Vented Pressure Sensor Module for Minute Nozzle Pressure Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing pressure sensor modules for dispensing apparatuses are complex, prone to misalignment, and lack efficient methods for forming ventilation paths and electrical signal extraction, making them unsuitable for accurately measuring minute pressure changes near nozzles.
Innovation Solution
A pressure sensor module with a flow path substrate, semiconductor chip, and cap structure that includes a ventilation path and branch path, utilizing a multilayer mask method for trench formation and precise bonding to enable accurate pressure measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a three-layer stacked structure (cap substrate, silicon wafer, pedestal substrate) is used to improve pressure sensor functionality, then measurement capability is enhanced, but device complexity increases due to two bonding portions and multiple alignment requirements
Solution Approach 1:
The pressure sensor is divided into two independent single-layer structures: a cap substrate with cavity/ventilation path and a silicon wafer with piezoresistive element, which are bonded together. This segmentation eliminates the need for a complex three-layer stacked structure while maintaining pressure sensing functionality.
Solution Approach 2:
The cap substrate and silicon wafer are merged through direct bonding to form a functional pressure sensor. This merging combines the cavity structure for pressure application with the piezoresistive sensing element in a single integrated unit, avoiding the complexity of multiple bonding interfaces.
2Measurement precision
If two bonding portions are used in the three-layer structure to achieve pressure sensing, then measurement functionality is improved, but manufacturing precision requirements increase due to misalignment risks at multiple bonding sites
Solution Approach 1:
The sensor is segmented into two main components (cap substrate and silicon wafer) that are bonded at a single interface. This reduces the number of bonding operations from two to one, thereby reducing cumulative misalignment errors and simplifying manufacturing precision requirements.
3Measurement precision
If the silicon wafer is thinned by etching or polishing to improve sensitivity, then measurement precision increases, but device strength decreases making the structure more fragile
Solution Approach 1:
The thickness of the silicon wafer is optimized to balance sensitivity and strength. Rather than excessive thinning, a moderate thickness is selected that provides sufficient deformation for piezoresistive sensing while maintaining adequate mechanical strength to prevent fragility.
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 solution allows for a small and highly accurate pressure sensor module capable of measuring minute pressure changes near nozzles, improving dispensing apparatus accuracy and reliability.
Implementation Method 1
a piezoresistive element or the like on a diaphragm made of a silicon material... an amount of change in the diaphragm is electrically measured as a change in resistance by a Wheatstone bridge circuit
Implementation Method 2
it is possible to improve sensitivity of the strain-sensitive element when a pressure is applied by thinning, using a method of etching or polishing, a silicon wafer where the strain-sensitive element is formed
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
Provided is a small and highly accurate pressure sensor module that can be disposed in the vicinity of a nozzle of a dispensing apparatus and can measure a minute pressure change during aspiration and discharge. The pressure sensor module includes a flow path substrate including therein a flow path and a branch path branched from the flow path, a semiconductor chip including a piezoresistive element and covering an opening of the branch path, and a cap bonded onto the semiconductor chip to cover the piezoresistive element and forming a cavity between the cap and the semiconductor chip. A ventilation path that allows the cavity to communicate with outside is formed in the cap or a bonding portion between the cap and the semiconductor chip, and a shape of the opening of the branch path and a shape of the cavity are substantially similar in a normal direction.