Monolithic Microfluidic Electrochemical Sensor with In-Line Calibration
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Solution Overview
Problem
Electrochemical sensors face challenges with long-term performance due to electrode fouling and degradation in harsh environments, particularly in in-vivo applications, where rapid degradation leads to short sensor lifetimes and requires time-consuming and invasive maintenance.
Innovation Solution
Integration of electrodes within microfluidic channels protected from the surrounding environment, with a reagent channel for in-line cleaning, calibration, and regeneration, using a unitary silicon substrate to minimize tissue disruption and extend operational lifetime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electrodes are exposed to the surrounding environment for analyte detection, then detection sensitivity is improved, but electrode fouling and degradation occur rapidly
Solution Approach 1:
The device is divided into distinct functional zones: a sampling port region for analyte intake, a microfluidic channel for transport, and a sensing region with electrodes protected within the channel. This segmentation allows the electrodes to remain isolated from direct environmental exposure while still performing detection functions through the controlled microfluidic environment.
Solution Approach 2:
A microfluidic channel acts as an intermediary between the external environment and the electrodes. The channel delivers analytes to the electrodes in a controlled manner, enabling detection while protecting the electrodes from direct contact with fouling agents in the surrounding environment.
2Duration of action of stationary object
If sensor lifetime is extended by protecting electrodes, then operational duration is improved, but active manipulation and maintenance are required
Solution Approach 1:
The microfluidic channel system enables self-cleaning and self-regeneration of electrodes through automated fluid flow. Reagents and cleaning solutions can be delivered through the same channel system without requiring manual intervention, allowing the sensor to maintain itself autonomously during operation.
Solution Approach 2:
The microfluidic channel serves multiple functions: analyte delivery, electrode protection, and self-cleaning/ regeneration. This multi-functionality eliminates the need for separate maintenance mechanisms and allows a single system to handle both detection and self-maintenance tasks.
3Object-affected harmful factors
If sensor size is reduced for minimal tissue disruption, then tissue damage is minimized, but sample collection capability is limited
Solution Approach 1:
A pump system integrated into the device creates controlled fluid flow through the microfluidic channels, enabling efficient sample collection and transport despite the small sensor size. The hydraulic system overcomes the limitations of miniaturization by using pressure-driven flow to ensure adequate sample delivery to the electrodes.
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 solution enables long-term, high-resolution, and sensitive analyte detection with minimal tissue damage, achieving operational lifetimes greater than one hour without active sensor manipulation, and allows for precise control over sample collection and analysis.
Implementation Method 1
A microelectrode forms a portion of the lumen surface and is configured for fluid contact with a fluid sample that flows in the microfluidic lumen to detect the analyte
Implementation Method 2
A reagent channel is fluidically connected to the microfluidic channel, wherein the reagent channel is configured to introduce a reagent solution to the microelectrode for microelectrode calibration and/or cleaning
Data Source
AI summary
Provided are electrochemical sensors for analyzing analytes. The sensors may comprise an implantable probe for analyzing a biological analyte, with those sensors described as electrochemical biosensors. Also provided are related methods of using and making the sensors. The electrochemical sensor is formed with an integrated on-chip probe body that provides for a buried microelectrode in a microfluidic channel etched in the probe body, such as a doped Si substrate. The fluidic system can, therefore, be quite small and suitable for in-vivo implantation and use, while withstanding high pressure. The fluidic system has specially-configured reagent channel to provide for periodic and convenient calibration, electrode cleaning and/or regeneration, without having to remove any sensor component from the implantation site.