SAW Sensor Signal Blending for High Resolution Substance Detection
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Solution Overview
Problem
Conventional SAW sensors face limitations in achieving high resolution and wide frequency bandwidth for effective substance detection, particularly due to the need for narrow electrode gaps and frequency separation challenges when using multiple sensors or network analyzers.
Innovation Solution
A SAW sensor system utilizing a pseudo random sequence to generate signals with a wide frequency bandwidth, blending these signals with a center frequency signal to produce a blended signal that is applied to a wave generator, allowing for improved detection of substances by analyzing changes in the output signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a network analyzer is used to generate signals for multiple SAW sensors, then frequency separation of several kHz or greater is achieved, but resolution and detection precision deteriorate
Solution Approach 1:
The patent segments the frequency bandwidth into multiple narrowband components, each centered at the SAW resonant frequency. By using a pseudo-random sequence signal with bandwidth much narrower than the separation between multiple SAW sensors, the system can resolve individual sensor responses without requiring large frequency separation, thus improving resolution while maintaining adaptability.
Solution Approach 2:
The patent changes the signal parameter from conventional single-frequency or wide-frequency signals to pseudo-random sequence signals with specific autocorrelation properties. This parameter change allows the system to achieve high resolution through signal processing of the broadened output signal, rather than relying on large frequency separation between sensors.
2Power
If narrow gap between input and output electrodes is used, then SAW generation efficiency is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent employs feedback signal processing where the broadened output signal from the SAW sensor is correlated with the original pseudo-random sequence. This feedback mechanism allows for precise measurement of SAW properties even with variations in electrode gap, compensating for manufacturing tolerances and maintaining high measurement precision without requiring extremely narrow and precise electrode gaps.
3Productivity
If wide frequency bandwidth signal is applied to SAW element, then detection capability is improved, but signal processing complexity increases
Solution Approach 1:
The patent uses the pseudo-random sequence as a reference copy that is correlated with the broadened output signal from the SAW sensor. This copying approach simplifies the signal processing by using correlation techniques rather than complex spectral analysis, making the system capable of handling wide bandwidth signals while keeping processing complexity manageable through the use of the reference signal copy.
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 proposed solution enhances the resolution and detection capabilities of SAW sensors by enabling the generation of signals with a wide frequency bandwidth, allowing for more precise sensing of substances through changes in signal properties such as center frequency, phase, and amplitude.
Implementation Method 1
In a SAW sensor using a piezoelectric material, a SAW may be created when a radio frequency ("RF") signal is applied to an input electrode
Implementation Method 2
The SAW may be converted again into an electrical signal and outputted from an output electrode
Data Source
AI summary
A surface acoustic wave (“SAW”) sensor includes; a first signal generator which generates a first signal having a predetermined frequency bandwidth using a pseudo random sequence, a second signal generator which generates a second signal with a predetermined frequency, a signal blender which blends the first signal with the second signal to generate a blended signal having the predetermined frequency bandwidth with the predetermined frequency as a center frequency, a wave generator which generates a surface acoustic wave using the blended signal, which converts the surface acoustic wave into a third signal after the surface acoustic wave travels a predetermined distance, and which outputs the third signal, and a signal detector which detects a change in the third signal from the wave generator to sense a substance bound to the wave generator.