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 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 A simplified methodology: pH sensing using an in situ fabricated Ir electrode under neutral conditions

2021 ◽  
Author(s):  
Yuqi Chen ◽  
Xiuting Li ◽  
Danlei Li ◽  
Christopher Batchelor-McAuley ◽  
Richard G. Compton
Keyword(s):  
Ph Sensor ◽  
Iridium Oxide ◽  
Ph Sensitive ◽  
Ph Sensing ◽  
Ph Dependency ◽  
Acidic Conditions ◽  
Ph Range ◽  
Neutral Conditions ◽  
Electrochemical Fabrication

AbstractHerein, a simplified fabrication method for the producing of a pH-sensitive iridium electrode is developed. The in situ electrochemical fabrication of an iridium oxide film is optimized and shown to be achievable under neutral conditions rather than the acidic conditions hitherto employed. The formation of a pH sensitive Ir(III/IV) hydrous film is confirmed via XPS. The amperometric pH-sensing properties of this electrochemically generated material were investigated using square wave voltammetry. In the pH range 2–13, the iridium oxide redox signal has a pH dependency of 86.1 ± 1.1 mV per pH unit for midpoint potentials with uncertainties being ± 0.01–0.05 pH. Finally, the newly developed pH sensor was used to measure the pH of a natural water sample with excellent results as compared to a conventional glass pH probe.

scholarly journals A Compact Ultrawideband Antenna Based on Hexagonal Split-Ring Resonator for pH Sensor Application

Sensors ◽  
2018 ◽  
Vol 18 (9) ◽  
pp. 2959 ◽  
Author(s):  
Mohammad Islam ◽  
Farhad Ashraf ◽  
Touhidul Alam ◽  
Norbahiah Misran ◽  
Kamarulzaman Mat
Keyword(s):  
Ring Resonator ◽  
Coupling Effect ◽  
Ph Sensor ◽  
Split Ring Resonator ◽  
Strip Line ◽  
Ph Sensing ◽  
Uwb Antenna ◽  
Split Ring ◽  
Electrical Length ◽  
Sensing Applications

A compact ultrawideband (UWB) antenna based on a hexagonal split-ring resonator (HSRR) is presented in this paper for sensing the pH factor. The modified HSRR is a new concept regarding the conventional square split-ring resonator (SSRR). Two HSRRs are interconnected with a strip line and a split in one HSRR is introduced to increase the electrical length and coupling effect. The presented UWB antenna consists of three unit cells on top of the radiating patch element. This combination of UWB antenna and HSRR gives double-negative characteristics which increase the sensitivity of the UWB antenna for the pH sensor. The proposed ultrawideband antenna metamaterial sensor was designed and fabricated on FR-4 substrate. The electrical length of the proposed metamaterial antenna sensor is 0.238 × 0.194 × 0.016 λ, where λ is the lowest frequency of 3 GHz. The fractional bandwidth and bandwidth dimension ratio were achieved with the metamaterial-inspired antenna as 146.91% and 3183.05, respectively. The operating frequency of this antenna sensor covers the bandwidth of 17 GHz, starting from 3 to 20 GHz with a realized gain of 3.88 dB. The proposed HSRR-based ultrawideband antenna sensor is found to reach high gain and bandwidth while maintaining the smallest electrical size, a highly desired property for pH-sensing applications.

Evaluation of Acridine in Nafion as a Fluorescence-Lifetime-Based pH Sensor

2003 ◽  
Vol 57 (1) ◽  
pp. 73-79 ◽  
Author(s):  
Alan G. Ryder ◽  
Sarah Power ◽  
Thomas J. Glynn
Keyword(s):  
Excited State ◽  
Fluorescence Lifetime ◽  
Light Emitting Diode ◽  
Ph Sensor ◽  
Average Lifetime ◽  
Ph Sensing ◽  
Light Emitting ◽  
Ph Response ◽  
Ph Values ◽  
The Impact

We report a novel fluorescence-lifetime-based pH sensing method that utilizes acridine incorporated into Nafion (AcNaf) as the fluorescent indicator. The AcNaf sensor is excited using a 380 nm light emitting diode (LED) and the fluorescence lifetimes are measured at 450 and 500 nm. The fluorescence behavior of acridine as a function of pH in aqueous phosphate buffers and incorporated into the Nafion membrane has been investigated. The results show that incorporating acridine into Nafion changes the apparent ground-state pKa from ∼5.45 to ∼9, while the apparent excited-state pKa* is only slightly changed (∼9.4 in 0.1 M phosphate buffer). The AcNaf film shows a good pH response with a change in average lifetime of ∼19 ns (at an emission wavelength of 450 nm) over the pH 8 to 10 range. We also show that excited-state protonation does not occur in the AcNaf sensor film and that chloride quenching cannot occur because of the permselective nature of Nafion. We also discuss how the unique structure of Nafion affects the fluorescence behavior of acridine at various pH values and examine the impact of buffer concentration on apparent pKa and pH sensing ability.

scholarly journals Optical pH sensor based on polyelectrolyte complex (PEC) pectin-chitosan/methanol anthocyanin extract of Catharanthus roseus for a new optical urea biosensor development

