Microfluidic Electrochemical Flow Sensing via Amperometric Time Delay
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Solution Overview
Problem
Existing microfluidic devices for measuring sweat flow rates are expensive, bulky, unreliable, and irreversible, making them unsuitable for continuous monitoring due to irreversible modifications upon sweat collection.
Innovation Solution
A microfluidic electrochemical device with a flexible design, incorporating a pair of working electrodes and a reference electrode in a microfluidic channel, uses amperometry to measure flow rate based on the time delay between amperometric signals without determining chemical species concentration, allowing for continuous, cost-effective, and reliable sweat flow rate monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If thermal flow sensors or Coriolis effect micro-flowmeters are used to measure micro-flow rates, then measurement capability is achieved, but the devices become expensive, bulky, and unreliable
Solution Approach 1:
The patent replaces mechanical flow measurement systems (thermal flow sensors, Coriolis effect micro-flowmeters) with an electrochemical measurement system. The invention uses amperometric detection with working electrodes to measure flow rates based on the time delay between electrochemical signals, eliminating the need for complex mechanical or thermal sensing components. This substitution achieves micro-flow rate measurement capability while significantly reducing device size, cost, and complexity.
2Ease of manufacture
If colorimetric techniques are used to measure sweat micro-flow rates, then ease of manufacture is improved, but the measurement becomes irreversible and the device cannot be reused
Solution Approach 1:
The patent changes the measurement parameter from chemical (colorimetric detection requiring dye reactions) to electrochemical (amperometric detection). By measuring the time delay between amperometric signals at different electrode positions, the system achieves flow rate measurement without consuming or permanently modifying the sweat sample. This allows the microfluidic channel and electrodes to be reused multiple times while maintaining ease of manufacture through simple electrochemical cell design.
3Measurement precision
If electrodes are disposed along microfluidic channels to monitor filling rate, then flow rate measurement is achieved, but the channels become permanently modified and cannot be used again
Solution Approach 1:
The patent enables continuous flow rate measurement by positioning multiple working electrodes along the microfluidic channel to detect the continuous passage of sweat. The amperometric signals from these electrodes provide ongoing flow rate data without consuming the sweat sample or permanently modifying the channel. This continuous measurement capability maintains channel reusability while achieving precise micro-flow rate monitoring over extended periods.
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 provides a space-saving, low-cost solution for continuous sweat flow rate measurement, suitable for lab-on-a-chip platforms, without requiring moving parts or assumptions about hydrodynamic regimes, and is applicable for monitoring hydration levels and diagnosing hypohidrosis.
Implementation Method 1
an electrochemical amperometry measurement system configured to bias the first working electrode at a first electrode potential and the second working electrode at a second electrode potential, so that each of said first and second working electrodes produces an amperometric signal by oxidation reaction or by reduction reaction
Implementation Method 2
each of said first and second working electrodes produces an amperometric signal by oxidation reaction or by reduction reaction of the solvent or with at least one chemical species forming a redox couple with the solvent
Implementation Method 3
each of said first and second working electrodes produces an amperometric signal by oxidation reaction or by reduction reaction of the solvent or with at least one chemical species forming a redox couple with the solvent
Implementation Method 4
each of said first and second working electrodes produces an amperometric signal by oxidation reaction or by reduction reaction of the solvent or with at least one chemical species forming a redox couple with the solvent
Data Source
AI summary
A microfluidic electrochemical device has a microfluidic channel and an electrochemical cell having a pair of working electrodes separated by an inter-electrode distance in a flow direction of the fluid in the microfluidic channel, a counter-electrode and a reference electrode. The microfluidic electrochemical device has an electrochemical amperometry measurement system configured to bias the pair of working electrodes so that each electrode produces an amperometric signal by oxidation reaction or by reduction reaction with the electroreactive fluid or with a chemical species associated with a redox couple intended for the fluid. The microfluidic electrochemical device determines the volume flow rate of the fluid in the microfluidic channel, notably based on the inter-electrode distance and a time delay between the amperometric signals produced by the pair of working electrodes.