Voltammetric pH sensor based on electrochemically modified pseudo-graphite

The Analyst ◽  
2020 ◽  
Vol 145 (22) ◽  
pp. 7252-7259 ◽  
Author(s):  
Haoyu Zhu ◽  
Tanim Hassan ◽  
Humayun Kabir ◽  
Jeremy May ◽  
Kailash Hamal ◽  
...  
Keyword(s):  
Amorphous Carbon ◽  
Ph Sensor ◽  
Ph Sensing ◽  
Sensing Range ◽  
Nanocrystalline Graphite ◽  
The University ◽  
University Of Idaho

A nanocrystalline graphite-like amorphous carbon (graphite from the University of Idaho thermolyzed asphalt reaction, GUITAR) is electrochemically modified for voltammetric pH sensing. This electrode has a pH sensing range from 0 to 11.

scholarly journals Titanium Nitride Thin Film Based Low-Redox-Interference Potentiometric pH Sensing Electrodes

Sensors ◽  
2020 ◽  
Vol 21 (1) ◽  
pp. 42
Author(s):  
Shimrith Paul Shylendra ◽  
Wade Lonsdale ◽  
Magdalena Wajrak ◽  
Mohammad Nur-E-Alam ◽  
Kamal Alameh
Keyword(s):  
Thin Film ◽  
Titanium Nitride ◽  
Orange Juice ◽  
Ph Sensor ◽  
Reference Electrode ◽  
Cost Effective ◽  
Ph Sensing ◽  
Ph Sensors ◽  
Potential Shift ◽  
Double Junction

In this work, a solid-state potentiometric pH sensor is designed by incorporating a thin film of Radio Frequency Magnetron Sputtered (RFMS) Titanium Nitride (TiN) working electrode and a commercial Ag|AgCl|KCl double junction reference electrode. The sensor shows a linear pH slope of −59.1 mV/pH, R2 = 0.9997, a hysteresis as low as 1.2 mV, and drift below 3.9 mV/h. In addition, the redox interference performance of TiN electrodes is compared with that of Iridium Oxide (IrO2) counterparts. Experimental results show −32 mV potential shift (E0 value) in 1 mM ascorbic acid (reducing agent) for TiN electrodes, and this is significantly lower than the −114 mV potential shift of IrO2 electrodes with sub-Nernstian sensitivity. These results are most encouraging and pave the way towards the development of miniaturized, cost-effective, and robust pH sensors for difficult matrices, such as wine and fresh orange juice.

scholarly journals Ruthenium Oxide pH Sensing for Organs-On-Chip Studies

Proceedings ◽  
2018 ◽  
Vol 2 (13) ◽  
pp. 709 ◽  
Author(s):  
Esther Tanumihardja ◽  
Wouter Olthuis ◽  
Albert van den Berg
Keyword(s):  
Ph Sensor ◽  
Ruthenium Oxide ◽  
Open Circuit ◽  
Biological Medium ◽  
Similar Response ◽  
Ph Sensing ◽  
Ph Sensors ◽  
Cross Sensitivity ◽  
On Chip

A ruthenium oxide (RuOx) electrode is being developed as potentiometric pH sensor for organs-on-chip applications. Open-circuit potential (OCP) of the RuOx electrode showed a response of −58.05 mV/pH, with no cross-sensitivity to potentially interfering/complexing ions (tested were lithium, sulfate, chloride, and calcium ions). Similar response was observed in complex biological medium. The electrode stored in liquid had a long-term drift of −0.8 mV/hour (corresponding to ΔpH of 0.013/hour) and response time in complex biological medium was 3.7 s. Minimum cross-sensitivity to oxygen was observed as the OCP shifted ~3 mV going from deoxygenated to oxygenated solution. This response is one magnitude lower than previously reported for metal- oxide pH sensors. Overall, the RuOx pH sensor has proven to be a suitable pH sensor for organs- on-chip applications.

scholarly journals Adapting The Mit Stirling Engine Project At The University Of Idaho, A Land Grant Institution

2020 ◽  
Author(s):  
Nathaniel Allen ◽  
Mike Klein ◽  
Matthew Cunnington ◽  
Levi Westra ◽  
Ronald Smelser ◽  
...  
Keyword(s):  
Stirling Engine ◽  
Land Grant ◽  
Land Grant Institution ◽  
The University ◽  
University Of Idaho

scholarly journals Tryptophan 207 is crucial to the unique properties of the human voltage-gated proton channel, hHV1

2015 ◽  
Vol 146 (5) ◽  
pp. 343-356 ◽  
Author(s):  
Vladimir V. Cherny ◽  
Deri Morgan ◽  
Boris Musset ◽  
Gustavo Chaves ◽  
Susan M.E. Smith ◽  
...  
Keyword(s):  
Transmembrane Helix ◽  
Ph Sensor ◽  
Proton Channel ◽  
Tryptophan Residue ◽  
Ph Sensing ◽  
Ph Sensors ◽  
Voltage Gated ◽  
Karlodinium Veneficum ◽  
Channel Opening ◽  
External Ph

