These hydrogels can generate voltages when touched, but scientists did not clearly understand how — until a team of researchers at UBC devised a unique experiment, published today in Science.

“How hydrogel sensors work is they produce voltages and currents in reaction to stimuli, such as pressure or touch — what we are calling a piezoionic effect. But we didn’t know exactly how these voltages are produced,” said the study’s lead author Yuta Dobashi, who started the work as part of his master’s in biomedical engineering at UBC.

Working under the supervision of UBC researcher Dr. John Madden, Dobashi devised hydrogel sensors containing salts with positive and negative ions of different sizes. He and collaborators in UBC’s physics and chemistry departments applied magnetic fields to track precisely how the ions moved when pressure was applied to the sensor.

“When pressure is applied to the gel, that pressure spreads out the ions in the liquid at different speeds, creating an electrical signal. Positive ions, which tend to be smaller, move faster than larger, negative ions. This results in an uneven ion distribution which creates an electric field, which is what makes a piezoionic sensor work.”

The researchers say this new knowledge confirms that hydrogels work in a similar way to how humans detect pressure, which is also through moving ions in response to pressure, inspiring potential new applications for ionic skins.

“The obvious application is creating sensors that interact directly with cells and the nervous system, since the voltages, currents and response times are like those across cell membranes,” says Dr. Madden, an electrical and computer engineering professor in UBC’s faculty of applied science. “When we connect our sensor to a nerve, it produces a signal in the nerve. The nerve, in turn, activates muscle contraction.”

“You can imagine a prosthetic arm covered in an ionic skin. The skin senses an object through touch or pressure, conveys that information through the nerves to the brain, and the brain then activates the motors required to lift or hold the object. With further development of the sensor skin and interfaces with nerves, this bionic interface is conceivable.”

Another application is a soft hydrogel sensor worn on the skin that can monitor a patient’s vital signs while being totally unobtrusive and generating its own power.

Dobashi, who’s currently completing his PhD work at the University of Toronto, is keen to continue working on ionic technologies after he graduates.

“We can imagine a future where jelly-like ‘iontronics’ are used for body implants. Artificial joints can be implanted, without fear of rejection inside the human body. Ionic devices can be used as part of artificial knee cartilage, adding a smart sensing element. A piezoionic gel implant might release drugs based on how much pressure it senses, for example.”

Dr. Madden added that the market for smart skins is estimated at $4.5 billion in 2019 and it continues to grow. “Smart skins can be integrated into clothing or placed directly on the skin, and ionic skins are one of the technologies that can further that growth.”

The research includes contributions from UBC chemistry PhD graduate Yael Petel and Carl Michal, UBC professor of physics, who used the interaction between strong magnetic fields and the nuclear spins of ions to track ion movements within the hydrogels. Cédric Plesse, Giao Nguyen and Frédéric Vidal at CY Cergy Paris University in France helped develop a new theory on how the charge and voltage are generated in the hydrogels.

This finding is unexpected because the plate tectonic regime of our planet progressively recycles crustal material via large-scale mantle convection at much smaller time scales. Therefore, it has been assumed that vestiges of early geological processes on Earth can only be found as analogues, on other terrestrial planets (Mercury, Venus, and Mars), asteroids, or the Moon. However, according to their study ‘Long-term preservation of Hadean protocrust in Earth’s mantle’, which has recently appeared in the Proceedings of the National Academy of Sciences (PNAS), magmatic rocks that erupted throughout Earth’s history can still carry signatures that provide detailed information about the nature of the first crust, its long-term preservation in a graveyard in the lower-most mantle, and its resurrection via younger volcanism.

For their study, the geologists investigated up to 3.55 billion years old rocks from southern Africa. The analysis of these rocks revealed small anomalies in the isotope composition of the element tungsten (W). The origin of these isotope anomalies, namely the relative abundance of ¹⁸²W, relates to geological processes that must have occurred immediately after the formation of the Earth more than 4.5 billion years ago.

Model calculations by the authors show that the observed ¹⁸²W isotope patterns are best explained by the recycling of Earth’s earliest crust into mantle material that ascends via plumes from the lower mantle to generate lavas erupting at Earth’s surface. Intriguingly, the study shows that similar isotope patterns can be observed in distinct types of modern volcanic rocks (ocean island basalts), which demonstrates that Earth’s earliest crust is still buried in the lowermost mantle.

‘We assume that the lower layers of the crust — or the roots of the primordial continents — became heavier than their surroundings due to a geological maturation process and therefore sank into the Earth’s underlying mantle. Similar to a lava lamp,’ geochemist Dr Jonas Tusch from the University of Cologne’s Institute of Geology and Mineralogy remarked. ‘This fascinating insight provides a geochemical fingerprint of the young Earth, allowing us to better understand how large continents formed over the history of our planet. It also explains how our current, oxygen-rich atmosphere evolved — setting the stage for the origin of complex life,’ Dr Elis Hoffmann of Freie Universität Berlin added.

The geochemical fingerprint of the early Earth can also be compared with findings about other planets obtained during space missions. For example, data from Mars missions and studies of Martian meteorites show that Mars still has a very old surface due to the lack of plate tectonics, and that its composition may correspond to that of the young Earth.

Story Source:

Materials provided by University of Cologne. Note: Content may be edited for style and length.

Some people with COVID-19 experience the disease more severely than others. Previous research has identified certain variants in specific human genes that are associated with a person experiencing more severe COVID-19. Some of these variants may also be associated with other medical conditions that may already be well understood; identifying these shared variants could improve understanding of COVID-19 and illuminate potential new paths for treatment.

To identify shared variants, Verma and colleagues used an unprecedented dataset of genotypic information linked to electronic health record data (EHR) for more than 650,000 U.S. veterans. They conducted a type of analysis known as a phenome-wide association study (PheWAS) to examine links between variants often found in Veterans who experienced severe COVID-19 and variants associated with a broad selection of medical conditions.

The analysis revealed that certain variants associated with COVID-19 are also associated with known risk factors for COVID-19. Particularly strong links were found for variants associated with venous embolism and thrombosis, as well as type 2 diabetes and ischemic heart disease — two known COVID-19 risk factors.

The analysis also found genetic links between severe COVID-19 and neutropenia for Veterans of African and Hispanic ancestry; these links did not appear for those of European ancestry.

Among respiratory conditions, idiopathic pulmonary fibrosis and chronic alveolar lung disease shared genetic links with severe COVID-19, but other respiratory infections and chronic obstructive pulmonary disease (COPD) did not. Some variants associated with severe COVID-19 were also associated with reduced risk of autoimmune conditions, such as psoriasis and lupus. These findings highlight the need to carefully weigh various aspects of the immune system when developing new treatments.

Despite some limitations of the PheWAS method, these findings could help deepen understanding of COVID-19 and guide development of new treatments.

Verma concludes, “The study demonstrates the value and impact of large biobanks linking genetic variations with EHR data in public health response to the current and future pandemics. MVP is one of the most diverse cohorts in the US. We had a unique opportunity to scan thousands of conditions documented before the COVID-19 pandemic. We gained insights into the genetic architecture of COVID-19 risk factors and disease complication.”

“One thing that stood out to us was the high number of immune-mediated conditions that shared genetic architecture with severe manifestations of COVID-19,” coauthor Katherine Liao adds. “The nature of the associations brought to light how the SARS-CoV2 virus pushes on a pressure point in the human immune system and its constant balancing act of fighting infection while maintaining enough control so that it does not also become an autoimmune process, attacking self.”

Story Source:

Materials provided by PLOS. Note: Content may be edited for style and length.