Last fall, Professor Seokheun “Sean” Choi from the Watson College (Binghamton University) and his Bioelectronics and Microsystems Laboratory published their research into an ingestible biobattery activated by the Ph factor of the human intestine. Now, he and PhD student Maryam Rezaie have taken what they learned and incorporated it into new ideas for use outside the body. A new study in the journal Small, which covers nanotechnology, shares the results from using spore-forming bacteria similar to the previous ingestible version to create a device that potentially would still work after 100 years.

“The overall objective is to develop a microbial fuel cell that can be stored for a relatively long period without degradation of biocatalytic activity and also can be rapidly activated by absorbing moisture from the air,” said Choi, a faculty member in the Department of Electrical and Computer Engineering at the Thomas J. Watson College of Engineering and Applied Science.

“We wanted to make these biobatteries for portable, storable and on-demand power generation capabilities,” Choi said. “The problem is, how can we provide the long-term storage of bacteria until used? And if that is possible, then how would you provide on-demand battery activation for rapid and easy power generation? And how would you improve the power?”

The dime-sized fuel cell was sealed with a piece of Kapton tape, a material that can withstand temperatures from -500 to 750 degrees Fahrenheit. When the tape was removed and moisture allowed in, the bacteria mixed with a chemical germinant that encouraged the microbes to produce spores. The energy from that reaction produced enough to power an LED, a digital thermometer or a small clock.

Heat activation of the bacterial spores cut the time to full power from 1 hour to 20 minutes, and increasing the humidity led to higher electrical output. After a week of storage at room temperature, there was only a 2% drop in power generation.

Source: https://www.binghamton.edu/

A fuel cell under the skin that converts blood sugar from the body into electrical energy sounds like science fiction. Yet it works perfectly, as an ETH Zurich research team led by Martin Fussenegger, Professor of Biotechnology and Bioengineering, has shown. In type 1 diabetes, the body does not produce insulin. This means that patients have to obtain the hormone externally to regulate their blood sugar levels. Nowadays, this is mostly done via insulin pumps that are attached directly to the body. These devices, as well as other medical applications such as pacemakers, require a reliable energy supply, which at present is met primarily by power from either single-​use or rechargeable batteries.

Now, a team of researchers led by Martin Fussenegger from the Department of Biosystems Science and Engineering at ETH Zurich in Basel (Switzerland) have put a seemingly futuristic idea into practice. They have developed an implantable fuel cell that uses excess blood sugar (glucose) from tissue to generate electrical energy. The researchers have combined the fuel cell with artificial beta cells developed by their group several years ago. These produce insulin at the touch of a button and effectively lower blood glucose levels much like their natural role models in the pancreas.

“Many people, especially in the Western industrialised nations, consume more carbohydrates than they need in everyday life,” Fussenegger explains. This, he adds, leads to obesity, diabetes and cardiovascular disease. “This gave us the idea of using this excess metabolic energy to produce electricity to power biomedical devices,” he says.

At the heart of the fuel cell is an anode (electrode) made of copper-​based nanoparticles, which Fussenegger’s team created specifically for this application. It consists of copper-​based nanoparticles and splits glucose into gluconic acid and a proton to generate electricity, which sets an electric circuit in motion. Wrapped in a nonwoven fabric and coated with alginate, an algae product approved for medical use, the fuel cell resembles a small tea bag that can be implanted under the skin. The alginate soaks up body fluid and allows glucose to pass from the tissue into the fuel cell within.

Source: https://ethz.ch/

One prospective source of renewable energy is hydrogen gas produced from water with the aid of sunlight. Researchers at Linköping University (LiU) in Sweden have developed a material, nanoporous cubic silicon carbide, that exhibits promising properties to capture solar energy and split water for hydrogen gas production.

Cubic silicon carbide immersed in water

“New sustainable energy systems are needed to meet global energy and environmental challenges, such as increasing carbon dioxide emissions and climate change”, says Jianwu Sun, senior lecturer in the Department of Physics, Chemistry and Biology at Linköping University, who has led the new study that has been published in the journal ACS Nano.

Hydrogen has an energy density three times that of petrol. It can be used to generate electricity using a fuel cell, and hydrogen-fuelled cars are already commercially available. When hydrogen gas is used to produce energy, the only product formed is pure water. In contrast, however, carbon dioxide is created when the hydrogen is produced, since the most commonly used technology used today depends on fossil fuels for the process. Thus, 9-12 tonnes of carbon dioxide are emitted when one tonne of’ hydrogen gas is produced.

Producing hydrogen gas by splitting water molecules with the aid of solar energy is a sustainable approach that could give hydrogen gas using renewable sources without leading to carbon dioxide emissions. A major advantage of this method is the possibility to convert solar energy to fuel that can be stored. “Conventional solar cells produce energy during the daytime, and the energy must either be used immediately, or stored in, for example, batteries. Hydrogen is a promising source of energy that can be stored and transported in the same way as traditional fuels such as petrol and diesel”, says Jianwu Sun.

It is not, however, an easy task to split water using the energy in sunlight to give hydrogen gas. For this to succeed, it is necessary to find cost-efficient materials that have the right properties for the reaction in which water (H₂O) is split into hydrogen (H₂) and oxygen (O₂) through photo-electrolysis. The energy in sunlight that can be used to split water is mostly in the form of ultraviolet radiation and visible light. Therefore, a material is required that can efficiently absorb such radiation to create charges that can be separated and have enough energy to split the water molecules into hydrogen and oxygen gases. Most materials that have been investigated until now are either inefficient in the way they use the energy of visible sunlight (titanium dioxide, TiO₂, for example, absorbs only ultraviolet sunlight), or do not have the properties needed to split water to hydrogen gas (for instance, silicon, Si).

Jianwu Sun’s research group has investigated cubic silicon carbide, 3C-SiC. The scientists have produced a form of cubic silicon carbide that has many extremely small pores. The material, which they call nanoporous 3C-SiC, has promising properties that suggest it can be used to produce hydrogen gas from water using sunlight. The present study has been published in the journal ACS Nano, and in it the researchers show that this new porous material can efficiently trap and harvest ultraviolet and most of the visible sunlight. Furthermore, the porous structure promotes the separation of charges that have the required energy, while the small pores give a larger active surface area. This enhances charge transfer and increases the number of reaction sites, thus further boosting the water splitting efficiency.

“The main result we have shown is that nanoporous cubic silicon carbide has a higher charge-separation efficiency, which makes the splitting of water to hydrogen much better than when using planar silicon carbide”, says Jianwu Sun.

Source: https://liu.se/