A thimbleful of soil can contain a universe of microorganisms, up to 10 billion by some estimates. Now a group of researchers in Bath, United Kingdom, are building prototype technologies that harvest electrons exhaled by some micro-species.

The idea is to power up low-yield sensors and switches, and perhaps help farmers digitally optimize crop yields to meet increasing demand and more and more stressful growing conditions. There could be other tasks, too, that might make use of a plant-and-forget, low-yield power source—such as monitoring canals for illegal waste dumping.

The research started small, based out of the University of Bath, with field-testing in a Brazilian primary school classroom and a green pond near it—just before the onset of the pandemic.

“We had no idea what the surroundings would be. We just packed the equipment we needed and went,” says Jakub Dziegielowski, a University of Bath, U.K. chemical engineering Ph.D. student. “And the pond was right by the school—it was definitely polluted, very green, with living creatures in it, and definitely not something I’d feel comfortable drinking from. So it got the job done.”

The experiments they did along with kids from the school and Brazilian researchers that summer of 2019 were aimed at running water purifiers. It did so. However, it also wasn’t very efficient, compared to, say, a solar panel.

So work has moved on in the Bath labs: in the next weeks, Dziegielowski will both turn 29 and graduate with his doctorate. And he, along with two other University of Bath advisors and colleagues recently launched a spinoff company—it’s called Bactery—to perfect a prototype for a network of soil microbial fuel cells for use in agriculture.

A microbial fuel cell is a kind of power plant that converts chemical energy stored in organic molecules into electrical energy, using microbes as a catalyst. It’s more often used to refer to liquid-based systems, Dziegielowski says. Organics from wastewater serve as the energy source, and the liquid stream mixes past the electrodes.

A soil microbial fuel cell, however, has one of its electrodes—the anode, which absorbs electrons—in the dirt. The other electrode, the cathode, is exposed to air. Batteries work because ions move through an electrolyte between electrodes to complete a circuit. In this case, the soil itself acts as the electrolyte—as well as source of the catalytic microbes, and as the source of the fuel.

The Bath, U.K.-based startup Bactery has developed a set up fuel cells powered by microbes in the soil—with, in the prototype pictured here, graphite mats as electrodes. University of Bath

Fields full of Watts

In a primary school in the fishing village of Icapuí on Brazil’s semi-arid northeastern coast, the group made use of basic components: graphite felt mats acting as electrodes, and nylon pegs to maintain spacing and alignment between them. (Bactery is now developing new kinds of casing.)

By setting up the cells in a parallel matrix, the Icapuí setup could generate 38 milliwatts per square meter. In work since, the Bath group’s been able to reach 200 milliwatts per square meter.

Electroactive bacteria—also called exoelectrogens or electricigens—take in soluble iron or acids or sugar and exhale electrons. There are dozens of species of microbes that can do this, including bacteria belonging to genera such as Geobacter and Shewanella. There are many others.

But 200 milliwatts per square meter is not a lot of juice: enough to charge a mobile phone, maybe, or keep an LED nightlight going—or, perhaps, serve as a power source for sensors or irrigation switches. “As in so many things, it comes down to the economics,” says Bruce Logan, an environmental engineer at Penn State who wrote a 2007 book, Microbial Fuel Cells.

A decade ago Palo Alto engineers launched the MudWatt, a self-contained kit that could light a small LED. It’s mostly marketed as a school science project. But even now, some 760 million people do not have reliable access to electricity. “In remote areas, soil microbial fuel cells with higher conversion and power management efficiencies would fare better than batteries,” says Sheela Berchmans, a retired chief scientist of the Central Electrochemical Research Institute in Tamil Nadu, India.

Korneel Rabaey, professor in the department of biotechnology at the University of Ghent, in Belgium, says electrochemical micro-power sources—a category that now includes the Bactery battery—is gaining buzz in resource recovery, for uses such as extracting pollutants from wastewater, with electricity as a byproduct. “You can think of many applications that don’t require a lot of power,” he says, “But where sensors are important.”

