Monocrystalline Silicon Fuel Cell with Parallel Trenches
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Solution Overview
Problem
Existing micro fuel cells on silicon substrates face challenges in achieving high energy density and mechanical sturdiness due to the complexity of electrical interconnectivity and the limitations of forming porous electrodes, which restrict current density and increase the cost of silicon area usage.
Innovation Solution
The solution involves forming fuel cells in a single layer of conductive monocrystalline silicon with parallel trenches to create back-to-back semi-cells, filled with ion exchange resin, allowing for monopolar or bipolar configurations, and using internal ducts for reagent distribution, eliminating the need for separate dies and enhancing mechanical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate dies are joined with ion exchange resin separator to form fuel cells, then the fuel cell structure is complete with proper separation of electrodes, but the device complexity increases and mechanical sturdiness decreases
Solution Approach 1:
The patent merges the anode and cathode chambers into a single silicon die, eliminating the need for separate dies and ion exchange resin separators. The silicon substrate itself serves as the structural support and separator, integrating multiple functions into one component, thereby reducing construction complexity and improving mechanical sturdiness.
Solution Approach 2:
The silicon die performs multiple functions simultaneously: it serves as the substrate, the separator between chambers, the structural support, and the mounting platform for electrodes and ducts. This multi-functionality eliminates the need for additional components like separate separators and reduces overall device complexity.
2Productivity
If porous catalytic electrodes are formed on silicon substrate, then the fuel cell can transform chemical energy to electrical energy, but the current density is restricted and silicon area cost increases
Solution Approach 1:
The patent transitions from planar electrodes to three-dimensional vertically-oriented electrodes extending into the silicon substrate. This vertical configuration increases the effective electrode surface area without proportionally increasing the silicon footprint, thereby improving energy conversion efficiency while reducing silicon area usage.
Solution Approach 2:
The patent employs porous silicon structures as catalytic electrodes, which provide high surface area to volume ratio. The porous structure allows for increased reaction sites within a compact volume, enhancing current density and energy conversion efficiency without requiring excessive silicon area.
3Reliability
If ion exchange resin membrane is sandwiched between silicon semicells, then proper separation and ionic conduction is achieved, but mechanical stresses are introduced and construction becomes complex
Solution Approach 1:
The patent extracts and eliminates the ion exchange resin separator from the conventional sandwich structure. Instead of placing resin between separate semicells, the silicon substrate itself provides the separation function, removing the source of mechanical stress and construction complexity associated with resin sandwiching.
Solution Approach 2:
The silicon substrate serves its own separation function without requiring an additional ion exchange resin layer. The inherent properties of silicon provide both structural support and chamber separation, making the system self-sufficient and eliminating components that introduce mechanical stress.
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 approach simplifies the construction, increases current density, and reduces the cost of silicon area usage, enabling a more reliable and efficient energy delivery per unit area of silicon, while avoiding the mechanical stresses associated with sandwiching ion exchange resin membranes.
Implementation Method 1
fuel cells capable of transforming chemical oxidation energy of a fuel (typically hydrogen or methanol or other oxidable compound in gaseous form of in solution), into electrical energy
Implementation Method 2
a solid polymer electrolyte constituted by a film of ion exchange resin, typically for protons (H+)
Implementation Method 3
porous catalytic electrode (anode) from the oxygen (air or oxygen in a mixture or pure oxygen) fed to the positive porous catalytic positive counterelectrode (cathode)
Data Source
AI summary
Fuel cells are formed in a single layer of conductive monocrystalline silicon including a succession of electrically isolated conductive silicon bodies separated by narrow parallel trenches etched through the whole thickness of the silicon layer. Semicells in a back-to-back configuration are formed over etch surfaces of the separation trenches. Each semicell formed on the etch surface of one of the silicon bodies forming an elementary cell in cooperation with an opposite semicell formed on the etch surface of the next silicon body of the succession, is separated by an ion exchange membrane resin filling the separation trench between the opposite semicells forming a solid electrolyte of the elementary cell. Each semicell includes a porous conductive silicon region permeable to fluids, extending for a certain depth from the etch surface of the silicon body, at least partially coated by a non passivable metallic material. Each of the porous and fluid permeable regions communicates with a feed duct of a fuel fluid or of oxygen gas that extends parallel to the etch surface inside the conductive silicon body.