Quartz Crystal Sensor Frequency Stabilization
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Solution Overview
Problem
Existing quartz-crystal sensors for detecting trace substances in sample solutions face challenges in achieving high processing power and accuracy due to instability in oscillation frequencies and inefficient sample solution handling.
Innovation Solution
A sensing device with a piezoelectric resonator that includes a reference liquid supply system, sample solution storage, channel switching mechanisms, and a control unit to stabilize oscillation frequencies, allowing for precise measurement by switching between reference and sample solution supply modes, and automatic calculation of frequency differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a quartz-crystal sensor of flow-through cell type is used, then the frequency characteristic can be easily stabilized and liquid can be smoothly replaced, but the processing power and measurement accuracy are insufficient
Solution Approach 1:
The liquid supply path is segmented into reference liquid supply path and sample solution supply path, allowing independent optimization of each path. The reference liquid path is used for frequency stabilization while the sample solution path enables rapid measurement processing.
Solution Approach 2:
The reference liquid is supplied in advance to stabilize the oscillation frequency of the quartz-crystal resonator before sample solution measurement. This preliminary stabilization action ensures that subsequent measurements start from a stable baseline, improving both accuracy and processing efficiency.
2Ease of operation
If a quartz-crystal sensor of flow-through cell type is used, then liquid can be smoothly replaced, but measurement accuracy is insufficient
Solution Approach 1:
The reference liquid acts as an intermediary between the liquid replacement system and the measurement system. It mediates the transition by stabilizing the frequency characteristics before the actual sample solution measurement, thereby improving measurement accuracy while maintaining ease of liquid replacement.
Solution Approach 2:
The system changes the liquid parameter (from reference liquid to sample solution) in a controlled manner. By first establishing stable frequency characteristics with reference liquid and then transitioning to sample solution, the system maintains measurement precision during liquid replacement operations.
3Measurement precision
If reference liquid is supplied to stabilize oscillation frequency, then measurement accuracy improves, but processing time increases
Solution Approach 1:
The reference liquid supply operates continuously or in a continuous cycle to maintain stable frequency characteristics throughout the measurement process. This continuous stabilization eliminates the need for repeated frequency adjustments, thereby improving accuracy without significantly increasing processing time.
Solution Approach 2:
The system employs periodic reference liquid supply cycles that are optimized to provide sufficient frequency stabilization while minimizing the time spent in stabilization mode. The periodic action balances the need for frequency stability with the requirement for rapid measurement processing.
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
Ensures high-accuracy measurements by stabilizing oscillation frequencies and reducing unnecessary processing time, enabling efficient sample solution handling and precise detection of substances.
Implementation Method 1
an oscillation frequency (resonance frequency) of the quartz-crystal resonator changes when it adsorbs a trace amount of a substance
Implementation Method 2
the adsorption layer reacts with the substance to be sensed contained in the sample solution to adsorb the substance to be sensed, resulting in a mass change in the adsorption layer
Data Source
AI summary
To provide a sensing device having a high processing power and capable of high-accuracy measurement. It is determined whether or not an oscillation frequency is stabilized while a buffer solution is supplied to a quartz-crystal resonator 4. from a syringe pump 10. When it is determined that the frequency is stabilized, a second valve 14. is switched to a sample solution supply mode to supply a sample solution in an injection loop 14a. to the quartz-crystal resonator 4. An instant at which the sample solution reaches the quartz-crystal resonator 4. and an instant at which the sample solution finishes passing through the quartz-crystal resonator 4. are automatically found based on a supply flow rate of the buffer solution, a volume of the injection loop 14a, a volume of a supply channel supplying the sample solution to the quartz-crystal resonator 4, and an instant at which the second valve 14. is switched to the sample solution supply mode. An oscillation frequency before the sample solution reaches the quartz-crystal resonator 4. and an oscillation frequency after the sample solution passes through the quartz-crystal resonator 4. are found, and a difference between the oscillation frequencies is obtained.