Cochlear implants—the neural prosthetic cousins of standard hearing aids—can be a tremendous boon for people with profound hearing loss. But many would-be users are turned off by the device’s cumbersome external hardware, which must be worn to process signals passing through the implant. So researchers have been working to make a cochlear implant that sits entirely inside the ear, to restore speech and sound perception without the lifestyle restrictions imposed by current devices.

A new biocompatible microphone offers a bridge to such fully internal cochlear implants. About the size of a grain of rice, the microphone is made from a flexible piezoelectric material that directly measures the sound-induced motion of the eardrum. The tiny microphone’s sensitivity matches that of today’s best external hearing aids.

Cochlear implants create a novel pathway for sounds to reach the brain. An external microphone and processor, worn behind the ear or on the scalp, collect and translate incoming sounds into electrical signals, which get transmitted to an electrode that’s surgically implanted in the cochlea, deep within the inner ear. There, the electrical signals directly stimulate the auditory nerve, sending information to the brain to interpret as sound.

But, says Hideko Heidi Nakajima, an associate professor of otolaryngology at Harvard Medical School and Massachusetts Eye and Ear, “people don’t like the external hardware.” They can’t wear it while sleeping, or while swimming or doing many other forms of exercise, and so many potential candidates forgo the device altogether. What’s more, incoming sound goes directly into the microphone and bypasses the outer ear, which would otherwise perform the key functions of amplifying sound and filtering noise. “Now the big idea is instead to get everything—processor, battery, microphone—inside the ear,” says Nakajima. But even in clinical trials of fully internal designs, the microphone’s sensitivity—or lack thereof—has remained a roadblock.

Nakajima, along with colleagues from MIT, Harvard, and Columbia University, fabricated a cantilever microphone that senses the motion of a bone attached behind the eardrum called the umbo. Sound entering the ear canal causes the umbo to vibrate unidirectionally, with a displacement 10 times as great as other nearby bones. The tip of the “UmboMic” touches the umbo, and the umbo’s movements flex the material and produce an electrical charge through the piezoelectric effect. These electrical signals can then be processed and transmitted to the auditory nerve. “We’re using what nature gave us, which is the outer ear,” says Nakajima.

Why a cochlear implant needs low-noise, low-power electronics

Making a biocompatible microphone that can detect the eardrum’s minuscule movements isn’t easy, however. Jeff Lang, a professor of electrical engineering at MIT who jointly led the work, points out that only certain materials are tolerated by the human body. Another challenge is shielding the device from internal electronics to reduce noise. And then there’s long-term reliability. “We’d like an implant to last for decades,” says Lang.

In tests of the implantable microphone prototype, a laser beam measures the umbo’s motion, which gets transferred to the sensor tip. JEFF LANG & HEIDI NAKAJIMA

The researchers settled on a triangular design for the 3-by-3-millimeter sensor made from two layers of polyvinylidene fluoride (PVDF), a biocompatible piezoelectric polymer, sandwiched between layers of flexible, electrode-patterned polymer. When the cantilever tip bends, one PVDF layer produces a positive charge and the other produces a negative charge—taking the difference between the two cancels much of the noise. The triangular shape provides the most uniform stress distribution within the bending cantilever, maximizing the displacement it can undergo before it breaks. “The sensor can detect sounds below a quiet whisper,” says Lang.

Emma Wawrzynek, a graduate student at MIT, says that working with PVDF is tricky because it loses its piezoelectric properties at high temperatures, and most fabrication techniques involve heating the sample. “That’s a challenge especially for encapsulation,” which involves encasing the device in a protective layer so it can remain safely in the body, she says. The group had success by gradually depositing titanium and gold onto the PVDF while using a heat sink to cool it. That approach created a shielding layer that protects the charge-sensing electrodes from electromagnetic interference.

The other tool for improving a microphone’s performance is, of course, amplifying the signal. “On the electronics side, a low-noise amp is not necessarily a huge challenge to build if you’re willing to spend extra power,” says Lang. But, according to MIT graduate student John Zhang, cochlear implant manufacturers try to limit power for the entire device to 5 milliwatts, and just 1 mW for the microphone. “The trade-off between noise and power is hard to hit,” Zhang says. He and fellow student Aaron Yeiser developed a custom low-noise, low-power charge amplifier that outperformed commercially available options.

