Microfabricated Atomic Clock Sensor Cell Recess Design
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Solution Overview
Problem
Integrated microfabricated sensors face signal degradation due to condensation of sensor fluid on windows, exacerbated by silicon's high thermal conductivity, and reducing wall thickness is challenging without propagating cracks and fractures during singulation.
Innovation Solution
The sensor cell design includes recesses on opposing exterior sides of the cell body, allowing for thinner walls that reduce thermal conduction and crack propagation, with windows attached before singulation to maintain structural integrity and enable effective thermal gradient generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the wall thickness of the cell body is reduced to enable larger thermal gradient, then the thermal gradient magnitude increases, but cracks and fractures propagate from singulation surfaces causing structural failure
Solution Approach 1:
The patent performs preliminary actions by forming recesses in the cell body walls before the singulation process. These recesses are strategically positioned to ensure that when the cell is singulated from the substrate, the cutting path does not traverse through the thinnest wall sections, thereby preventing crack propagation while maintaining the desired thin wall configuration for thermal gradient generation
2Manufacturing precision
If silicon material is used for the cell body due to its fabrication advantages, then manufacturing precision is improved, but thermal conductivity increases which reduces thermal gradient magnitude
Solution Approach 1:
The patent changes the geometric parameters of the cell body by introducing recesses that reduce the effective wall thickness in specific regions. This parameter change decreases the thermal conduction path length, thereby increasing the thermal gradient magnitude while maintaining silicon material for its fabrication advantages. The recesses create localized thermal insulation zones that compensate for silicon's high thermal conductivity
3Reliability
If thermal gradient is increased to prevent condensation on windows, then condensation is reduced improving signal transmission, but energy consumption increases
Solution Approach 1:
The patent changes the geometric parameter of wall thickness by incorporating recesses, which reduces the thermal mass and thermal conduction capacity of the cell body walls. This allows achieving the necessary thermal gradient for condensation prevention with lower heating power, thereby improving signal transmission quality while reducing energy consumption compared to thick-walled designs
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 design enhances thermal gradient generation with reduced power consumption and minimizes crack propagation, improving signal transmission by maintaining a larger thermal gradient while preventing mechanical stress-induced fractures.
Implementation Method 1
When the integrated microfabricated sensor is not in operation, the sensor fluid cools and condenses inside the cavity. Condensation of the sensor fluid on the windows degrades signal transmission during subsequent periods of operation.
Implementation Method 2
silicon has a high thermal conductivity, which reduces the magnitude of the thermal gradient, thus exacerbating the condensation problem
Data Source
AI summary
An integrated microfabricated sensor includes a sensor cell having a cell body, a first window attached to a first surface, and a second window attached to a second surface, opposite to the first window. The cell body laterally surrounds a cavity, so that the first window and the second window are exposed to the cavity. The sensor cell contains a sensor fluid material in the cavity. The cell body has recesses on opposing exterior sides of the cell body; each recess extends from the first surface to the second surface. Exterior portions of the cell body wall in the recesses are recessed from singulation surfaces on the cell body exterior. The cell body is formed by etching the cavity and the recesses concurrently through a body substrate. After the windows are attached, the sensor cell is singulated from the body substrate through the recesses.