Response Time Of Electrode Research Articles

Estimation of trace element of strontium ion using ion selective electrode based on a ceramic cordierite nanoparticle in some vegetarian foods

The development of an ion-selective electrode for the potentiometric measurement of strontium ions using ceramic nanoparticles (cordierite) as an ionophore was a concern in this study. The nano cordierite (Mg2Al4Si5O18) was synthesized by sol–gel method and subsequently characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) analysis, transmission electron microscope (TEM), scanning electron microscope (SEM) with EDAX unit and contact angle. The XRD results confirm the purity and crystalline structure of nanoparticles. The average crystallite size and particle size were studied by Debye-Scherrer equation, TEM, and SEM and it is found to be 16.9 and 29.29 nm which is a mesoporous structure. Cordierite nanoparticles were used to accelerate the electron transfer which refers to the extensive surface area, electrical characteristics, porous design, and nanoscale dimension. The carbon paste electrode optimization was done to study the potentiometric performance of Sr(II) ion detection. The electrode composition was 5.0 % synthetic ionophere, 28.9 % tricresylphosphate (TCP), and 65.8 % graphite powder (w/w). Stable potentiometric behavior was shown in the concentration range 1.0 × 10−6 −1.0 × 10−2 mol/L (R2 = 0.998). The electrode detection limit and response time were 5.0 × 10−7 mol/L and 6 s, respectively. As well as the electrode showed selectivity towards the Sr(II) ion in the vicinity of certain cation species. Also, it was performed without any variations in response within the pH range of 3–8. Additionally, Sr(II) ion determination was detected in some real samples (plant origin) such as legumes (kidney bean), cereals (wheat), leafy vegetables (cabbage), stems (onion), roots (carrot), fruits (tomatoes) and nuts (almond) with high recoveries and reproducibility through around 72 days. Subsequently, the outcome was assessed against the ICP technique's superior performance.

Fast chromium determination in pharmaceutical tablets by using electrochemical sensors: Preparation and comparison

In the present paper, three electrodes were prepared with the aim of detecting chromium (III) in pharmaceutical tablets and comparing their capabilities and efficiency. At first, N-(pyridine-2-ylcarbamothioyl) benzamide (NP2YCTB) was synthesized and characterized by 1H NMR, FTIR, and 13C NMR spectroscopy methods. Then, it is used as a sensing material to prepare three types of chromium potentiometry sensors including solid-state electrodes (SSE), coated wire electrodes (CWE) as asymmetric electrodes, and liquid membrane electrodes (LME) as symmetric electrodes. The responses of all electrodes were Nernstian. Field-emission scanning electron microscopy was utilized to investigate the liquid membrane morphology. The presence of chromium (III) in the membrane was proved using Energy-dispersive X-ray spectroscopy and the coordination of NP2YCTB heteroatoms with chromium (III) was confirmed by Fourier transform infrared spectroscopy. The limit of detection for SSE (3 × 10−9 mol/L) was enhanced compared with LME (7 × 10−6 mol/L) and CWE (3 × 10−7 mol/L). The response time of electrodes was very short so it was about 5–6 s for LME and CWE and 5–8 s for SSE. The sensors were used for the potentiometric determination of chromium (III) in pharmaceutical tablets and in the potentiometric titration of it with EDTA.

Detection of antibodies against SARS-CoV-2 Spike protein by screen-printed carbon electrodes modified by colloidal gold nanoparticles

In this work, electrochemical bioanalytical systems for the determination of antibodies against the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Spike protein (anti-rS) is reported. Environmentally friendly chemicals were applied in the synthesis of gold nanoparticles (AuNPs). The AuNPs were integrated onto the screen-printed carbon electrodes (SPE), and the biological recognition part was based on recombinant SARS-CoV-2 Spike protein (rS), which during the immobilization was cross-linked by glutaraldehyde. Immobilized rS protein based biological recognition part enabled selective recognition of anti-rS antibodies. The current flux of AuNPs reduction (at +200 mV) in a pure phosphate buffer (PB) was employed as the transduction signal. It has been reported that the formation of anti-rS layers on the surface of AuNPs delays the electrode response time (ts), tracked at the current flux density values of 80 μA cm−2. Using the AuNP-modified SPE, we demonstrated a rapid anti-rS detection within a detection limit of 2 ng mL−1 (0.125 binding antibody units mL−1, 17 pM). This system can be applied to track the response of immune system towards SARS-CoV-2 infection and monitoring of Coronavirus Disease 2019 (COVID-19).

