SAW Sensor Chip Phase-Difference Timing for Specimen Measurement
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Solution Overview
Problem
Existing specimen liquid sensors face challenges in accurately measuring specific components in a specimen liquid due to limitations in detecting phase changes of surface acoustic waves, particularly in determining the optimal timing for signal measurement.
Innovation Solution
A measurement method utilizing a sensor chip with a plurality of SAW elements on a piezoelectric substrate, where a reference SAW element and a detection SAW element have a specific relationship (t·V<L) to calculate the phase difference change over time, allowing for precise detection of the extreme value indicating the specimen liquid's flow, enabling accurate concentration measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single SAW element is used for detection, then the device structure is simple, but the measurement precision of phase change detection is insufficient
Solution Approach 1:
The sensor chip is segmented into multiple SAW elements (reference SAW element and detection SAW element) that are spatially separated and functionally distinct. The reference SAW element provides a stable phase reference while the detection SAW element measures phase changes caused by specimen liquid, enabling precise differential measurement of phase changes.
Solution Approach 2:
The reference SAW element acts as an intermediary that provides a stable phase reference signal. By comparing the phase of the detection SAW element against this reference, the system can accurately measure phase changes caused by specimen liquid binding events, eliminating the need for complex external reference systems.
2Measurement precision
If multiple SAW elements are arranged along the flow direction with specific spacing, then the measurement precision is improved, but the device complexity increases
Solution Approach 1:
The spacing between SAW elements is optimized based on the flow velocity characteristics of the specimen liquid. By setting the distance L between reference and detection SAW elements according to the relationship L < V·t (where V is flow velocity and t is measurement time), the system achieves optimal measurement precision while maintaining a manageable device structure.
3Measurement precision
If the SAW elements are positioned to detect extreme values of phase difference, then the concentration measurement accuracy is improved, but the difficulty of detecting and measuring increases
Solution Approach 1:
The system continuously monitors the phase difference between reference and detection SAW elements and identifies extreme values (maximum or minimum points) in the phase difference signal. These extreme values correspond to specific moments when specimen liquid reaches the detection zone, providing clear feedback for accurate concentration measurement timing.
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 method ensures easy and accurate measurement of detection targets in the specimen liquid by using the extreme value or later as the starting point for signal measurement, improving the precision and reliability of concentration measurements.
Implementation Method 1
a SAW sensor of which size can be reduced attracts attention... The SAW sensor has an input electrode for generating a surface acoustic wave (SAW) from an electric signal
Implementation Method 2
the SAW sensor analyzes the output signal resulting from bonding of the antigen and the antibody and find the component of the specimen liquid based on the change in the phase characteristics of the SAW
Data Source
AI summary
A measurement method of a specimen liquid includes preparing a sensor chip comprising a reference SAW element and a detection SAW element have a relationship of an expression: t·V<L, where t, V and L denote is as defined in the specification; causing the specimen liquid to flow in order from either one of the reference SAW element and the detection SAW element: calculating a change with time of a phase difference Δθ between a phase θref in the reference SAW element and a phase θtest in the detection SAW element; and measuring a detection target from a starting point which is a point in time at an extreme value or later in the change with time of the phase difference Δθ.