Together, the scientists are developing technologies that leverage the unique properties of bacterial magnetosomes– biologically-derived nanoparticles that have a number of superior properties that include high chemical purity, low toxicity, a high degree of crystallographic perfection and permanent magnetization.

Mission Focused

Knowing that the warfighter is routinely burdened with the weight of electronic devices designed for communication, agent threat detection and other field purposes, Betts and Calm considered the idea of using magnetosomes to develop the next generation of lightweight electronic devices.

“A lot of threat agent detecting sensors are going paper-based because they are logistically easier to use,” Calm said. “Chemical sensors can be bulky and require power to operate. Energy sources, even triple “A” batteries, add weight to the warfighter’s pack which is a logistical challenge many researchers are seeking to overcome.”

“It’s weight. It’s logistics. It’s all of the above,” added Betts. “Our thinking was to help make the power sources used in remote or field-forward sensor applications more paper-based, bringing the idea of lightweight – perhaps even disposable – electronics to the forefront of research.”

“We began to think; so how are we going to come up with things that are lighter and cheaper?” Calm said.

The Research

Participating in the Center’s Biological Engineering for Applied Materials Solutions (BEAMS) nanocellulose competition last summer led Calm and Betts to speculate how they could leverage what they had learned from the competition for their current work with magnetosomes.

“That’s where we started brainstorming and working with the idea of magnetically infused paper,” Calm said. “One crazy thought led to another,” she said, ending with Betts coming up with the idea of a biologically-derived transformer core.

“The idea is that you could make transformers really, really small, even as thin as a piece of paper,” Calm reiterated.

“It’s very out there. Very Star Trek,” Betts chimes in.

“But in theory, it will work.” Calm finishes.

The first step on their futuristic journey required proof that the team could coax the magnetotatic bacteria M. gryphiswaldense to produce magnetite nanoparticles.

Long strings of membrane-bound magnetite nanoparticles called magnetosomes are produced within the bacteria when they are deprived of oxygen. In their search for oxygen, the strings of magnetosomes serve as a kind of internal compass that lets them navigate to a more oxygen-rich environment using the Earth’s geomagnetic field.

It takes countless strings of magnetosomes to further Calm’s and Betts’ goal. Growing the bacteria on a bigger scale has been successful, with 20 liter batches grown by colleague Michael Kim, Ph.D., at the large-scale fermentation facility at the Center’s biotechnology laboratory.

“We are going to grow our non-conductive nanocellulose layer,” Calm explained, “and then we’ll overlay it with a culture of magnetic bacterial magnetosomes that will be guided with powerful magnets into a pattern.”

The resulting pellicle or thin film will then be processed, dried, and cut and/or folded into a transformer core comprised of paper-thin alternating conductive and non-conductive layers.

“We’ll then test the transformer by measuring the output of the circuits,” Calm said. “It should increase the electrical output compared to our control that would be wrapped with just plain nanocellulose layers without the magnetosomes in between.”

“The dream is that with these kinds of living materials, we’re changing the paradigm,” Betts said.

“It’s not a metal. It’s something that’s alive and maybe these could, down the line, work into materials that could self-repair.”

Currently, the medical field is investigating magnetosomes for applications such as medical imaging, drug delivery and cancer research.

“This is just one strain of bacteria that we are working with,” Calm said. “There are many. They come in different shapes and sizes and sequester different metals like gold and silver. Years down the line you may want a nanoparticle that’s a certain size or a certain shape and a certain metal.”

Versatility

In addition, because biologically-derived magnetosomes are produce in a pearl-like strand, they have unique characteristics over synthetic nanoparticles that generally produce individually, not in strands.

Because magnetosomes also have membranes, researchers can genetically engineer them or chemically attach enzymes to make the natural nanoparticle do even more.

Moving Forward

If their circuit output test proves successful, the two will next try to use the transformer to create paper-based circuitry. But before that can happen, they will need more funding.

Already, one major defense contractor has contacted the pair to discuss ways to grow the magnetosomes faster. Betts and Calm are eager to continue their research.

“It’ll be really interesting because it is a proof of concept project that will hopefully spark the interest of other scientists who see the work that we’re doing and will want to collaborate,” Calm said.

Given that the convergence of material science and biological engineering has seen significant interest and investment by the Department of Defense, Calm and Betts are hoping their efforts will help towards the development of never-before-seen materials that are able to meet the unique requirements and challenges of the defense environment of the future.