Query: "pH sensor" OR "pH electrode"

Candidate papers:

abstract: Over the past years, to achieve better sensing performance, hafnium dioxide (HfO2) has been studied as an ion sensitive layer. In this work, thin layers of hafnium dioxide (HfO2) were used as pH sensitive membranes and were deposited by atomic layer deposition (ALD) process onto an electrolytic insulating semiconductor structure Al/Si/SiO2/HfO2 for the realization of a pH sensor. The thicknesses of the layer of the HfO2 studied in this work was 15, 19.5 and 39.9 nm. HfO2 thickness was controlled by ALD during the fabrication process. The sensitivity toward H+ was clearly higher when compared to other interfering ions such as potassium K+ lithium Li+ and sodium Na+ ions. Mott Schottky and electrochemical impedance spectroscopy (EIS) analyses were used to characterise and to investigate the pH sensitivity. This was recorded by Mott Schottky at 54.5, 51.1 and 49.2 mV/pH and by EIS at 5.86 p[H 1] 10.63 p[H 1] 12.72 p[H 1] for 15, 19.5 and 30 nm thickness of HfO2 ions sensitive layer, respectively. The developed pH sensor was highly sensitive and selective for H+ ions for the three thicknesses, 15, 19.5 and 39.9 nm, of HfO2 sensitive layer when compared to the other previously mentioned interferences. However, the pH sensor performances were better with 15 nm HfO2 thickness for the Mott Schottky technique, whilst for EIS analyses, the pH sensors were more sensitive at 39.9 nm HfO2 thickness.
author_names: Zina Fredj

Abdoullatif Baraket

Mounir Ben Ali

Nadia Zine

M Zabala

Joan R Bausells

Abdelhamid Elaissari

Nsikak U Benson

Nicole Jaffrezic-Renault

Abdelhamid Errachid
title: Capacitance Electrochemical pH Sensor Based on Different Hafnium Dioxide (HfO2) Thicknesses
year: 2021

abstract: A simple optical pH sensor based on immobilization, Dioscorea alata L. anthocyanin methanol extract, onto a pectin chitosan polyelectrolyte complex (pectin chitosan PEC) has been successfully fabricated. The optical pH sensor was manufactured as a membrane made of pectin chitosan PEC and the extracted anthocyanin. This sensor has the highest sensitivity of anthocyanin content at 0.025 mg/L in phosphate buffer and 0.0375 mg/L in citrate buffer. It also has good reproducibility with a relative standard deviation %RSD) of 7.7% and gives a stable response at time values greater than 5 min from exposure in a buffer solution, and the sensor can be utilized within five days from its synthesis. This optical pH sensor has been employed to determine saliva pH of people of different ages and showed no significant difference when compared to a potentiometric method.
author_names: Eka Safitri

Hani Humaira

Murniana Murniana

Nazaruddin Nazaruddin

Muhammad Iqhrammullah

Nor Diyana Md Sani

Chakavak Esmaeili

Susilawati Susilawati

Muhammad Mahathir

Salsabilla Latansa Nazaruddin
title: Optical pH Sensor Based on Immobilization Anthocyanin from Dioscorea alata L. onto Polyelectrolyte Complex Pectin Chitosan Membrane for a Determination Method of Salivary pH
venue: Polymers
year: 2021

abstract: The sensitivity of conventional ion sensitive field effect transistors is limited to the Nernst limit (59.14 mV/pH) In this study, we developed a pH sensor platform based on a coplanar gate AlGaN/GaN metal oxide semiconductor (MOS) high electron mobility transistor (HEMT) using the resistive coupling effect to overcome the Nernst limit. For resistive coupling, a coplanar gate comprising a control gate (CG) and a sensing gate (SG) was designed. We investigated the amplification of the pH sensitivity with the change in the magnitude of a resistance connected in series to each CG and SG via Silvaco TCAD simulations. In addition, a disposable extended gate was applied as a cost effective sensor platform that helped prevent damages due to direct exposure of the AlGaN/GaN MOS HEMT to chemical solutions. The pH sensor based on the coplanar gate AlGaN/GaN MOS HEMT exhibited a pH sensitivity considerably higher than the Nernst limit, dependent on the ratio of the series resistance connected to the CG and SG, as well as excellent reliability and stability with non ideal behavior. The pH sensor developed in this study is expected to be readily integrated with wide transmission bandwidth, high temperature, and high power electronics as a highly sensitive biosensor platform.
author_names: Seong-Kun Cho

