PCB Air-Breathing Aperture Layout for Biofuel Cell Oxygen Supply
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Solution Overview
Problem
Existing biofuel cells face challenges in maintaining sufficient oxygen supply and liquid retention, especially when integrated with printed circuit boards (PCBs), which can block air-breathing apertures and reduce device performance.
Innovation Solution
The development of an electronic 'sandwich' device comprising a biofuel cell and a PCB with an air-breathing aperture, where the PCB aperture is aligned opposite the biofuel cell's external layer air-breathing aperture, ensuring a clear flux of air to the cathode while using a gas diffusion layer and liquid reservoir to maintain liquid levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a membrane is implemented to support oxygen flux whilst limiting liquid loss, then oxygen supply is improved, but device complexity increases
Solution Approach 1:
The Gas Diffusion Layer (GDL) performs multiple functions simultaneously: it serves as an oxygen flux pathway, a liquid retention barrier, and an electrical current collector. This multi-functionality resolves the contradiction by improving oxygen supply without adding separate components, thus avoiding increased device complexity.
Solution Approach 2:
The GDL utilizes its porous structure to selectively transport oxygen while retaining liquid through capillary pressure. The porous material inherently provides the membrane function needed for oxygen supply without requiring an additional separate membrane component, thereby resolving the contradiction between oxygen flux and device complexity.
2Length of stationary object
If the device thickness is reduced to minimize overall volume, then device miniaturization is achieved, but the surface area available for air-breathing aperture is reduced
Solution Approach 1:
The invention transitions from a single-sided air-breathing design to a dual-sided configuration where the PCB provides an air-breathing aperture from the opposite side of the biofuel cell. This dimensional change allows both thinness and sufficient aperture area to be achieved simultaneously, as air can enter through both surfaces of the device.
Solution Approach 2:
The air-breathing function is segmented between two separate components: the biofuel cell's external layer aperture and the PCB's aperture. This segmentation allows each component to be optimized independently, enabling the biofuel cell to remain thin while the PCB provides additional aperture area from the opposite side.
3Reliability
If a liquid reservoir is provided to maintain wetting of interfaces, then liquid retention is improved, but device volume increases
Solution Approach 1:
The GDL's hydrophobic properties enable it to self-regulate liquid retention through capillary pressure without requiring an external reservoir. The porous structure automatically retains sufficient liquid for ionic transport while allowing oxygen flux, providing self-service liquid management that avoids increasing device volume.
Solution Approach 2:
The porous GDL structure provides inherent liquid retention through capillary forces, eliminating the need for a separate liquid reservoir. The porous material's surface tension properties automatically maintain the liquid film needed for ionic species transport, resolving the contradiction between liquid retention and device volume.
4Strength
If the PCB blocks the air-breathing aperture, then structural support is provided, but oxygen flux to the cathode is reduced
Solution Approach 1:
The solution moves from a single-sided air-breathing design to a dual-sided configuration where air enters through both the biofuel cell's external layer and the PCB's aperture from the opposite side. This dimensional change allows the PCB to provide structural support while simultaneously providing an additional oxygen flux pathway, resolving the contradiction between support and oxygen supply.
Solution Approach 2:
The oxygen flux function is segmented between two pathways: the external layer aperture and the PCB aperture. This segmentation allows the PCB to fulfill its structural support role while also contributing to oxygen flux, eliminating the trade-off between support and oxygen supply.
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
This configuration enhances cathodic current density by approximately 2.5-fold, improving overall biofuel cell performance by maximizing oxygen flux and liquid retention while minimizing device thickness.
Implementation Method 1
Gas diffusion layers (GDLs), made often of carbon, are frequently employed as they can double as an electrical current collector. Carbon-based GDLs are porous materials composed of a dense array of carbon fibers, which may also be modified with other carbon micro-/nano-structures. This structure provides intrinsic hydrophobicity, reducing loss of liquid
Implementation Method 2
This structure provides intrinsic hydrophobicity, reducing loss of liquid, but may also be further treated (e.g., inclusion of PTFE) to increase hydrophobicity
Implementation Method 3
the air-breathing aperture formed into the PCB is opposite the external layer air-breathing aperture, the biofuel cell being attached to the PCB
Implementation Method 4
provide a mechanism to maintain wetting of the interfaces
Data Source
AI summary
An electronic device comprising a biofuel cell and a printed circuit board (PCB) with an air-breathing aperture is disclosed, the biofuel cell comprising an external layer air-breathing aperture (through GDL), the electronic device being characterized in that the air-breathing aperture formed into the PCB is opposite the external layer air-breathing aperture, the biofuel cell being attached to the PCB.