2021 ◽  
Vol 21 (3) ◽  
pp. 135-141
Author(s):  
NURHAYATI NURHAYATI ◽  
EKA SAFITRI ◽  
KHAIRI SUHUD ◽  
NAZARUDDIN NAZARUDDIN ◽  
BINAWATI GINTING ◽  
...  
Keyword(s):  
Catharanthus Roseus ◽  
Phosphate Buffer ◽  
Polyelectrolyte Complex ◽  
Ph Sensor ◽  
Total Phenolic ◽  
Buffer Solution ◽  
Good Linearity ◽  
Relative Standard ◽  
Ph Range ◽  
Optical Ph Sensor

Construction of optical pH sensor as a new platform optical urea biosensor based on polyelectrolyte complex (PEC) pectin-chitosan membrane and total phenolic (anthocyanin) of Tapak Dara flower (Catharanthus roseus) has been successfully carried out. The anthocyanin was extracted by a maceration method for 72 hours using methanol, and a total extract yield was 21.56% or 1.803 mg/L. Flavonoid and phenol tests showed positive results indicated by the formation of red and black colours. The anthocyanins showed maximum absorption at 578 nm for phosphate buffer and 575 nm for tris HCl buffer solution. The sensor fabrication was performed using a mixture of pectin and chitosan solutions with a ratio of 3:7. The anthocyanin was mixed into the solution with various concentrations. The sensor has an optimum sensitivity at the anthocyanin concentration of 0.05 mg/L (phosphate buffer) in the pH range of 7.0-9.5 and 0.025 mg/L (Tris HCl buffer) with a narrower pH range of 6.0-7.5. This sensor produced higher sensitivity, a wider linear range, and good linearity when it was exposed in 0.03M PBS. Reproducibility test with a relative standard deviation percentage (% RSD) was 9.20. The sensor showed a stable response after 5 minutes exposed to PBS solution, and it can be used to measure pH within the 20th day. The optimized optical pH sensor has been successfully developed as a urea optical biosensor by immobilizing urease on its surface. The biosensor showed a linear response in a series of 10-1-10-10 M urea concentrations and has good linearity.

Investigation of the Range of a Plastic pH Sensor Based on a Dibasic Ionophore

1992 ◽  
Vol 45 (2) ◽  
pp. 435 ◽  
Author(s):  
TJ Cardwell ◽  
RW Cattrall ◽  
LW Deady ◽  
KA Murphy
Keyword(s):  
Positive Charge ◽  
Ph Sensor ◽  
Low Ph ◽  
Membrane Electrode ◽  
Neutral Carrier ◽  
Ph Values ◽  
Response Range ◽  
Ph Scale ◽  
Ph Range ◽  
Sensitive Membrane

A study is reported of the use of a neutral carrier reagent containing two nitrogen atoms with very different basicities in a pH-sensitive membrane electrode with a view to obtaining a broad response range. This electrode responds well in the pH region of 6-12 but suffers anion interference in the region of pH 2-6. A study is included of the effect of adding various amounts of potassium tetrakis(4-chloropheny1)borate as an anion suppressing reagent to the membrane in order to reduce the anion interference at low pH values. The conclusion is drawn that an extension to the working pH range is not possible with this approach unless controlled amounts of anion suppressing reagent can be provided to approximately balance the positive charge of the carrier in each region of the pH scale.

scholarly journals Study and Optimization of Self-Assembled Polymeric Multilayer Structures with Neutral Red for pH Sensing Applications

2008 ◽  
Vol 2008 ◽  
pp. 1-7 ◽  
Author(s):  
Javier Goicoechea ◽  
Francisco J. Arregui ◽  
Jesus M. Corres ◽  
Ignacio R. Matias
Keyword(s):  
Optical Sensors ◽  
Response Times ◽  
Neutral Red ◽  
Layer By Layer ◽  
Ph Sensing ◽  
Force Microscopy ◽  
Sensor Applications ◽  
Sensing Applications ◽  
Lbl Films ◽  
Self Assembled

The characterization of nanostructured thin films is critical in the design and fabrication of optical sensors. Particularly, this work is a detailed study of the properties of layer-by-layer electrostatic self-assembled multilayer (LbL) structures fabricated using poly(allylamine hydrochloride) (PAH) and Neutral Red (NR) as cations, and poly(acrylic acid) (PAA) as polyanion. These LbL films, due to the colorimetric properties of the NR, are suitable for sensor applications such as pH sensing in the physiological range. In the (PAH+NR/PAA) LbL structure, it has been observed a very important influence of the pH of the solutions in the properties of the resultant films. Different techniques such as spectroscopy and atomic force microscopy (AFM) are combined to characterize the films, and the results are analyzed showing coherence with previous works. The LbL structure is finally optimized and dramatically improved nanostructured films were fabricated, showing good sensing properties, short response times, and good stability.