Design and experimental investigation of interdigitated electrode architecture for tunable liquid crystal-based metasurfaces with rapid responses

In this paper, an interdigitated electrode architecture is investigated, which can be used to tune the permittivity of liquid crystal (LC) in metasurfaces with rapid responses. The interdigitated electrodes are composed of two groups of cross-distributed comb grids, where external bias voltages can be applied to each group of comb grids. By continuously adjusting the bias voltages through the grids, the orientation of the liquid crystal molecules can be dynamically controlled due to the excited electrostatic field. Hence the permittivity of the LC and the electromagnetic responses of the metasurface can be tuned arbitrarily by the external biasing. Three kinds of interdigitated electrodes with different fitting ratios were developed to explore the working of the interdigitated electrode architecture. The response time of these interdigitated electrodes and their influence on frequency tunability were analyzed in detail. The measured absorption spectra of interdigitated electrodes with 7, 9, and 11 grids per unit cell with identical periodicity indicate that the fill density of comb grids has a negligible effect on the frequency tunability. However, the fill density has a significant impact on the response time of the LC metamaterial in the interdigitated electrodes. Moreover, the response time was further reduced by 65% with the increase in the number of grids. The proposed architecture and its design provide new insight into developing tunable LC metasurfaces with rapid responses.

An Ion Selective Electrode Construction Based on Phosphomolybdic Acid for Atropine Sulfate Detection

AbstractThis study presents an attempt has been carried out to fabricate ion‐selective electrodes (ISEs) for the determination of Atropine sulfate (AT) in pharmaceutical formulas. Three plasticizers; namely, di‐n‐butyl phthalate (DBP), bis (2‐ethyl hexyl) phthalate (BEP), nitrobenzene (NB), and tetrahydrofuran (THF) were used in the fabrication of the three ion selective electrodes after incorporating into polyvinyl chloride (PVC) and symbolized as E1, E2, and E3, respectively. Beyond evaluation of the three ISEs, it has been confirmed that one with DBP experienced the most Nernstian behaviour. For the electrode of interest, the slope and detection limit are 55.02 mV/decade and 1.1×10−6 M, respectively. The linear range was 1.0×10−2–1.0×10−5 M (R2=0.9999) with recording 5 s and 45 days; sequentially, for the response time and shelf life of E1 electrode. The sensor has experienced high selectivity for atropine sulfate, verifying from the selectivity coefficient data for a number of potential interferences. The statistical analysis using t‐test and F‐test indicates the eligibility of constructed electrode for utilization in field of pharmaceutical analysis. A satisfactory accordance has been obtained between the proposed electrode for atropine sulfate and the standard method. This methodology is supposed to be applicable in quality control and even clinical diagnosis.

Green fluorescent protein-multi walled carbon nanotube based polymeric membrane electrode for bismuth ion detection

Developing a sensor that is selective only to the target metal type remains a major challenge. Polymeric membrane electrodes are versatile devices with exceptional analytical simplicity and are frequently used in environmental analysis. A novel polymeric membrane electrode (PME) was proposed for the determination of bismuth ions with high sensitivity. In an unconventional approach, Green Fluorescent Protein (GFP) was used as an ionophore in the fabrication of PME electrodes. GFP, a member of the fluorescent protein family, has emerged as biocompatible tools, especially for biomedical applications, bioimaging, intracellular monitoring, sensors, and optical devices, and has attracted great attention thanks to its unique advantages. In this study, a high performance compatible PME has been developed by solvent casting method integrating GFP doped elastomeric multi-walled carbon nanotubes (MCNTs) into conductive plasticized polyvinyl chloride (PVC). The high metal-binding affinity of GFP made these proteins potential ionophores in the PME structure. The morphological structures of the produced GFP-doped MWCNT were characterized by HRTEM. Potentiometric behaviors and performance of the produced bismuth selective PME are summarized for both analytical and real examples. The prepared electrode exhibited Nernstian behavior with a slope of 19 ± 1 mV and a low detection limit of 4.3 × 10−6 M, and the electrode response time was observed as <40–45 s.

Novel (E)−2-((1-(thiophen-2-yl)ethylidene)-amino) phenol Manganese(II) as an Ionophore Based on Thiocyanate-Selective Electrodes and Its Applications

Novel highly selective potentiometric sensor based on aquadichloro(E)−2-((1-(thiophen-2-yl)ethylidene)-amino)phenol manganese(II)trihydrate as an anion carrier. The thiocayanate electrode displayed a very high selectivity compared with others inorganic anions. Different sensors with plasticized PVC membranes have been investigated. The sensors construction containing different amounts of ionophore with and without additives. The pH over 3.5–6.5 range has been studied. Optimized membrane electrode included 66 mg PVC, 132 mg o-nitrophenyloctylether, 10 mol % tetrakis(trifluoromethyl)phenyl borate and 2% [Mn(C12H11NOS)(Cl2)(H2O)]· 3H2O. The optimized sensors exhibit Nernstian response for thiocyanate through a linear concentration ranging from (5 × 10−8 to 9.06 × 10−1 M) with a detection limit of 3 × 10−8 M and a slope of −57.7 mV decade−1, the measurement carried out in acetate buffer pH 4.7. The response time of electrode <10 s and the lifetime of the sensor more than 6 weeks. The proposed electrode was effectively utilized to estimation of thiocyanate in saliva sample, the results revealed a valid agreement with reference colorimetric method.

