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Nanotechnology spans many disciplines

Nanotechnologist and co-founder of the Black in Nanotech initiative, Olivia Geneus. (Courtesy: Alexander Harold) Welcome to this Physics World Nanotechnology Briefing, which showcases the breadth of applications of modern nanotechnology.

Olivia Geneus is one of the growing number of scientists who are developing nanotechnologies for medicine. In an interview, the PhD student at the State University of New York at Buffalo explains how she is developing nanoparticles designed to cross the blood–brain barrier in order to image and destroy brain cancer cells. Geneus also talks about Black in Nanotech Week, which she co-founded, and the need to encourage Black children to consider careers in science.

Ed Lester of the UK’s University of Nottingham knows that there are myriad uses for nanoparticles. In 2007 he founded the company Promethean Particles when he realized industrial users were not able to source nanoparticles in the quantities and quality that they required. In an interview, Lester talks about some of the company’s development projects including nanoparticles for aviation, healthcare and energy.

Nanomesh pressure sensor preserves skin’s sense of touch

Takao Someya and colleagues at the University of Tokyo have developed the first artificial-skin patch that does not affect the touch sensitivity of the real skin beneath it. The new ultrathin sensor could be used in applications as diverse as prosthetics and human-machine interfaces.

“A wearable sensor for your fingers has to be extremely thin,” explains Tokyo’s Sunghoon Lee. “But this obviously makes it very fragile and susceptible to damage from rubbing or repeated physical actions.” For this reason most e-skins developed to date been relatively thick and bulky.

In contrast, the sensor developed by the Tokyo team is thin and porous and consists of two layers (Science 370 966). The first layer is an insulating mesh-like network comprising polyurethane fibres around 200–400 nm thick. The second layer is a network of lines that makes up the functional electronic part of the device – a parallel-plate capacitor. This is made of gold on a supporting scaffold of polyvinyl alcohol (PVA), a water-soluble polymer often found in contact lenses. Once this layer has been fabricated, the PVA is washed away to leave only the gold support. The finished pressure sensor is around 13 μ m thick.

Nanotube artificial muscles pick up the pace

An electrochemically powered artificial muscle made from twisted carbon nanotubes contracts more when driven faster thanks to a novel conductive polymer coating. Developed by Ray Baughman of the University of Texas at Dallas in the US and an international team, the device overcomes some of the limitations of previous artificial muscles, and could have applications in robotics, smart textiles and heart pumps.

Carbon nanotubes (CNTs) are rolled-up sheets of carbon with walls as thin as a single atom. When twisted together to form a yarn and placed in an electrolyte bath, CNTs expand and contract in response to electrochemical inputs, much like a natural muscle. In a typical set-up, a potential difference between the yarn and an electrode drives ions from the electrolyte into the yarn, causing the muscle to actuate.

While such CNT muscles are highly energy efficient and extremely strong – they can lift loads up to 100,000 times their own weight – they do have limitations. The main one is that they are bipolar, meaning that the direction of their movement switches whenever the potential drops to zero. This reduces the overall stroke of the actuator. Another drawback is that the muscle’s capacitance decreases when the potential is changed quickly, which also causes the stroke to decrease.

Cancer trial delivers ‘unheard-of’ result: complete remission for everyone

A small trial of a new cancer drug has reportedly provided a result never before seen — the total remission of cancer in all of its participants.

According to a report in the New England Journal of Medicine, a dozen rectal cancer patients saw their tumors disappear completely after they received an experimental drug called dostarlimab.

“I believe this is the first time this has happened in the history of cancer,” Dr. Luis Alberto Diaz Jr., one of the trial leaders and a medical oncologist at Memorial Sloan Kettering (MSK) Cancer Center, told The New York Times.

Self-sensing artificial muscle-based on liquid crystal elastomer and low-melting point alloys

Materials scientists and bioengineers at the intersection of regenerative medicine and bioinspired materials seek to develop shape-programmable artificial muscles with self-sensing capabilities for applications in medicine. In a new report now published in Science Advances, Haoran Liu and a team of researchers in systems and communications engineering at the Frontier Institute of Science and Technology, Jiaotong University, China, were inspired by the coupled behavior of muscles, bones, and nerve systems of mammals and other living organisms to create a multifunctional artificial muscle in the lab. The construct contained polydopamine-coated liquid crystal elastomer (LCE) and low-melting point alloys (LMPA) in a concentric tube or rod. While the team adopted the outer liquid crystal-elastomer to mimic reversible contraction and recovery, they implemented the inner low-melting point alloy for deformation locking and to detect resistance mechanics, much like bone and nerve functions, respectively. The artificial muscle demonstrated a range of performances, including regulated bending and deformation to support heavy objects, and is a direct and effective approach to the design of biomimetic soft devices.

Soft robotics inspired by the skeleton–muscle–nerve system

Scientists aim to implement biocompatibility between soft robotic elements and human beings for assisted movement and high load-bearing capacity; however, such efforts are challenging. Most traditional robots are still in use in industrial, agricultural and aerospace settings for high-precision sensor-based, load-bearing applications. Several functional soft robots contrastingly depend on materials to improve the security of human-machine interactions. Soft robots are therefore complementary to hard robots and have tremendous potential for applications. Biomimetic constructs have also provided alternative inspiration to emulate the skeleton-muscle-nerve system to facilitate agile movement and quick reaction or thinking, with a unique body shape to fit tasks and perform diverse physiological functions. In this work, Liu et al were inspired by the fascinating idea of biomimicry to develop multifunctional artificial muscles for smart applications.

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