Minteer is seeking to create a sustainable fuel cell to power up common devices that typically use batteries. This is what she had to say in a recent on-campus interview:
USTAR: Overall, what are the different kinds of batteries people use?
Minteer: You break down batteries into three different types. One is a primary battery that is disposed after use because the chemistry can only occur in one direction. The second is a rechargeable battery with chemistry that can occur in both directions. And finally there are fuel cells, which we consider as hybrid batteries, because you do not plug them in to recharge them, you just continue to add more fuel (i.e. refuel them).
USTAR: Talk about traditional batteries.
Minteer: Traditional batteries are typically metallic batteries. These batteries contain metal that we typically mine, so they are not fabricated from renewable resources. Traditional batteries convert the chemical energy in the metal into electrical energy. However, this is not a sustainable process because we only have so much metal on earth and these batteries are not biodegradable.
The batteries we have now in the market contain toxic materials and unfortunately in the U.S., many people throw them away in landfills, instead of recycling them. So we are ending up with these metals and toxins in our landfills, which can contaminate our water supply, etc.
USTAR: What is a bio-inspired battery?
Minteer: In order to develop a sustainable solution, there needs to be an alternative strategy for energy conversion other than metals. In my research group, we have studied the chemical reaction of metabolism.
If you look at any living system, for example the human body, where you consume food and energy conversion happens, this energy conversion gives you the energy needed to walk around and do your daily activities. A bio-inspired battery captures this bio-inspired energy conversion strategy of the living cells and places it in an electrical energy storage device for use.
USTAR: What is an enzymatic biofuel cell?
Minteer: An enzymatic battery is a type of biofuel cell or bio-battery. Enzymes are proteins from living cells that catalyze reactions. In the Minteer group, we use enzymes to catalyze the reaction that converts chemical energy to electrical energy. These are the same enzymes that are responsible for metabolism of food in the living cell. My lab makes all three types of batteries with enzymes. We make primary bio-batteries, rechargeable bio-batteries, and we make bio-fuel cells.
USTAR: How close are we to creating a bio-inspired battery?
Minteer: Close is an interesting term because that depends on what you are thinking about. Disposable batteries, for example, are not smart batteries. It is simply the chemical components that are put together. There is no management of temperature or current running through these systems. We can make batteries like that today.
If we want to make a bio-inspired battery for a cell phone, laptop or a hybrid car and improve upon existing technology, we need to develop smart batteries. Smart batteries have electronic systems to handle electrical power and temperature management. And those systems are much more complex and have a lot more engineering in them. So developing those kinds of batteries are a longer scale project. We are more in the 5-10 year range for smart batteries, because of the engineering issues.
USTAR: What are the current hurdles you are experiencing?
Minteer: There are several. Every time you go from one type of battery to a different type of battery, you are re-engineering an entirely new battery technology. They are very different systems, so you are re-engineering the battery system frequently.
Our biggest hurdle is the perception people have on the word “bio.” When you talk about bio-batteries, people think you are going to implant the battery into the human body. That means that they only think about fuels that would be present in the body (i.e. blood glucose). Then, they stop thinking about how important it is to have a high-density fuel, because the body carries a limitless amount of glucose (i.e. glucose is always running through your blood system). So it is not a self-contained battery like we are creating, and the implantable system wouldn’t need to consider energy density. However, it you are making a self-contained battery, then energy density is critical.
USTAR: What are the commercialization possibilities?
Minteer: Anything that you can think of that requires batteries is a possible application and a commercialization possibility.
USTAR: What was your inspiration for this bio-battery?
Minteer: It is kind of interesting, because I actually have no biological background. The last time I took a biology class was in high school. I worked on hydrogen/ oxygen fuel cells during my graduate work. When I became a faculty member, I actually went away from energy applications and looked at more analytical chemistry applications of electrochemistry, sensing and situations where you might be able to use electrochemistry to analyze biological components. I started building some collaboration with the medical school at my previous institution [St. Louis University], and I started realizing there is a lot of energy in biological fuels and that biological systems may be able to teach us very important lessons about energy conversion.
Consequently, I ended up going back to fuel cells and realizing biology should be able to teach us about how to improve the efficiency of the system. Then, the more I learned I was able to apply it to making a bio-battery system. However, I am learning it is far more complex then we first envisioned it, but solving these complex problems is exciting.
USTAR: We hear about “biomimicry” - the emulation of Nature’s models and processes to solve human problems. Would you consider your research to be inspired by biomimicry?
Minteer: Early on we were taking biological components from biological entities. We were then putting them on electrode surfaces and now we are forming more biomimics. It is important we understand the biological identities, to understand function effectively, but after that, we can move on to biomimicry.
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