Part of the “signature sequence” that defines the voltage-gated proton channel (HV1) is a tryptophan residue adjacent to the second Arg in the S4 transmembrane helix: RxWRxxR, which is perfectly conserved in all high confidence HV1 genes. Replacing Trp207 in human HV1 (hHV1) with Ala, Ser, or Phe facilitated gating, accelerating channel opening by 100-fold, and closing by 30-fold. Mutant channels opened at more negative voltages than wild-type (WT) channels, indicating that in WT channels, Trp favors a closed state. The Arrhenius activation energy, Ea, for channel opening decreased to 22 kcal/mol from 30–38 kcal/mol for WT, confirming that Trp207 establishes the major energy barrier between closed and open hHV1. Cation–π interaction between Trp207 and Arg211 evidently latches the channel closed. Trp207 mutants lost proton selectivity at pHo >8.0. Finally, gating that depends on the transmembrane pH gradient (ΔpH-dependent gating), a universal feature of HV1 that is essential to its biological functions, was compromised. In the WT hHV1, ΔpH-dependent gating is shown to saturate above pHi or pHo 8, consistent with a single pH sensor with alternating access to internal and external solutions. However, saturation occurred independently of ΔpH, indicating the existence of distinct internal and external pH sensors. In Trp207 mutants, ΔpH-dependent gating saturated at lower pHo but not at lower pHi. That Trp207 mutation selectively alters pHo sensing further supports the existence of distinct internal and external pH sensors. Analogous mutations in HV1 from the unicellular species Karlodinium veneficum and Emiliania huxleyi produced generally similar consequences. Saturation of ΔpH-dependent gating occurred at the same pHo and pHi in HV1 of all three species, suggesting that the same or similar group(s) is involved in pH sensing. Therefore, Trp enables four characteristic properties: slow channel opening, highly temperature-dependent gating kinetics, proton selectivity, and ΔpH-dependent gating.

scholarly journals Laser-Induced Biochar Formation through 355 nm Pulsed Laser Irradiation of Wood, and Application to Eco-Friendly pH Sensors

Nanomaterials ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1904
Author(s):  
Sung-Yeob Jeong ◽  
Chan-Woo Lee ◽  
Jun-Uk Lee ◽  
Yong-Won Ma ◽  
Bo-Sung Shin
Keyword(s):  
Laser Irradiation ◽  
Agricultural Land ◽  
Ph Sensor ◽  
Pulsed Laser ◽  
Agricultural Products ◽  
Organic Polymer ◽  
Ph Sensing ◽  
Ph Sensors ◽  
Linear Change ◽  
Pulsed Laser Irradiation

Due to the limited availability of agricultural land, pH sensing is becoming more and more important these days to produce efficient agricultural products. Therefore, to fabricate eco-friendly and disposable sensors, the black carbon, which is called biochar, is formed by irradiation of a UV pulsed laser having a wavelength of 355 nm onto wood and applying the resulting material as a pH sensor. The surfaces of three types of wood (beech, cork oak, and ash) were converted to the graphitic structure after UV laser irradiation; their morphologies were investigated. In addition, since the content of lignin, an organic polymer, is different for each wood, optimal laser irradiation conditions (laser fluence) needed to form these woods into pH sensors were considered. Depending on the degree of oil-like material generated after laser irradiation, a disposable pH sensor that can be used from one to three times is fabricated; due to the environmental characteristics of wood and biochar, the sensor shows high availability in that it can be easily discarded after use on agricultural land. After that, it can be used as filter in soil. Our wood-based pH sensor sensitively measures sequential changes from pH 4 to pH 10 and shows a very linear change of △R/R, indicating its potential for use in agriculture.

scholarly journals TiO2 Nano Flowers Based EGFET Sensor for pH Sensing

Coatings ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 251
Author(s):  
Chih-Chiang Yang ◽  
Kuan-Yu Chen ◽  
Yan-Kuin Su
Keyword(s):  
Ph Value ◽  
Ph Sensor ◽  
High Sensitivity ◽  
Experimental Result ◽  
Ph Sensing ◽  
Voltage Reference ◽  
Ph Sensors ◽  
Oxide Substrate ◽  
Ph Range ◽  
The Relationship

In this study, pH sensors were successfully fabricated on a fluorine-doped tin oxide substrate and grown via hydrothermal methods for 8 h for pH sensing characteristics. The morphology was obtained by high-resolution scanning electron microscopy and showed randomly oriented flower-like nanostructures. The TiO2 nanoflower pH sensors were measured over a pH range of 2–12. Results showed a high sensitivity of the TiO2 nano-flowers pH sensor, 2.7 (μA)1/2/pH, and a linear relationship between IDS and pH (regression of 0.9991). The relationship between voltage reference and pH displayed a sensitivity of a 46 mV/pH and a linear regression of 0.9989. The experimental result indicated that a flower-like TiO2 nanostructure extended gate field effect transistor (EGFET) pH sensor effectively detected the pH value.

scholarly journals Near-Infrared pH Sensor Based on a SPEEK–Polyaniline Polyelectrolyte Complex Membrane