Won-Ju Cho
title: High Sensitivity pH Sensor Based on Coplanar Gate AlGaN/GaN Metal Oxide Semiconductor High Electron Mobility Transistor
year: 2021

abstract: Development of a new pH sensor system, which is simple to prepare, sensitive, selective and workable with low volume, is demanding research in biomedical and environmental studies. In the literature, organic molecules like methylene blue, toluidine blue, hydroquinone, catechol, anthraquinone and polyaniline based redox probes have been widely used for this purpose. In general, these redox probes have easily interfered with common biochemicals such as dopamine, ascorbic acid, NADH, H2O2, cysteine, hydrazine, and some transition metal ions, etc. and in turn to marked potential and current drifts (pH false positive response) In this work, a highly redox active, stable and interference free redox polymer based on poly(4 chloroaniline) (PANI(4 Cl) modified graphitized mesoporous carbon (GMC) designated as GMC@PANI(4 Cl) has been prepared using 4 chloroaniline as a monomer in pH 7 phosphate buffer solution. The new redox polymer system showed a distinct redox peak at Eo' 0.15 V vs Ag/AgCl with a stable voltammetric response. Transmission electron microscope analysis of the redox polymer composite had shown adhesion of black polymeric solid due to polyaniline like the molecular system as a surface layer on the GMC material. The constructed calibration plot was linear in the pH window 2 11 with a slope and regression values 58 mV pH 1 and 0.9997, respectively. The GMC@PANI(4 Cl) modified electrode showed a sensitive and selective pH monitoring without any interference from the common biochemicals as listed above. As a practical application, pH sensing of commercial pH solutions, undiluted urine and saliva samples were demonstrated. Also, a three in one screen printed carbon modified GMC@PANI(4 Cl) was explored for pH monitoring of a bacterial (E.coli) growth, which showed a comparable response with the conventional pH electrode. A poly(4 chloroaniline) modified graphitized mesoporous carbon electrode has been prepared for an efficient redox active system for voltage current drifts and electrocatalytic response free differential pulse voltammetric pH sensor applications. A poly(4 chloroaniline) modified graphitized mesoporous carbon electrode has been prepared for an efficient redox active system for voltage current drifts and electrocatalytic response free differential pulse voltammetric pH sensor applications.
author_names: Sairaman Saikrithika

Annamalai Senthil Kumar
title: A selective voltammetric pH sensor using graphitized mesoporous carbon/polyaniline hybrid system
venue: Journal of Chemical Sciences
year: 2021

abstract: A temperature self calibrated potential of hydrogen (pH) sensor based on the single mode fiber tapered dual core photonic crystal fiber single mode fiber (SMF TDCPCF SMF) structure cascaded with a fiber Bragg grating (FBG) is proposed and demonstrated. The TDCPCF structure formed Mach Zehnder interferometer (MZI) is modified with a coating of graphene oxide/polyvinyl alcohol (GO/PVA) hybrid hydrogel to realize the measurement of pH, and the uncoated FBG is used to calibrate temperature. In our experiment, the sensitivity coefficient of 0.69 nm/pH with R2=0.99 and the hysteresis loss of less than 0.007 are achieved within the pH range from pH 4.00 to pH 9.85. The measured response time from pH 7.00 to pH 4.00, 6.00 and 9.85 are no higher than 10s. Moreover, the resonant wavelengths of MZI and FBG also exhibit good linear relationship with the temperature sensitivity coefficient of 0.15 nm/degC (R2=0.99) and 0.09 nm/degC (R2=0.97) respectively. It is demonstrated successfully that the proposed sensor has broad application prospects in the field of environmental monitoring, biological sensing and chemical analysis, due to the good performance of the temperature self calibrated pH monitoring, repeatability, linearity, response time and reversibility.
author_names: Ran Yan

Guofeng Sang

Bin Yin

Songhua Wu

Muguang Wang

Benran Hou

Ming-Cian Gao

Rong Chen

Han Yu
title: Temperature self calibrated pH sensor based on GO/PVA coated MZI cascading FBG.
venue: Optics express
year: 2021

abstract: Development of a biocompatible pH sensor is of importance in biomedical applications, particularly for in vivo measurement, providing necessary information for clinical diagnosis and treatment such as chronic wounds and foetal acidosis. Traditional pH indicator based optical sensors have problems of dye leaching and photobleaching that restrict their uses in long term monitoring. In this work, a dye free fibre optic pH sensor is proposed consisting of a U shape multimode optical fibre coated with a hybrid organic inorganic composite film. The film is formed by cross linking ethyl cellulose with a silica matrix at an optimised ethyl cellulose/silica molar ratio of 0.0065 via weakly interacted hydrogen bonding. This bonding is affected by hydrogen concentration (i.e. pH) in a solution resulting in a morphological change of the polymer aggregation presented in the silica matrix leading to refractive index change of the film. The developed sensor shows a reversible response to pH from 4.5 to 12.5 and exhibits linear correlation between transmitted light power and pH with a limit of agreement (LoA) between the sensor and a commercial probe of 0.2 pH. For a clinically important range of pH values between 6 and 8 the LoA is 0.1 pH. The sensor has low cross sensitivity to temperature as the maximum interpreted pH change attributed to the power change is 0.12 pH when the temperature changes from 21 degC to 39 degC. To demonstrate biomedical relevance, the sensor is used to monitor pH of human serum. An in house cytotoxicity assay is conducted with mouse fibroblast cell revealing that the film is not cytotoxic.
author_names: Zijuan Tang