Çok Duvarlı Karbon Nanotüpler/Politiyofen Kompozit Kullanılarak Hazırlanan Amperometrik Glikoz Biyosensörü

In this study, multi-walled carbon nanotubes/polythiophene composite (MWCNTs/PTh) modified glassy carbon electrode was used for the amperometric detection of glucose. Glucose oxidase (GOx) was entrapped by a crosslinking agent on the MWCNTs/PTh composite film synthesized by electrochemical polymerization of thiophene onto MWCNTs. Characterization of composite film was achieved by cyclic voltammetry (CV), fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) techniques. The amperometric measurements of electrode was performed at +0.70V vs. SCE, which was the electrooxidation potential of enzymatically produced H2O2. The effects of thiophene amount in the composite, pH, temperature and substrate concentration were investigated on the response of enzyme electrode. Optimum pH was 7.0 at room temperature and the response time of enzyme electrode was 25 s. The upper limit of the linear working range was 4.85 mM glucose concentration. The limit of detection of sensor was calculated as 148 µM. The sensitivity of glucose biosensor was determined as 4.39 µA mM-1 cm-2. The value of apparent Michaelis-Menten constant (KMapp) was 1.68 mM according to the Lineweaver-Burk equation. The activation energy of this immobilized enzyme system was 88.92 kJ mol-1.

Imprinted-Zeolite-X-Based Sensor for Non-Enzymatic Detection of Blood Glucose by Potentiometry

The development of sensors based on imprinted zeolite X to detect blood glucose through potentiometry was performed. In this study, the sensor was made of a mixture of carbon paste and imprinted zeolite X. Zeolite X was synthesized using a sol–gel-hydrothermal method at a temperature of 100 °C with basic materials of NaAlO2, NaOH, TEOS, and distilled water. The characterization results of XRD showed the presence of specific peaks, which were confirmed with standard zeolite X. Imprinted zeolite X exhibited a 20 times greater adsorption capacity size, and an adsorption efficiency 3 times greater than that of zeolite X. This is thought to be due to the presence of a molecular template within it. The IZ–carbon paste electrode showed optimum performance due to a mass ratio of carbon, paraffin, and imprinted zeolite X of 12:7:1. The electrode performance was expressed by the Nernst factor value of 30 mV/decade, the measuring range of 10−4–10−2 M, the upper detection limit of 1.38 × 10−2 M, and the lower detection limit of 1.28 × 10−4 M, so this electrode can be used for glucose analysis with a normal concentration (70–110 mg/dL or equivalent to 3.8 × 10−3–6.1 × 10−3 M), as well as the glucose concentration of people with diabetes mellitus (&gt;200 mg/dL or about 10−2 M). This electrode showed precision values of 97.14–99.02%, accuracy values of 98.65–99.39%, and electrode response times of 10–13 s. The electrodes showed high stability for more than 5 weeks with 141 uses. The electrodes also showed high selectivity for glucose in the matrix of uric acid, urea, NaCl, and KCl. Therefore, its use as an alternative electrode for routine glucose analysis in the medical field is recommended.

A pH-dependent partial electrochemical exfoliation of highly oriented pyrolytic graphite for high areal capacitance electric double layer capacitor electrode

High electrolyte resistance severely limits the response time and energy efficiency of an electric double layer capacitor electrode. Vertically oriented graphene nanosheets (VOG) having open, straight channel morphology is a new, attractive morphology with low electrolyte resistance. While CVD remains the dominant synthesis method for VOG electrodes, electrochemical exfoliation of graphite, a facile, economical and scalable method for production of loose graphene flakes, can also provide a VOG electrode. Here we show, that the conditions of electrochemical exfoliation for producing VOG morphology is substantially different from using it to produce loose graphene flakes. In particular, a low pH solution leads to a better expansion of the graphite and substantially better VOG density while a high pH solution leads to the formation of loose graphene flakes. Sulfuric acid is better than other sulfate salt-based electrolyte solutions for the synthesis of a VOG electrode. The electrolyte concentration, exfoliation time, and current density also affect the electrode capacitance. The optimal process conditions provide a VOG electrode of areal capacitance 750 mF/cm2. A capacitor consisting of two identical VOG electrodes shows a volume capacitance density of 1.56 F cm−3 higher than most of the literature values for supercapacitors.

