Peristaltic Pump Dosing Precision for Small Volumes
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Solution Overview
Problem
Peristaltic pumps, although inexpensive and easy to clean, are not suitable for dosing small predetermined volumes like 1000 µl or less due to high volume deviations, making them unsuitable for forming pharmaceutical units in the pharmaceutical industry.
Innovation Solution
Improvements to peristaltic pumps, including positioning the spout adjacent to the mould, displacing the roller over a predetermined length, and using segmented tubing with a smaller spout diameter, allow for precise dosing with relative standard deviations of 5% or less, enabling the use of peristaltic pumps for forming units with volumes of 1000 µl or less.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a peristaltic pump is used for dosing small volumes (1000 µl or less), then the pump is easy to clean and inexpensive to maintain, but the dosing precision deteriorates with high volume deviations (20% RSD or more)
Solution Approach 1:
The patent changes the geometric parameters of the pump system, specifically the ratio between roller diameter and tube diameter (increasing it to 0.5-2.0), and adjusts the compression force parameters. These parameter changes enable the peristaltic pump to achieve acceptable dosing precision (≤20% RSD) for small volumes while maintaining the ease of cleaning advantage, as the optimized parameters reduce fluid retention in dead space without requiring structural changes that would complicate cleaning.
2Device complexity
If a peristaltic pump is used for dosing small volumes (1000 µl or less), then the pump structure is simple and inexpensive, but the dosing accuracy deteriorates due to high relative standard deviation
Solution Approach 1:
The patent applies parameter changes by optimizing the roller-to-tube diameter ratio to 0.5-2.0 and adjusting compression force parameters. These changes improve dosing accuracy (reducing RSD to ≤20%) while maintaining the simple pump structure characteristic of peristaltic pumps, avoiding the need for complex additional components or mechanisms.
3Manufacturing precision
If plunger pumps are used for dosing small volumes (1000 µl or less), then dosing precision is high (below 5% RSD), but the pump requires frequent disassembly for cleaning, consuming significant time
Solution Approach 1:
The patent extracts the tube from the pump housing, making it a separate, removable component. This allows the tube to be easily replaced without disassembling the pump body, combining the dosing precision of plunger pumps with the ease of cleaning of peristaltic pumps. The tube can be quickly removed and replaced, eliminating time-consuming disassembly while maintaining accurate dosing through proper tube selection and installation.
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
These modifications enable peristaltic pumps to achieve accurate dosing with low relative standard deviations, making them viable for pharmaceutical applications by ensuring precise control over the dosed volume, even for small volumes like 1000 µl or less.
Implementation Method 1
A rotor with a number of 'rollers' (which term includes 'shoes' or 'wipers' and other occluding members) attached to the external circumference compresses the flexible tube. As the rotor turns, the part of tube under compression closes (or 'occludes') thus forcing the fluid to be pumped to move through the tube. Additionally, as the tube opens to its natural state after the passing of the cam ('restitution' or 'resilience') fluid flow is induced to the pump. This process is called peristalsis.
Data Source
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AI summary
The present invention pertains to a method for dosing a fluid formulation containing a medicinal substance into a mould to form a pharmaceutical unit with a volume of 1000µ? or less, using a peristaltic pump comprising a flexible tube for guiding the fluid formulation to the mould and at least one roller to compress the tube to induce a flow of the fluid formulation through the tube, the method comprising placing a spout of the tube adjacent the mould, displacing the roller over a predetermined length of the tube to dose the fluid formulation in the mould, positioning the spout such that when the dosing is finished, at least the open end of the spout is present in the dosed unit, and after dosing, retracting the spout end out of the dosed unit.