David Gomez

Chenyang He

Serhiy Korposh

Stephen P Morgan

Ricardo Correia

Barrie R Hayes-Gill

Kerry Setchfield

Liangliang Liu
title: A U Shape Fibre Optic pH Sensor Based on Hydrogen Bonding of Ethyl Cellulose With a Sol Gel Matrix
venue: Journal of Lightwave Technology
year: 2021

abstract: Abstract Fluorescence intensity of carbon nanomaterials (CNMs) synthesized with ethanolamine hardly changed with pH value. Doping Zinc into CNMs improved optical properties of CNMs. On the one hand, the fluorescence quantum yield of CNMs increased, on the other hand, the fluorescence intensity of Zn doped CNMs decreased with pH value. Coupling Zn doped CNMs with ZnCdS quantum dots (QDs) as a dual emission system, the blue fluorescence intensity of CNMs (I450) decreased while the orange fluorescence intensity of QDs (I580) enhanced with pH value increasing. The ratio (I450/I580) varied linearly with pH value in the range of 1 9 and correlation coefficient (R2) was 0.991. Furthermore, using the system as a ratiometric fluorescence pH sensor to determine ascorbic acid, a good linear relationship (R2 0.998) was found when the concentration of ascorbic acid ranged from 0 1600 mM and limit of detection (LOD) was as low as 0.082 mM.
author_names: Yinyin Chen

Xianxiang Wang
title: New properties of carbon nanomaterials through zinc doping and application as a ratiometric fluorescence pH sensor
year: 2021

abstract: This paper describes a pH sensor for soil monitoring that is composed of fully biodegradable materials in the soil. Our biodegradable pH sensor is composed of only two key elements: One is a magnesium electromagnetic antenna that dissolves in water, and the other is a protection layer of hydroxyapatite that decomposes in response to pH. This sensor works as an electromagnetic split ring resonator (metamaterial) that reflects electromagnetic waves with specific frequency in GHz band, enabling in wireless remote sensing without any electric circuits or batteries. We demonstrated wireless pH detection of soil for aiming to realize an environmentally friendly monitoring sensor that does not require collection after installation.
author_names: Katsutoshi Hori

Ayaka Inami

Tetsuo Kan

Hiroaki Onoe
title: Split Ring Shaped Biodegradable pH Sensor for Wireless and Battery Free Monitoring of Agricultural Fields
venue: 2021 21st International Conference on Solid State Sensors, Actuators and Microsystems (Transducers)
year: 2021

abstract: This paper presents an analytical model of AlGaN/GaN MOS HEMT based pH sensor for the first time to determine pH of different electrolyte solutions. Gouy chapman stern model has been used to calculate the surface charge density. The results obtained using analytical model have been verified and show good agreement with the simulated results. Cavity length, thickness of AlGaN barrier layer and Al composition have been optimized to improve the sensitivity of the device. It has been observed that the drain current and threshold voltage decreases with increase in pH of the electrolytic solutions. Proposed AlGaN/GaN MOS HEMT sensor demonstrate a quick response to the pH changes. The maximum drain on sensitivity of the device is 132mA/mm pH. Surface potential and threshold voltage sensitivity of 0.95mV/pH and 950mV/pH respectively have been obtained which is much higher than the Nernstian limit(59.2mV/pH)
author_names: Praveen Pal

Yogesh Pratap

Mridula Gupta

Sneha Kabra
title: Analytical Modeling and Simulation of AlGaN/GaN MOS HEMT for High Sensitive pH Sensor
venue: IEEE Sensors Journal
year: 2021

abstract: To improve the stability and sensitivity of pH sensors based on AlGaN/GaN high electron mobility transistors (HEMTs) we proposed a modified sensing structure by integrating a reference HEMT device. This structural pH sensor exhibits a typical Nernstian behavior with a sensitivity of 54.38 mV/pH, which is higher than the value of 49.43mV/pH derived from the AlGaN/GaN HEMT based sensor without integrating the reference HEMTs device. Furthermore, the stability of the new structural sensor is enhanced by approximately 19.2% in comparison with that of its traditional counterpart. The improved performances are analyzed using an electrical double layer model together with an equivalent circuit model, and we find that the new sensor structure has a larger capacitor and exhibits a better rectification effect, hence decreasing the electrical noise and enhancing the stability of the testing signal. Meanwhile, the new sensor structure displays a smaller equivalent resistance and results in a larger available output current, hence exhibiting a higher sensitivity.
author_names: Zi Li Xie

Yanli Liu

Jianming Lei

Hui Guo

Quan Dai

Jeong-Gil Kim

Seung-Hyeon Kang

C -H Won

Jung-Hee Lee

Dunjun Chen

Rong Zhang

Youdou Zheng
title: Enhanced Stability and Sensitivity of AlGaN/GaN HEMTs pH Sensor by Reference Device
venue: IEEE Sensors Journal
year: 2021