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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Mucoadhesive and Rheological Studies on the Co-Hydrogel Systems of Poly(Ethylene Glycol) Copolymers with Fluoroalkyl and Poly(Acrylic Acid)
A self-assembled co-hydrogel system with sol-gel two-phase coexistence and mucoadhesive properties was developed based on the combined properties of fluoroalkyl double-ended poly(ethylene glycol) (Rf-PEG-Rf) and poly(acrylic acid) (PAA), respectively. We have synthesized an Rf-PEG-g-PAA (where g denotes grafted) copolymer and integrated it into the Rf-PEG-Rf physically cross-linked micellar network to form a co-hydrogel system. Tensile strengths between the co-hydrogel surfaces and two different sets of mucosal surfaces were acquired. One mucosal surface was made of porcine stomach mucin Type II, while the other one is a pig small intestine. The experimental results show that the largest maximum detachment stresses (MDSs) were obtained when the Rf-PEG-g-PAA’s weight percent in the dehydrated polymer mixture is ~15%. Tensile experiments also found that MDSs are greater in acidic conditions (pH = 4–5) (123.3 g/cm2 for the artificial mucus, and 43.0 g/cm2 for pig small intestine) and basic conditions (pH = 10.6) (126.9 g/cm2, and 44.6 g.cm2, respectively) than in neutral pH (45.4 g/cm2, and 30.7 g.cm2, respectively). Results of the rheological analyses using shear strain amplitude sweep and frequency sweep reveal that the Rf-PEG-g-PAA was physically integrated into the Rf-PEG-Rf micellar network, and the co-hydrogels remain physically cross-linked in three-dimensional micellar networks with long-term physical dispersion stability. Therefore, the co-hydrogel system is promising for drug delivery applications on mucosal surfaces.
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- Award ID(s):
- 1727015
- NSF-PAR ID:
- 10308919
- Date Published:
- Journal Name:
- Polymers
- Volume:
- 13
- Issue:
- 12
- ISSN:
- 2073-4360
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.3390/polym13121956
