs over a six-month period – and if they fail to stick to the regime, they risk the disease returning in a drug-resistant form.

In the study, published in in the journal Plos Medicinepatients in California were given a standard TB drug alongside an “ediblesensor, coated with minerals.  When ingested, the sensor communicates with a patch attached to the patient’s torso that in turn sends a message to a mobile phone. The data is then automatically uploaded to a secure, centralised computer for a health worker to check.

To avoid high treatment drop-out rates it is recommended that patients take their medication under the supervision of a health worker in a procedure called directly observed therapy (DOT). But this is time consuming – requiring a health worker to visit the patient at work or home or vice versa – as well as costly and inconvenient. But this new “wireless observed therapy” (WOT) avoids the need for daily visits and enables the patient to take the drugs in private and at a time that suits them.

Some 77 patients, who were no longer infectious but still needed to finish their course of treatment, took part in the study, carried out by researchers at the University of California San Diego (UCSD). A third followed the standard DOT model of care and two thirds followed the novel treatment. The study showed that WOT had a 99.3 per cent accuracy rate in recording adherence to treatment and all those patients on the wireless therapy wanted to continue with it after the trial had ended. All finished treatment and were cured of TB.

Sara Browne, lead author of the study and associate professor of infectious diseases at the UCSD, said the ingestible sensor gave patients more autonomy.

The system allows patients to determine how they want to take their pills with minimum interference. It preserves the highest standards of privacy but it also enables the health system to focus on people who need the most support,” she said.


Artificial Skin Recreates The Human Sense Of Pain

Prosthetic technology has taken huge strides in the last decade, but accurately simulating human-like sensation is a difficult task. New “electronic skin” technology developed at the Daegu Gyeongbuk Institute of Science and Technology (DGIST) in Korea could help replicate advanced “pain” sensations in prosthetics, and enable robots to understand tactile feedback, like the feeling of being pricked, or that of heat on skin.

Trying to recreate the human senses has been a driver of technologies throughout the 20thcentury, like TV or audio playback. Mimicry of tactile sensing has been a focus of several different research groups in the last few years, but advances have mainly improved the feeling of pressure and strength in prosthetics. Human sensation, however, can detect much more subtle cues. The DGIST researchers, led by Department of Information and Communication Engineering Professor Jae Eun Jang, needed to bring together expertise from several different fields to begin the arduous task of replicating these more complex sensations in their electronic skin, working with colleagues in DGIST’s Robotics and Brain Sciences departments.

“We have developed a core base technology that can effectively detect pain, which is necessary for developing future-type tactile sensor. As an achievement of convergence research by experts in nano engineering, electronic engineering, robotics engineering, and brain sciences, it will be widely applied on electronic skin that feels various senses as well as new human-machine interactions.” Jang explained.

The DGIST team effort has created a more efficient sensor technology, able to simultaneously detect pressure and heat. They also developed a signal processing system that adjusted pain responses depending on pressure, area, and temperature.


Artificial Skin Opens SuperHuman Perception

A new type of sensor could lead to artificial skin that someday helps burn victimsfeel’ and safeguards the rest of us, University of Connecticut (UConn)  researchers suggest in a paper in Advanced Materials.

Our skin’s ability to perceive pressure, heat, cold, and vibration is a critical safety function that most people take for granted. But burn victims, those with prosthetic limbs, and others who have lost skin sensitivity for one reason or another, can’t take it for granted, and often injure themselves unintentionally. Chemists Islam Mosa from UConn, and James Rusling from UConn and UConn Health, along with University of Toronto engineer Abdelsalam Ahmed, wanted to create a sensor that can mimic the sensing properties of skin. Such a sensor would need to be able to detect pressure, temperature, and vibration. But perhaps it could do other things too, the researchers thought.

It would be very cool if it had abilities human skin does not; for example, the ability to detect magnetic fields, sound waves, and abnormal behaviors,” said Mosa.

Mosa and his colleagues created such a sensor with a silicone tube wrapped in a copper wire and filled with a special fluid made of tiny particles of iron oxide just one billionth of a meter long, called nanoparticles. The nanoparticles rub around the inside of the silicone tube and create an electric current. The copper wire surrounding the silicone tube picks up the current as a signal. When this tube is bumped by something experiencing pressure, the nanoparticles move and the electric signal changes. Sound waves also create waves in the nanoparticle fluid, and the electric signal changes in a different way than when the tube is bumped.

