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Abstract Functioning ingestible capsules offer tremendous promise for a plethora of diagnostic and therapeutic applications. However, the absence of realistic and practical power solutions has greatly hindered the development of ingestible electronics. Microbial fuel cells (MFCs) hold great potential as power sources for such devices as the small intestinal environment maintains a steady internal temperature and a neutral pH. Those conditions and the constant supply of nutrient‐rich organics are a perfect environment to generate long‐lasting power. Although previous small‐scale MFCs have demonstrated many promising applications, little is known about the potential for generating power in the human gut environment. Here, this work reports the design and operation of a microbial biobattery capsule for ingestible applications. DormantBacillus subtilisendospores are a storable anodic biocatalyst that will provide on‐demand power when revived by nutrient‐rich intestinal fluids. A conductive, porous, poly(3,4‐ethylenedioxythiophene) polystyrene sulfonate hydrogel anode enables superior electrical performance in what is the world's smallest MFC. Moreover, an oxygen‐rich cathode maintains its effective cathodic capability even in the oxygen‐deficit intestinal environment. As a proof‐of‐concept demonstration in stimulated intestinal fluid, the biobattery capsule produces a current density of 470 µA cm−2and a power density of 98 µW cm−2, ensuring its practical efficacy as a novel and sole power source for ingestible applications in the small intestine.
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BIOPOWER-IN-GUT: AN INGESTIBLE BACTERIA-POWERED BATTERY CAPSULE
We report an ingestible, millimeter-sized microbial fuel cell (MFC) capsule that can provide a realistic and practical power solution for ingestible electronics. The capsule integrates a pH-sensitive enteric membrane, a germinant-containing layer, and a microfluidic hydrogel-based anodic channel pre-inoculated with Bacillus subtilis spores as dormant biocatalysts, which are directly connected to an integrated MFC. When the pH-sensitive membrane dissolves in a designated gut location with a specific pH, the hydrophilic hydrogel in the anodic channel absorb the gut fluids washing the germinant to trigger the spore germination and generate microbial metabolic electricity in our world’s smallest MFC. When the capsule is designed to work in the human intestine, it generates electricity only in the neutral pH solution achieving maximum power and current densities of 64μW/cm2 and 435 μA/cm2, respectively, which are substantially higher than the other energy harvesting techniques.
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- PAR ID:
- 10376400
- Date Published:
- Journal Name:
- Technical digest SolidState Sensor Actuator and Microsystems Workshop
- ISSN:
- 1539-204X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Accepted Manuscript1.0
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