Scanning drop sensor
Inventors
Jin, Jian • Xiang, Chengxiang • Gregoire, John
Assignees
California Institute of Technology • Lawrence Berkeley National Laboratory • University of California San Diego UCSD
Publication Number
US-9645108-B2
Publication Date
2017-05-09
Expiration Date
2033-05-31
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Abstract
Electrochemical experiments are performed on a collection of samples by suspending a drop of electrolyte solution between an electrochemical experiment probe and one of the samples that serves as a test sample. During the electrochemical experiment, the electrolyte solution is added to the drop and an output solution is removed from the drop. The probe and collection of samples can be moved relative to one another so the probe can be scanned across the samples.
Core Innovation
The invention relates to a system and method for performing electrochemical experiments by suspending a drop of electrolyte solution between an electrochemical experiment probe and a test sample. During the experiment, the system continuously adds fresh electrolyte solution to the drop and removes output solution from it, thereby refreshing the drop contents. This allows for low volume electrolyte use, typically less than 1 μL, and provides direct contact between the drop and the working and reference electrodes, resulting in low resistance in the electrochemical measurements.
The system includes features such as one or more conduits within the probe to add electrolyte solution into the drop, output conduits to remove solution from the drop, and electrodes including working, reference, and counter electrodes positioned to enable electrochemical experiments. Furthermore, the probe and the sample or samples can be moved relative to one another maintaining a constant distance to scan across multiple samples. Thus, the continuous refreshing of the drop minimizes contamination from reaction products and bubbles, and the probe need not physically contact the samples, facilitating high throughput testing.
The problem being addressed arises from existing systems for electrochemical experiments on small amounts of compounds that face high resistance between electrodes, contamination and bubble formation in the small electrolyte volumes, limited optical access for photoelectrochemical experiments, and incompatibility with scanning over multiple samples. This invention provides an improved system overcoming these issues by utilizing a suspended and refreshed electrolyte drop and relative motion between probe and samples.
Claims Coverage
The patent includes one independent claim that outlines a system for performing electrochemical experiments using a suspended electrolyte drop, supported by multiple dependent claims elaborating on specific inventive features.
System with suspended electrolyte drop between probe and test sample
An electrochemical experiment probe positioned over a test sample with a drop of liquid electrolyte solution suspended between the probe and the test sample, enabling electrochemical experimentation without direct probe contact with the sample.
Conduits integrated for controlled electrolyte addition and output removal
One or more first conduits arranged to add electrolyte solution to the suspended drop and one or more output conduits positioned adjacent to the exit of a drop conduit to remove output solution from the drop, allowing continuous refreshment of the drop contents.
Electronics controlled flow rates maintaining drop volume and flow balance
Electronics configured to control flow of electrolyte solution into the drop and flow of output solution from the drop, including controlling volumetric flow rates such that the output flow exceeds the input flow, enabling atmospheric intake to maintain drop volume.
Electrodes positioned to perform electrochemical measurements concurrently with fluid flow
Incorporation of a reference electrode with functional end in contact with the drop, a counter electrode positioned in one or more of the first conduits contacting the drop solution, and using the contact area of the drop on the test sample as the working electrode, allowing electrochemical experiments such as cyclic voltammetry to be performed concurrently with fluid flow.
Relative motion capability for scanning multiple samples without losing drop suspension
One or more actuators configured to move the sample collection and the probe relative to one another while maintaining a substantially constant distance between them, such that the drop remains suspended and positioned on different samples for high throughput scanning.
Integration of optical waveguide for photoelectrochemical experiments
An optical waveguide positioned in or near the drop conduit such that light exiting from the waveguide passes through the drop to the test sample, facilitating photoelectrochemical measurements.
The claims collectively cover a system employing a suspended, continuously refreshed electrolyte drop between probe and sample with controlled fluid flow, integrated electrodes, capability to scan multiple test samples without losing drop contact, and optional optical access, enabling versatile and efficient electrochemical and photoelectrochemical experimentation.
Stated Advantages
Provides low resistance between working and reference electrodes through direct contact with a sub-microliter electrolyte drop.
Continuous replacement of electrolyte solution minimizes contamination by reaction products and dissolution of samples.
Removal of bubbles formed during electrochemical reactions maintains good electrolyte connectivity and measurement accuracy.
Enables optical access through the electrolyte drop for photoelectrochemical experiments.
Facilitates scanning across multiple samples by relative movement without contact, maintaining the drop between probe and sample.
Reduces opportunity for cross contamination between different samples due to rapid drop refresh rates.
Documented Applications
Performing electrochemical experiments on large arrays of samples generated from combinatorial chemistry to identify catalysts or photoabsorbers.
Conducting photoelectrochemical experiments such as light-modulated cyclic voltammetry, illuminated open-circuit voltage measurements, short-circuit photocurrent measurements, and light-biased impedance measurements.
Evaluating (photo)catalysts for oxygen evolution reactions using techniques including cyclic voltammetry, chronoamperometry, and chronopotentiometry with or without chopped illumination.
High throughput scanning and testing of electrochemical properties by moving the probe or sample collection and performing experiments on multiple samples rapidly.
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