Injection Device Stopping Member for Microinjection Precision
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Solution Overview
Problem
Ordinary syringes in the prior art cannot meet the requirements of microinjection due to excessive errors in dose measurement, especially for microinjections of 50, 100, or 200 microliters, where the error needs to be within ±10% or ±5 microliters.
Innovation Solution
An injection device is provided that does not change the original structure of a syringe, featuring a barrel with a flange and a push rod connected with a stopping member. The stopping member has a first stopping portion and a second stopping portion at different positions, allowing for precise control of the injection dose by determining the fixed distance between these portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional syringes with graduation marks are used for microinjection, then the device structure remains simple and cost-effective, but the measurement precision of injection dose cannot meet the requirements (error exceeds ±10%)
Solution Approach 1:
A stopping member is introduced as an intermediary component between the push rod and the user's finger. This stopping member features a first stopping surface and a second stopping surface at a fixed distance apart, which limits the push rod's travel distance. By using this mechanical intermediary, the syringe achieves precise microinjection (within ±10% error) without requiring complex electronic control systems, thereby resolving the contradiction between measurement precision and device complexity.
2Adaptability or versatility
If multiple tolerance parameters (D, L1, L2, L3, L4) are involved in calculating injection dose, then the syringe can accommodate various dimensions, but the accumulation of tolerances increases the dose error to about 18%
Solution Approach 1:
The invention extracts and isolates the critical dimension parameter by fixing the distance between the first and second stopping surfaces of the stopping member. Instead of relying on multiple dimensional parameters (D, L1, L2, L3, L4) that accumulate tolerances, the dose is determined primarily by the single fixed distance parameter between stopping surfaces. This extraction of the key dimension reduces tolerance accumulation from five parameters to essentially one critical parameter, thereby improving dose precision while maintaining adaptability.
3Measurement precision
If special microsyringes are used to achieve accurate microinjection, then the injection precision meets requirements, but the cost increases and ordinary syringes are not available
Solution Approach 1:
The stopping member is designed as a universal component that can be attached to ordinary syringes to transform them into precise microinjection devices. Rather than requiring specially manufactured microsyringes, the stopping member provides the precision function across different syringe types. This multi-functional approach allows ordinary syringes to achieve microinjection precision (within ±10% or ±5 microliters), thereby reducing manufacturing costs while maintaining high precision.
4Productivity
If the push rod is pushed until the rubber stop contacts the bottom of the injection barrel, then the injection is completed, but the rubber stop deforms and squeezes out medication, increasing dose error to about 20% or more
Solution Approach 1:
The stopping surfaces on the stopping member perform a preliminary action by limiting the push rod's travel distance before the rubber stop reaches the bottom of the barrel. The first stopping surface prevents over-pushing, and the second stopping surface provides a reference point. This preliminary limitation of travel distance prevents rubber stop deformation and medication squeeze-out, maintaining dose precision within ±10% while ensuring complete injection through the controlled movement.
Data Source
AI summary
Provided are an injection device, an injection device without changing an original structure of a syringe, and a method for using the same. The injection device includes a barrel (1) with a flange (8) and a push rod (2) slidably connected in the barrel (1). One end of the push rod (2) is provided with a piston (3), and the other end is provided with a thumb rest (4). The push rod (2) or the barrel (1) is detachably connected with a stopping member (5), and the stopping member (5) is provided with a first stopping portion (51) and a second stopping portion (52) at different positions. A distance between the first stopping portion (51) and the second stopping portion (52) is a fixed distance. The push rod (2) is moved, and when the thumb rest (4) or the flange (8) abuts against the first stopping portion (51), the injection device is in an injection start position; and when the thumb rest (4) or the flange (8) abuts against the second stopping portion (52), the injection ends, and a gap is left between the piston (3) and the barrel (1). As long as the fixed distance between the first stopping portion and the second stopping portion is determined, the number of tolerances can be greatly reduced, thereby improving the injection accuracy. The piston (3) and a bottom of the barrel (1) do not squeeze each other, so that the piston will not deform. Therefore, a residual medication in a tapper cavity will not be squeezed out for injection, thereby improving the injection accuracy.