Digital Syringe Plunger Position Measurement
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Solution Overview
Problem
Conventional syringes used in medical settings face challenges with precision due to difficulties in reading gradations and mechanical tolerances, leading to errors in medicament delivery, especially with polymer disposable syringes which are prone to flexibility and dimensional variations.
Innovation Solution
A digital syringe system that includes a sensor system for direct measurement of plunger position, allowing for precise control of medicament delivery through electronic signals and a motor unit for automatic operation, while also enabling manual operation with a display for easy volume measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional polymer disposable syringes are used, then ease of operation and sterility are improved, but manufacturing precision and measurement precision deteriorate due to flexibility and dimensional variations
Solution Approach 1:
The patent replaces indirect mechanical measurement methods (reading gradations on the syringe) with direct electronic sensing. A sensor system electronically measures the actual position of the plunger, eliminating the need to rely on printed gradations that are difficult to read and interpret. This substitution of mechanical reading methods with electronic measurement resolves the contradiction by providing precise measurement independent of the polymer syringe's dimensional variations.
Solution Approach 2:
The patent implements a feedback mechanism where a sensor continuously monitors plunger position and provides electronic signals indicating actual movement. This feedback loop allows the system to track and record the true position of the plunger despite flexibility or dimensional variations in the polymer syringe, thereby maintaining measurement precision while using disposable syringes.
2Measurement precision
If digital syringes with precision metal components are used, then measurement precision is improved, but ease of manufacture and cost-effectiveness deteriorate
Solution Approach 1:
The patent divides the syringe system into two separate segments: a disposable polymer syringe (barrel and plunger) and a reusable sensor system. The sensor system, which provides the measurement precision, is separated from the disposable syringe components. This segmentation allows the precision measurement functionality to be reused across multiple syringes, eliminating the need to manufacture expensive precision metal components in every disposable syringe while maintaining high measurement precision.
Solution Approach 2:
The sensor system is designed as a universal device that can be reused with multiple disposable syringes. Instead of incorporating measurement components into each individual syringe, the reusable sensor system provides multi-functionality by serving as the measurement device for numerous syringes, thereby improving ease of manufacture for the disposable components while maintaining measurement precision.
3Device complexity
If indirect measurement of motor position is used, then device complexity is reduced, but measurement precision deteriorates due to mechanical tolerances and stack up
Solution Approach 1:
The patent replaces indirect mechanical measurement of motor position with direct electronic sensing of plunger position. Instead of measuring motor position and inferring plunger position (which introduces errors from mechanical tolerances, gear train inaccuracies, and lead screw variations), the sensor system directly measures the actual plunger position electronically. This substitution eliminates the chain of mechanical transformations and their associated tolerances, providing superior measurement precision.
Solution Approach 2:
The patent introduces an electronic sensor as an intermediary between the plunger and the measurement system. This sensor directly detects plunger position without requiring mechanical linkages or transformations. The electronic intermediary provides a direct measurement path that bypasses the mechanical tolerance stack-up problem inherent in indirect mechanical measurement systems.
Data Source
AI summary
A digital syringe is used with conventional polymer disposable syringe construction to be practical in the medical environment. Errors associated with the larger volumes of the syringes (which exacerbate minor errors in plunger position) and the flexibility and dimensional variations of the polymer plungers are accommodated by direct measurement of the syringe plunger position rather than indirect measurement of motor position and inference of syringe plunger position. This direct measurement eliminates mechanical tolerances (“stack up”) in the motor, gear train, and lead screw on plunger movement, an effect exacerbated by flexibility of the plunger and changes in syringe resistance and medicament viscosity, for example, with different medicaments or when the syringe is refrigerated. The digital syringe may be combined with the motor unit to provide additional versatility.