“Our goal was to perform better than or at least equal the performance of high-end capacitative external microphones,” says Nakajima. For leading external hearing-aid microphones, that means sensitivity down to a sound pressure level of 30 decibels—the equivalent of a whisper. In tests of the UmboMic on human cadavers, the researchers implanted the microphone and amplifier near the umbo, input sound through the ear canal, and measured what got sensed. Their device reached 30 decibels over the frequency range from 100 hertz to 6 kilohertz, which is the standard for cochlear implants and hearing aids and covers the frequencies of human speech. “But adding the outer ear’s filtering effects means we’re doing better [than traditional hearing aids], down to 10 dB, especially in speech frequencies,” says Nakajima.

Plenty of testing lies ahead, at the bench and on sheep before an eventual human trial. But if their UmboMic passes muster, the team hopes that it will help more than 1 million people worldwide go about their lives with a new sense of sound.

The work was published on 27 June in the Journal of Micromechanics and Microengineering.

Few correctional facilities in the United States have treatment programs for individuals with opioid use disorder (OUD), despite clear evidence that certain medications reduce the risk of overdose and death. Even in facilities where treatment is available, the COVID-19 pandemic has complicated efforts to provide such care.

The Pew Charitable Trusts sent comments Jan. 4 to the Office of the National Coordinator for Health Information Technology (ONC) and the Centers for Medicare & Medicaid Services (CMS) urging them to support the easy exchange of individuals’ health records through a pair of regulations.

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Simon Saradzhyan writes that the benefits that discontinuing the war on Russia’s terms can generate for defending or advancing Russia’s vital interests will exceed the costs of doing so.

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Renowned singer Chappell Roan has stirred discussions among her fans after she commented on Billboard’s post that stated that she has parted ways with her management team and manager, Nick Bobetsky. She recently made headlines after her name was inducted into the list of candidates who are nominated in the big categories of next year’s […]

The post Why Fans Think Chappell Roan Has Fired Her Manager Nick Bobetsky appeared first on ComingSoon.net - Movie Trailers, TV & Streaming News, and More.

Yellowstone recently started airing part 2 of its fifth season. It resumes the journey of the Dutton’s to protect their ranch triggering high-voltage drama and entertainment. However, the most shocking aspect of the season was the death of the family’s patriarch, John Dutton. So, who killed John Dutton in Yellowstone Season 5? Here is everything […]

The post Yellowstone Season 5: Who Killed John Dutton? Jamie, Sarah or Beth? appeared first on ComingSoon.net - Movie Trailers, TV & Streaming News, and More.

With former U.S. President Donald Trump returning to the White House for a second term, we speak with Pakistani author and columnist Fatima Bhutto. Bhutto is an award-winning author and writes a monthly column for Zeteo on world affairs. She criticizes Kamala Harris’s campaign for relying heavily on celebrity endorsements and vague appeals to “joy” while silencing dissent on Gaza as the Biden administration continues backing Israel. “You don’t need to be a man to practice toxic masculinity, and you don’t need to be white to practice white supremacy,” says Bhutto.

Dutch Palestinian analyst Mouin Rabbani discusses the violence that broke out last week between visiting Israeli soccer fans and pro-Palestinian protesters in Amsterdam. The Dutch authorities made over 60 arrests, and at least five people were hospitalized as a result of the clashes, which local and international leaders were quick to brand as antisemitic, even though observers in Amsterdam have said it was Israeli hooligans who instigated much of the violence. Rabbani says that while it’s common for rival teams’ fans to get into skirmishes, what happened in Amsterdam was different. “What we’re talking about here in Amsterdam is not a clash between the hooligans of two opposing sides, but rather these Israeli thugs attacking people who, in principle, had nothing to do with the game, and then afterwards being confronted by their victims,” Rabbani says.

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