Proceedings ◽  
2018 ◽  
Vol 3 (1) ◽  
pp. 11 ◽  
Author(s):  
Nedal Y. Abu-Thabit
Keyword(s):  
Polyelectrolyte Complex ◽  
Near Infrared ◽  
Response Times ◽  
Oxidative Polymerization ◽  
Ph Sensor ◽  
Ph Sensing ◽  
Ph Values ◽  
Sensing Applications ◽  
Ph Range ◽  
Speek Membrane

A polyelectrolyte complex (PEC) membrane based on sulfonated poly (ether ether ketone) and polyaniline (SPEEK-PANI) was developed for pH sensing applications. Aniline was polymerized in the presence of the SPEEK membrane by using in situ chemical oxidative polymerization to yield an ionically crosslinked SPEEK-PANI membrane. The fabricated membrane exhibited sensitivity in the physiological pH range of 2–8. The PEC membrane pH sensor showed good absorption properties in the near-infrared region (NIR). The membrane showed fast response during a de-doping process (≈90 s), while longer response times are essential for doping processes from the alkaline/neutral pH region to the acidic pH region, which is attributed to the presence of highly acidic sulfonic acid groups with a high buffering capacity in the PEC membrane. The SPEEK-PANI membrane exhibited slightly higher water uptake compared to the neat SPEEK membrane. The membrane exhibited good stability, as it was stored in 1M HCl solution for more than 2 years without physical or visual deterioration. A preconditioning step in 1M HCl ensured that the results were reproducible and allows the pH sensor to be used repeatedly. The PEC sensor membranes are suitable for applications that start at low pH values and move upwards to higher pH values in the 2–8 pH range.

scholarly journals Graphene Channel Liquid Container Field Effect Transistor as pH Sensor

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Xin Li ◽  
Junjie Shi ◽  
Junchao Pang ◽  
Weihua Liu ◽  
Hongzhong Liu ◽  
...  
Keyword(s):  
Field Effect ◽  
Field Effect Transistor ◽  
Ph Value ◽  
Ph Sensor ◽  
Drain Current ◽  
Fast Response ◽  
Monolayer Graphene ◽  
Ph Sensing ◽  
Order Of Magnitude ◽  
Effect Transistor

Graphene channel liquid container field effect transistor pH sensor with interdigital microtrench for liquid ion testing is presented. Growth morphology and pH sensing property of continuous few-layer graphene (FLG) and quasi-continuous monolayer graphene (MG) channels are compared. The experiment results show that the source-to-drain current of the graphene channel FET has a significant and fast response after adsorption of the measured molecule and ion at the room temperature; at the same time, the FLG response time is less than 4 s. The resolution of MG (0.01) on pH value is one order of magnitude higher than that of FLG (0.1). The reason is that with fewer defects, the MG is more likely to adsorb measured molecule and ion, and the molecules and ions can make the transport property change. The output sensitivities of MG are from 34.5% to 57.4% when the pH value is between 7 and 8, while sensitivity of FLG is 4.75% when thepH=7. The sensor fabrication combines traditional silicon technique and flexible electronic technology and provides an easy way to develop graphene-based electrolyte gas sensor or even biological sensors.

Development of the University of Idaho Parallel Hybrid FutureTruck

2003 ◽  
Author(s):  
Dan Gerbus ◽  
Douglas Welling ◽  
Scott Anderson ◽  
Frank Albrecht ◽  
Edwin Odom
Keyword(s):  
Parallel Hybrid ◽  
The University ◽  
University Of Idaho

scholarly journals A Transmembrane Histidine Kinase Functions as a pH Sensor

Biomolecules ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1183
Author(s):  
Ana Bortolotti ◽  
Daniela Belén Vazquez ◽  
Juan Cruz Almada ◽  
Maria Eugenia Inda ◽  
Salvador Iván Drusin ◽  
...  
Keyword(s):  
Histidine Kinase ◽  
Unsaturated Fatty Acids ◽  
Catalytic Domain ◽  
Ph Sensor ◽  
Alpha Helix ◽  
Acid Synthesis ◽  
Membrane Lipid ◽  
Ph Sensing ◽  
Salt Bridges ◽  
Arginine Residues

The two-component system DesK-DesR regulates the synthesis of unsaturated fatty acids in the soil bacteria Bacillus subtilis. This system is activated at low temperature and maintains membrane lipid fluidity upon temperature variations. Here, we found that DesK—the transmembrane histidine kinase—also responds to pH and studied the mechanism of pH sensing. We propose that a helix linking the transmembrane region with the cytoplasmic catalytic domain is involved in pH sensing. This helix contains several glutamate, lysine, and arginine residues At neutral pH, the linker forms an alpha helix that is stabilized by hydrogen bonds in the i, i + 4 register and thus favors the kinase state. At low pH, protonation of glutamate residues breaks salt bridges, which results in helix destabilization and interruption of signaling. This mechanism inhibits unsaturated fatty acid synthesis and rigidifies the membrane when Bacillus grows in acidic conditions.

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