11:00 AM - SB01.03.03
On-Demand Paper Biobatteries Activated by Human Body Fluids
Mya Landers1,Seokheun Choi1
Binghamton University, The State University of New York1
With the growing demand for point-of-care (POC) and in-field diagnostic testing, paper attracts significant attention as a substrate for simple, low-cost, and disposable analytical devices. A porous, hydrophilic network of intertwined cellulose fibers promotes excellent mechanical, dielectrical and fluidic properties in paper. These properties mean microfluidic assays and electronic/mechanical components can be built into paper, offering the transformative potential of generating important function for POC diagnostic devices. Recent advances in paperfluidic and papertronic technologies offer more decentralized diagnostic analyses with portability, automation, and the capacity to produce test results in shorter times at a reduced cost. However, there has been a significant challenge in realizing a truly stand-alone and self-sustainable diagnostic platform that does not rely on a competent laboratory service or smartphone’s built-in functions. The key challenge is to develop a miniaturized on-chip power source for those paper-based POC devices in a more effective and efficient way. Power autonomy is one of the most critical requirements for the devices so they can work independently and self-sustainably in limited-resource and remote regions, where a stable electrical supply is not available. Even standard batteries are not suitable in those areas because of their cost, incompatibility with paper, and potential danger to the environment. Smartphone built-in batteries are not always available. Also, conventional energy harvesting technologies (e.g. solar, thermal, mechanical, chemical energy) are too overqualified and expensive as a power source for single-use, disposable POC tests, which require relatively small power consumption for only a couple of minutes. What is needed is a low-cost, disposable, and eco-friendly micro-power source that can be easily integrated with paper-based devices and be readily activated even in those challenging field conditions.
Here we provide a realistic and accessible solution as a novel power source that can enable a self-powered paper-based diagnostic test for anyone, anywhere, and anytime. The work creates a paper-based microbial fuel cell (MFC) device that is pre-inoculated with Bacillus subtilis endospores and can be activated with a drop of human body fluids, such as sweat or saliva. B. subtilis endospores are a resilient, desiccation-resistant state of the bacteria that can develop in a nutrient-deficient environment. These endospores are pre-loaded into the anode of the device and begin germination and electricity generation once nutrients become available. Dropping bodily fluids onto the device’s inlet introduces these nutrients to the endospores and activates the biobattery. The design consists of several individual MFC units that can be easily connected through a simple folding mechanism to achieve a higher output power.
Since they are low-cost, fast-acting, and disposable, paper-based MFCs have shown potential for applications in powering a variety of low-power, POC diagnostic tools, especially in resource-limited environments that lack dependable access to other forms of power. Conventional MFC operation often requires exoelectrogen-containing or nutrient-rich water from the environment to be applied to the MFC for activation, but access to such a water source may not always be available. Using bodily fluids to activate the device allows for it to be readily used even in dry climates without access to nutrient-rich environmental water. Since local bacteria may also be incapable of generating electricity, some previous MFC devices have included pre-inoculated, lyophilized exoelectrogens, but lyophilized bacteria have been shown to suffer from significant performance decline over time during storage. Using dehydrated B. subtilis endospores instead extends the durability and shelf-life of the MFC, while still allowing for rapid, on-demand electricity generation once activated.