Novel polyelectrolyte complex between chitosan and poly(2-acryloylamido-2-methylpropanesulfonic acid-coacrylic acid)

e-Polymers ◽  
2003 ◽  
Vol 3 (1) ◽  
Author(s):  
Dilyana Paneva ◽  
Olya Stoilova ◽  
Nevena Manolova ◽  
Iliya Rashkov
Keyword(s):  
Polyelectrolyte Complex ◽  
Ph Value ◽  
Trichoderma Viride ◽  
Soil Fungus ◽  
Copolymer Composition ◽  
Chitosan Beads ◽  
Ph Values ◽  
Complex Forms ◽  
Ph Range ◽  
Stoichiometric Complex

Abstract A novel polyelectrolyte complex between chitosan and copolymers of 2- acryloylamido-2-methylpropanesulfonic acid (AMPS) and acrylic acid (AA) has been prepared. The formation of the complex has been studied viscometrically, gravimetrically and turbidimetrically in the pH range from 1.2 to 5.8. The stoichiometry and the yield of the complex depend on the copolymer composition and on the pH value of the medium. In the case of copolymers with low content of AMPS units the complexes are enriched in copolymer when formed in the pH range from 1.2 to 4.8. In this pH region mainly AMPS units take part in complex formation. A stoichiometric complex forms only at higher pH values due to the increased number of complexable carboxylate ions of AA units. The stoichiometry of the complexes prepared from copolymers with higher content of AMPS units is close to equimolar and is less sensitive to pH. The obtained complexes are stable up to pH 8. It has been shown that chitosan once included in the complexes remains degradable under the action of a crude enzyme complex produced by the soil fungus Trichoderma viride. The rate of the enzymatic hydrolysis decreases in the order chitosan/PAA > chitosan/P(AMPS-co-AA) > chitosan/PAMPS. Tests on the proliferation of T. viride embedded in chitosan beads have shown that coating the beads with chitosan/P(AMPS-co-AA) complex does not hamper the development of the microorganisms.

scholarly journals Optical pH Sensing in Milk: A Small Puzzle of Indicator Concentrations and the Best Detection Method

Chemosensors ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 177
Author(s):  
Olga Voskoboynikova ◽  
Aleksey Sukhanov ◽  
Axel Duerkop
Keyword(s):  
Optical Sensors ◽  
Detection Method ◽  
Ph Sensor ◽  
Photometric Determination ◽  
Bromocresol Purple ◽  
Ph Sensing ◽  
Ph Indicator ◽  
Ph Values ◽  
Sensor Membrane ◽  
Precision And Accuracy

Optical chemical sensors can yield distinctively different responses that are dependent on the method applied for readout and evaluation. We therefore present a comprehensive study on the pH determined non-continuously with optical sensors in real milk samples by either photometry or colorimetry (via the RGB-readout of digital images) compared to the pH values obtained electrochemically by potentiometry. Additionally, the photometric determination of pH was conducted with single-wavelength and a dual wavelength ratiometric evaluation of the absorbance. It was found that both the precision and accuracy of the pH determined by photometry benefit from lower concentrations of bromocresol purple, which served as the pH indicator inside the sensor membrane. A further improvement is obtained by the ratiometric evaluation of the photometric sensor response. The pH values obtained from the colorimetric evaluation, however, gain in precision and accuracy if a higher concentration of the indicator is immobilized inside the sensor membrane. This has a major impact on the future fabrication of optical pH sensor membranes because they can be better tuned to match to the most precise and accurate range of the planned detection method.

Psychophysiological Responses to Stress Related to Anxiety in Healthy Aging

2019 ◽  
Vol 33 (3) ◽  
pp. 188-197 ◽  
Author(s):  
Roberta Adorni ◽  
Agostino Brugnera ◽  
Alessia Gatti ◽  
Giorgio A. Tasca ◽  
Kaoru Sakatani ◽  
...  
Keyword(s):  
Healthy Aging ◽  
Near Infrared ◽  
Response Times ◽  
Cognitive Resources ◽  
Stressful Condition ◽  
Healthy Elderly ◽  
Situational Stress ◽  
Anxiety Response ◽  
Nirs Signal ◽  
Psychophysiological Correlates

Abstract. The aim of the study was to explore the effects of situational stress and anxiety in a group of healthy elderly, both in terms of psychophysiological correlates and cognitive performance. Eighteen participants ( Mage = 70 ± 6.3; range 60–85) were assessed for anxiety and were instructed to perform a computerized math task, under both a stressful and a control condition, while near-infrared spectroscopy (NIRS) signal and electrocardiography (ECG) were recorded. NIRS results evidenced an increased activation of right PFC during the entire procedure, even if effect sizes between left and right channels were larger during the experimental condition. The amount of right activation during the stressful condition was positively correlated with anxiety. Response times (RTs) were slower in more anxious than in less anxious individuals, both during the control and stressful conditions. Accuracy was lower in more anxious than in less anxious individuals, only during the stressful condition. Moreover, heart rate (HR) was not modulated by situational stress, nor by anxiety. Overall, the present study suggests that in healthy elderly, anxiety level has a significant impact on cerebral responses, and both on the amount of cognitive resources and the quality of performance in stressful situations.

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