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 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 Valve-Actuator-Integrated Reference Electrode for an Ultra-Long-Life Rumen pH Sensor

Sensors ◽  
2020 ◽  
Vol 20 (5) ◽  
pp. 1249
Author(s):  
Shogo Higuchi ◽  
Hironao Okada ◽  
Seiichi Takamatsu ◽  
Toshihiro Itoh
Keyword(s):  
Ph Monitoring ◽  
Ph Sensor ◽  
Reference Electrode ◽  
Ph Sensors ◽  
Liquid Junction ◽  
Reference Electrodes ◽  
Potential Measurement ◽  
Rumen Ph ◽  
Long Life ◽  
Intermittent Measurement

We demonstrated a newly developed Ag/AgCl reference electrode- with a valve-actuator for two years or longer rumen pH monitoring. Previous studies on pH sensors reported that the short lifetime of Ag/AgCl reference electrodes is caused by an outflow of internal electrolyte. We introduced a valve-actuator into a liquid junction to reduce the outflow by intermittent measurement. The results indicated that the potential change when switching the liquid junction was less than 0.5 mV and its response time was less than 0.083 s. In the 24-h potential measurement with the valve-actuator-integrated reference electrode (VAIRE), the valve was actuated once every hour, and the standard deviation of the potential was 0.29 mV. The lifetime of the VAIRE was estimated at 2.0 years calculating from an electrolyte outflow, which is significantly longer than that of conventional reference electrodes. A pH sensor using the VAIRE was estimated to operate for 2.0 years with the pH error ≤0.1, which meets the requirement of cows’ rumen pH monitoring.

scholarly journals EVALUATION ON THE EGFET PH SENSING PERFORMANCE OF SOL-GEL SPIN COATED TITANIUM DIOXIDE THIN FILM

2021 ◽  
Vol 83 (4) ◽  
pp. 119-125
Author(s):  
Muhammad AlHadi Zulkefle ◽  
Sukreen Hana Herman ◽  
Rohanieza Abdul Rahman ◽  
Khairul Aimi Yusof ◽  
Aimi Bazilah Rosli ◽  
...  
Keyword(s):  
Thin Film ◽  
Tio2 Thin Film ◽  
Drift Rate ◽  
Sol Gel ◽  
Ph Sensor ◽  
Ph Sensing ◽  
Coating Method ◽  
Effect Transistor ◽  
Sensing Membrane ◽  
Sensing Performance

For this study, TiO2 thin film was fabricated using the sol-gel spin coating method. The fabricated film was then applied as a sensing membrane in an extended gate field effect transistor (EGFET) pH sensor system. The pH sensing performance of the sol-gel spin-coated TiO2 was evaluated in terms of sensitivity, linearity, and hysteresis where the value obtained was 58.70 mV/pH, 0.9922, and 86.17 mV respectively. The drift rate of the sample when being measured for 12 consecutive hours was also determined where measurement in pH 4, pH 7, and pH 10 yield drift rate of 1.72 mV/h, 4.14 mV/h, and 6.05 mV/h respectively.  Besides that, the TiO2 was characterized for its thickness (24.32 nm) and surface roughness (5.129 nm). From the results obtained, it was found that sol-gel spin-coated TiO2 thin film with thickness between 20 - 29 nm will have high pH sensitivity (more than 50 mV/pH).

scholarly journals Ruthenium Oxide Nanorods as Potentiometric pH Sensor for Organs-On-Chip Purposes

Sensors ◽  
2018 ◽  
Vol 18 (9) ◽  
pp. 2901 ◽  
Author(s):  
Esther Tanumihardja ◽  
Wouter Olthuis ◽  
Albert van den Berg
Keyword(s):  
Ph Sensor ◽  
Ruthenium Oxide ◽  
Open Circuit ◽  
Ph Sensing ◽  
Ph Sensors ◽  
Oxide Nanorods ◽  
Order Of Magnitude ◽  
On Chip ◽  
Interfering Ions

A ruthenium oxide (RuOx) sensor for potentiometric pH sensing is currently being developed for organs-on-chip purposes. The sensor was fabricated from a Ru(OH)3 precursor, resulting in RuOx nanorods after heating. An open-circuit potential of the RuOx electrode showed a near-Nernstian response of −58.05 mV/pH, with good selectivity against potentially interfering ions (lithium, sulfate, chloride, and calcium ions). The preconditioned electrode (stored in liquid) had a long-term drift of −0.8 mV/h, and its response rate was less than 2 s. Sensitivity to oxygen was observed at an order of magnitude lower than other reported metal-oxide pH sensors. Together with miniaturizability, the RuOx pH sensor proves to be a suitable pH sensor for organs-on-chip studies.

A NOVEL pH SENSITIVITY OF SnO2 THIN FILM BASED EGFET PREPARED USING CHEMICAL BATH METHOD

2021 ◽  
pp. 2150074
Author(s):  
IMAD H. KADHIM ◽  
N. M. ABD-ALGHAFOUR
Keyword(s):  
Thin Film ◽  
Tin Dioxide ◽  
Ph Sensor ◽  
Morphological Properties ◽  
Sno2 Thin Film ◽  
Ph Sensing ◽  
X Ray Diffraction ◽  
Film Sensor ◽  
Rutile Structure ◽  
Si Substrates

Nanocrystalline (NC) tin dioxide (SnO2) thin film has been prepared using chemical bath method at low working temperature onto SiO2/Si substrates. The structural and morphological properties were studied through X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). The as-deposited thin film appeared with tetragonal rutile structure. The crystallization of SnO2 film was achieved when the film was exposed to anneal at [Formula: see text]C. NC SnO2 thin film was successfully utilized as an extended gate field-effect transistor (EGFET) pH sensing. NC SnO2 film based pH-EGFET sensor displayed a notable pH sensing performance, where the sensitivity and the linearity values are equal to 25.7 (mV/pH) and 0.8489 within 2–12 range consecutive. The NC SnO2 thin film sensor has shown good pH sensor stability and reliability; thus it can be considered the best choice for flexible and disposable biosensors.

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