Pipetting Flow Rate Derivative Error Detection
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Solution Overview
Problem
Existing pipetting control methods are laborious to calibrate and provide only qualitative information, failing to accurately detect errors in liquid volume measurement and flow rates during pipetting operations, which can disrupt analysis procedures.
Innovation Solution
A method that measures the flow rate of liquid suctioned or dispensed using a pipetting device, calculates the first derivative of the flow rate curve, identifies maximum and minimum values, and compares them to predetermined references to provide validation or error messages, allowing for real-time error detection independent of volumes and flow rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If reference curve calibration is used to detect pipetting errors, then error detection capability is improved, but system complexity and calibration labor increase
Solution Approach 1:
The patent extracts the essential error detection capability from complex reference curve calibration by focusing only on the critical parameter: flow rate. Instead of calibrating for multiple variables (volume, speed, liquid type, tip geometry), the invention isolates flow rate measurement as the single critical parameter for error detection, thereby simplifying the system while maintaining reliability.
Solution Approach 2:
The flow rate measurement system serves multiple functions: it detects errors during suction, verifies proper liquid contact, monitors dispensing accuracy, and identifies air bubbles. This single measurement approach replaces multiple specialized calibration systems, reducing overall system complexity while maintaining comprehensive error detection capability.
2Ease of operation
If atmospheric pressure measurement is used to monitor pipetting operations, then operational monitoring is improved, but measurement precision of liquid flow rate deteriorates
Solution Approach 1:
The patent replaces indirect mechanical pressure measurement with direct flow rate measurement. Instead of using atmospheric pressure sensors to infer pipetting status, the invention employs flow rate measurement systems that directly quantify liquid movement, providing precise measurement data without relying on indirect pressure correlations.
Solution Approach 2:
The invention introduces flow rate as an intermediary parameter that directly links the vacuum/pressure system to liquid movement. By measuring flow rate rather than pressure alone, the system gains a direct quantitative measure of liquid transfer accuracy, enabling precise detection of suction and dispensing errors.
Data Source
AI summary
A method for controlling pipetting operations done by a pipetting device having a system for measuring the flow rate of the liquid suctioned or dispensed and electronics to communicate with a computer. The method is based on detection of flow rate variations and the moments at which those variations occur. The method includes obtaining a curve of liquid flow rate by the pipette as a function of time, computing the first deviation of the curve, identifying and recording the maximum and minimum values of the first deviation and the moments at which the maximum and minimum values occur, comparing the maximum and minimum values and the moments at which the maximum and minimum values occur with predetermined references for the values and the moments at which they occur, and based on the result of the comparison, providing a validation or error message.