Liquid-Drug Administration Device Occlusion Detection
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Solution Overview
Problem
Existing liquid-drug administration devices face challenges in accurately detecting occlusion, which can lead to inconsistent drug delivery and potential complications in continuous drug administration.
Innovation Solution
A liquid-drug administration device equipped with an occlusion detector featuring a fixed slit disk and a slit disk, connected by a torsion spring, uses an optical sensor to detect the overlap of slits and accurately measure back pressure, enhancing occlusion detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single slit disk encoder is used to detect occlusion, then the device structure is simple, but the occlusion detection accuracy is insufficient
Solution Approach 1:
The single slit disk encoder is segmented into two separate slit disks: a first slit disk fixed to the motor shaft and a second slit disk fixed to the lead screw. This segmentation allows independent measurement of motor rotation and lead screw rotation, enabling detection of rotational difference that indicates occlusion, thereby improving detection accuracy while maintaining reasonable structural complexity
Solution Approach 2:
A torsion spring is introduced as an intermediary element connecting the first and second slit disks. The torsion spring transmits and compares the rotational positions of both disks to the optical sensor, serving as a mechanical mediator that enables the detection system to measure back pressure and detect occlusion through rotational difference without direct mechanical coupling between the motor and lead screw
2Reliability
If a diaphragm-based pressure sensor is used for occlusion detection, then occlusion can be detected, but the device size increases and manufacturing cost rises
Solution Approach 1:
The diaphragm-based pressure sensor is replaced with a purely mechanical encoder system using slit disks and a torsion spring. This mechanical substitution eliminates the need for diaphragms, pressure-sensitive materials, and associated electronics, thereby reducing device size and simplifying manufacturing while maintaining reliable occlusion detection through rotational difference measurement
Solution Approach 2:
Instead of directly measuring pressure with a diaphragm, the system creates a mechanical copy of the pressure effect through the torsion spring, which twists in response to back pressure and translates this into measurable rotational difference between the two slit disks, providing an indirect but reliable measurement method that simplifies the overall system
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 device achieves high accuracy in occlusion detection, ensuring reliable drug delivery and reducing the risk of complications, while also allowing for downsizing and cost reduction by eliminating the need for a diaphragm-based occlusion detection system.
Implementation Method 1
an occlusion detector (20) having an encoder which detects overlapping of slits of a fixed slit disk (21) and a slit disk (23)
Implementation Method 2
a fixed slit disk (21) and a slit disk (23) via a torsion spring (25)
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
The liquid-drug administration device according to the present invention includes an actuator (11), gears (13, 15, 17) driven by the actuator (11), an output shaft (19) provided on the rotation axis of the gear (17) to slide a plunger (103) in a syringe (101) for containing liquid-drug, and an occlusion detector (20) provide between the actuator (11) and the output shaft (19) to detect occlusion in a flow passage for liquid-drug supplied from a syringe (101). The occlusion detector (20) includes a fixed slit disk (21) that has a slit (s1) in its disk face and rotates in synchronization with the rotation of the actuator (11), a slit disk (23) that has a slit (s2) in its disk face and rotates in synchronization with the rotation of the output shaft (19), the slit disk (23) being coaxially and overlappingly assembled to the fixed slit disk (21), and an elastic member (25) that connects the fixed slit disk (21) to the slit disk (23) to cause a delay in rotation of the slit disk (23) with respect to the rotation of the fixed slit disk (21) in response to the rise in the back pressure on the slit disk (23).