Biodegradable Supercapacitor with Interdigitated Electrodes
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Solution Overview
Problem
Conventional supercapacitors are too large for in vivo applications and lack biocompatibility and biodegradability, making them unsuitable for miniaturized, implantable bioelectronics and biosensors that require flexible, sustainable, and environmentally benign energy storage solutions.
Innovation Solution
A biocompatible and biodegradable supercapacitor system using a flexible silk protein substrate with biocompatible conductive ink and gel electrolyte, comprising sericin protein photoresist, PEDOT:PSS, and reduced graphene oxide, fabricated through a sustainable, water-based photolithography process at room temperature, eliminating the need for metals and organic solvents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional supercapacitor materials and structures are used, then energy storage performance is achieved, but device size becomes too large for in vivo applications
Solution Approach 1:
The supercapacitor is segmented into multiple interdigitated microelectrode fingers arranged in alternating pattern, where each finger acts as an independent electrode. This segmentation increases the effective electrode surface area within a compact footprint, enabling high energy storage capacity in a miniaturized device suitable for implantable applications
Solution Approach 2:
The design transitions from planar 2D electrodes to three-dimensional interdigitated finger structures, utilizing vertical stacking and lateral arrangement to maximize electrode surface area within a small volume. This dimensional approach allows high capacitance in a compact form factor
2Reliability
If traditional metallic conductors and organic electrolytes are used, then electrical conductivity is achieved, but biocompatibility and biodegradability are compromised
Solution Approach 1:
The conductivity mechanism is changed from metallic electron conduction to ionic conduction through gel electrolyte and proton conduction through PEDOT:PSS conductive polymer. This parameter change enables biocompatible and biodegradable materials to achieve sufficient electrical conductivity for supercapacitor operation
Solution Approach 2:
The device uses composite materials including PEDOT:PSS conductive polymer combined with gel electrolyte, and biodegradable metal alloys. These composites provide both the required electrical conductivity and biocompatibility, with the polymer-gel interface enabling efficient ion-to-electron charge transfer
3Strength
If non-biodegradable materials are used for structural support, then mechanical strength is achieved, but the device requires additional extractive surgery
Solution Approach 1:
The mechanical strength mechanism is changed from permanent structural support to time-dependent degradation. The biodegradable materials are engineered to maintain structural integrity during device operation, then progressively degrade and resorb by the body over time, eliminating the need for surgical removal
Solution Approach 2:
The supercapacitor is designed as a transient implantable device with biodegradable components that fulfill their function temporarily and then safely degrade in the body. This disposable approach eliminates long-term foreign body presence and required removal surgery
4Volume of moving object
If miniaturization is pursued for in vivo applications, then device size is reduced, but capacitance performance decreases
Solution Approach 1:
The electrode structure is segmented into multiple thin interdigitated fingers, creating numerous electrode-electrolyte interfaces within a small volume. This segmentation dramatically increases the effective surface area for charge storage without increasing device footprint
Solution Approach 2:
The device utilizes porous structures including porous substrate and porous conductive polymer layers, which provide high surface area-to-volume ratio. The porous architecture enables increased electrode surface area for capacitance while maintaining compact device dimensions
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system achieves high specific capacitance, cycling stability, and mechanical flexibility, with the ability to be completely biodegraded within a month, making it suitable for implantable bioelectronics and biosensors.
Implementation Method 1
Gel electrolytes are used as electrode separators and ion conductors
Implementation Method 2
The electrodes are usually interfaced with metallic conductors to and for transport of charges
Implementation Method 3
patterning of said biocompatible conductive ink is performed using photolithography
Data Source
AI summary
Provided herein is biodegradable supercapacitor system comprising a protein based flexible thin film substrate, patterned electrodes formed from a biocompatible conductive ink, and biocompatible gel electrolyte. Methods of making the supercapacitor system are also provided.