Integrated Circuit Fluid Sensor Package With Field-Based Isolation
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Solution Overview
Problem
Existing fluid sensors, such as ISFETs, face challenges with unpredictable electrical behavior due to varying threshold voltages caused by fixed and process-induced charges, and are prone to corrosion when exposed to fluids, limiting their lifespan.
Innovation Solution
An integrated circuit package is developed with a sensor circuit and a fluid property measurement circuit coupled within the same package, where the sensor circuit generates a field that interacts with the fluid without direct contact, allowing the measurement circuit to determine fluid properties without exposing the IC to corrosive effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the IC is directly exposed to the fluid for sensing, then the sensing capability is achieved, but the IC suffers corrosive effects from fluid exposure, limiting its lifetime
Solution Approach 1:
The system is divided into two separate circuits: a sensor circuit that generates the field and interacts with the fluid, and a measurement circuit that remains protected from fluid exposure. The sensor circuit is positioned to allow field interaction while the measurement circuit is isolated, enabling the sensing function to be performed without exposing the entire IC to corrosive fluid effects.
Solution Approach 2:
A field (electric or magnetic) serves as an intermediary between the sensor circuit and the fluid. The sensor circuit generates this field that penetrates or interacts with the fluid, allowing the measurement circuit to detect fluid properties indirectly through field interactions rather than direct fluid contact, thereby protecting the IC from corrosion.
2Measurement precision
If the threshold voltage of ISFET is used for sensing, then the ion concentration can be measured, but the threshold voltage varies widely due to fixed charge and process-induced charges, making electrical behavior unpredictable
Solution Approach 1:
Instead of relying on a single ISFET with unpredictable threshold voltage, the system uses multiple sensor elements that generate fields with similar characteristics. By measuring the response of multiple identical or matched sensor circuits and comparing their outputs, the system can eliminate variations due to manufacturing tolerances and fixed charges, achieving more predictable and reliable measurements.
Solution Approach 2:
The system measures the field generated by the sensor circuit and uses this information to adjust or compensate for threshold voltage variations. By continuously monitoring the electrical behavior and comparing it against expected values, the system can identify and correct for variations caused by fixed charges and process-induced charges, maintaining measurement accuracy.
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 solution enables accurate and reliable fluid property sensing while protecting the IC from corrosion, enhancing the operational life and sensitivity of the sensor system.
Implementation Method 1
the sensor circuit is configured to generate an electric or magnetic field that penetrates or contacts the fluid
Implementation Method 2
the sensor circuit is configured to generate an electric or magnetic field that penetrates or contacts the fluid
Data Source
AI summary
An integrated circuit package for sensing fluid properties includes: a substrate made of semiconductor material; a fluid property measurement circuit formed on the substrate; and a sensor circuit coupled to the fluid property measurement circuit within a same integrated circuit package. The sensor circuit is configured to generate a field that interacts with the fluid. The fluid property measurement circuit is configured to determine a change in a property of the sensor circuit as results from the field interacting with the fluid and is further configured to determine a property of the fluid based on the change in the property of the sensor circuit.