The researchers found that magnetic fields alter the signal too, in a way distinct from pressure or sound waves. Even a person moving around while carrying the sensor changes the electrical current, and the team found they could distinguish between the electrical signals caused by walking, running, jumping, and swimming.

Metal skin might sound like a superhero power, but this skin wouldn’t make the wearer Colossus from the X-men. Rather, Mosa and his colleagues hope it could help burn victimsfeelagain, and perhaps act as an early warning for workers exposed to dangerously high magnetic fields. Because the rubber exterior is completely sealed and waterproof, it could also serve as a wearable monitor to alert parents if their child fell into deep water in a pool, for example.


Electronic Skin To Restore Sense Of Pain

Amputees often experience the sensation of a “phantom limb”—a feeling that a missing body part is still there. That sensory illusion is closer to becoming a reality thanks to a team of engineers at the Johns Hopkins University that has created an electronic skin. When layered on top of prosthetic hands, this e-dermis brings back a real sense of touch through the fingertips.


After many years, I felt my hand, as if a hollow shell got filled with life again,” says the anonymous amputee who served as the team’s principal volunteer tester.

Made of fabric and rubber laced with sensors to mimic nerve endings, e-dermis recreates a sense of touch as well as pain by sensing stimuli and relaying the impulses back to the peripheral nerves.

We’ve made a sensor that goes over the fingertips of a prosthetic hand and acts like your own skin would,” explains Luke Osborn, a graduate student in biomedical engineering. “It’s inspired by what is happening in human biology, with receptors for both touch and pain“This is interesting and new,” Osborn adds, “because now we can have a prosthetic hand that is already on the market and fit it with an e-dermis that can tell the wearer whether he or she is picking up something that is round or whether it has sharp points.”

The work in the journal Science Robotics – shows it is possible to restore a range of natural, touch-based feelings to amputees who use prosthetic limbs. The ability to detect pain could be useful, for instance, not only in prosthetic hands but also in lower limb prostheses, alerting the user to potential damage to the device.

Human skin contains a complex network of receptors that relay a variety of sensations to the brain. This network provided a biological template for the research team, which includes members from the Johns Hopkins departments of Biomedical Engineering, Electrical and Computer Engineering, and Neurology, and from the Singapore Institute of Neurotechnology.

Bringing a more human touch to modern prosthetic designs is critical, especially when it comes to incorporating the ability to feel pain, Osborn states. “Pain is, of course, unpleasant, but it’s also an essential, protective sense of touch that is lacking in the prostheses that are currently available to amputees,” he says. “Advances in prosthesis designs and control mechanisms can aid an amputee’s ability to regain lost function, but they often lack meaningful, tactile feedback or perception.


Strain Improves Performance of Atomically Thin Semiconductor

Researchers in UConn’s Institute of Materials Science significantly improved the performance of an atomically thin semiconductor material by stretching it, an accomplishment that could prove beneficial to engineers designing the next generation of flexible electronics, nano devices, and optical sensors.

In a study appearing in the research journal Nano Letters, Michael Pettes, assistant professor of mechanical engineering, reports that a six-atom thick bilayer of tungsten diselenide exhibited a 100-fold increase in photoluminescence when it was subjected to strain. The material had never exhibited such photoluminescence before.

The findings mark the first time scientists have been able to conclusively show that the properties of atomically thin materials can be mechanically manipulated to enhance their performance, Pettes says. Such capabilities could lead to faster computer processors and more efficient sensors.

The process the researchers used to achieve the outcome is also significant in that it offers a reliable new methodology for measuring the impact of strain on ultrathin materials, something that has been difficult to do and a hindrance to innovation.

Experiments involving strain are often criticized since the strain experienced by these atomically thin materials is difficult to determine and often speculated as being incorrect,” says Pettes. “Our study provides a new methodology for conducting strain-dependent measurements of ultrathin materials, and this is important because strain is predicted to offer orders of magnitude changes in the properties of these materials across many different scientific fields.”