Solid Reservoir Reference Electrode
Bibliographic record
Abstract
Potentiometric sensing requires a stable sensing electrode that is selectively responsive to an analyte, and a reference electrode (RE) that provides a stable and well-defined reference potential in a liquid electrolytic environment. In sensor applications where compactness and ease of integration are essential characteristics, pseudo-REs in the form of doped polymer semiconductors, bare metal films, or a bare chlorinated silver film are typically used. Bulk glass electrodes, such as the Ag/AgCl electrode, are incompatible with sensor integration. We report here a solid reservoir reference electrode (SRRE) that achieves the performance of traditional immersed wire Ag/AgCl REs in a compact, layered structure. The SRRE is a solid, layered analogue of the Ag/AgCl RE, with a chlorinated silver film as metallic electrode, a solid KCl layer serving as a saturated reservoir of chloride, and a porous polydimethylsiloxane (PDMS) layer acting as membrane for exchange of water and ions. We demonstrate two different method to fabricate the porous PDMS in figure A and B. The characteristics of the SRRE, including impedance, noise, and long-term drift, can be tuned by adjustment of the PDMS membrane permeance and KCl solid reservoir size. We have demonstrated temporal stability of the RE open circuit potential (OCP), with drift less than 0.37 mV over 17 hours in deionized water. When compared against bare chlorinated silver, the SRRE exhibits superior stability of OCP versus changes in electrolyte ion-concentration, including solutions of potassium chloride, sodium chloride and pH buffers. The ease of fabrication enables SRRE integration with graphene ion-sensitive field effect transistors (ISFETs) to achieve entirely solid-contact micro ion sensors. The solid-contact micro ion sensor can simultaneously measure pH and Na+, in volumes as low as 20 μL. Using the same layered structure, we further demonstrated fabricated electrocardiogram (ECG) and electroencephalogram (EEG) electrodes with significantly lower impedance and noise when compared to disposable gel electrodes. Finally, we have shown that the SRRE can function in non-aqueous solventssuch as acetonitrile, demonstrating the wide range of SRRE applications. Figure 1
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.003 |
| Meta-epidemiology (narrow) | 0.003 | 0.001 |
| Meta-epidemiology (broad) | 0.003 | 0.001 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.002 | 0.002 |
| Open science | 0.007 | 0.002 |
| Research integrity | 0.004 | 0.003 |
| Insufficient payload (model declined to judge) | 0.038 | 0.030 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".