Enzyme-based ultrasensitive electrochemical biosensor using poly(l-aspartic acid)/MWCNT bio-nanocomposite for xanthine detection: A meat freshness marker

Sensitive and selective detection of xanthine (XA) in food industries is of notable importance for evaluating the meat freshness. A new and simple-to-prepare nano-biocomposite of multi-walled carbon nanotube (MWCNT) and poly(l-aspartic acid) (Poly(l-Asp)) film is prepared for the immobilization of xanthine oxidase (XO) on glassy carbon electrode (GCE). Electropolymerization of biocompatible polymer was performed by cyclic voltammetry (CV). Bio-analytical optimal experimental conditions such as percentage of MWCNT, immobilizing time of the enzyme, the response time of electrode and the value of pH were studied in detail. The fabrication process of the XO/Poly(l-Asp)/MWCNT/GCE electrode was pursued by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM). The developed biosensor was employed for the determination of xanthine in fish meat based on differential pulse voltammetry (DPV) method. DPV response was showed a linear range in the range of 0.001–0.004 μM and 0.005–50.0 μM, with a low detection limit of 3.5 × 10−4 μM and surprisingly high selectivity. Finally, the developed biosensor was successfully applied for xanthine determination in fish meat at different storage times.

A sensitive and selective non-enzymatic glucose sensor with hollow Ni-Al-Mn layered triple hydroxide nanocomposites modified Ni foam

Hollow Ni-Al-Mn triple layered hydroxide (HLTH) nanocomposite is used for developing a sensitive nonenzymatic electrochemical glucose sensor. Electrochemical studies of HLTH modified nickel foam (NF) possess a remarkable sensing activity towards glucose oxidation with a wide range of detection from 0.015 mM to 8 mM. The sensors show a superior sensitivity of 2.253 mA mM−1 cm−2 with a low glucose detection limit of 1.49 μM (S/N = 3). The fast response time of electrode is <3 s was mainly attributed to the combined effects of metal ions results in the enhanced electrical conductivity of material originating from abundant electroactive cites and stable structure. The application of sensor in glucose detection from human serum is also confirmed. HLTH possess an excellent selectivity of glucose over ascorbic acid and uric acid. The fabricated sensor confirmed the suitable stability, better reproducibility, and extreme sensitivity. The proposed material can be effectively used to detect glucose level in real time application.

A Novel Modified Carbon Paste Electrode for the Determination of Chromium(III) in Water

Two kinds of modified carbon paste electrodes for chromium(III) ion based on zeolite as ionophore were prepared. 3-Methylpyrazol-5-one was used as modifier in sensor 1. Sensor 1 exhibits a Nernstian response for Cr(III) ions over a wide concentration range from 1 × 10–6 to 1 × 10–2 M with a slope of 19.8 ± 0.1 mV/decade. Sensor 2 was modified by using chlorinated multiwalled carbon nanotubes. This sensor shows a Nernstian response for Cr(III) ions over a concentration range from 1 × 10–7 to 1 × 10–2 M with a slope of 19.74 ± 0.1 mV/decade. Some parameters were optimized for the two sensors, such as pH of solution, composition of membrane and response time of electrode. The sensors were successfully applied to direct determination of chromium(III) in water samples and as an indicator electrodes in potentiometric titration of Cr(III) with EDTA.

A novel potentiometric pH electrode based on sulfated natural Fe3O4 and analytical application in food samples

A novel solid state potentiometric pH electrode based on sulfated natural Fe3O4 silicone was fabricated. The optimum potentiometric performances such as Nernstian response, response time, selectivity, life-time and reproducibility of pH electrodes were investigated by using a computer-controlled potentiometric device. Moreover, the potentiometric performance of the solid state pH electrodes was studied with different mixtures sulfated natural Fe3O4, silicone and graphite powder. The best potentiometric behavior of proposed pH electrode was obtained with a composition of 20% (w/w) sulfated natural Fe3O4, 40% (w/w) graphite powder and 40% (w/w) silicone. The sub-Nernstian response for pH electrode was exhibited with a slope of 30.8 ± 1.4 mV/pH (r = 0.9963) from pH 2 to pH 12. In addition, the dynamic response time was found as 10 s in acidic medium and further the proposed pH electrode can be used for at least 1 year without any significant slope of the pH–potential curve. The selectivity coefficient of pH electrode was interpreted according to fixed interference method in the presences of Na+, Li+, K+, NH4+, SO42‒, CH3COO‒ and NO3‒ ions. The reproducibility of pH electrode was calculated in pH 4 and pH 6 phosphate buffers and it was found as 0.24 RSD (%) and 0.27 RSD (%) respectively. The proposed pH electrode was used to determine of pH in acid‒bases titration compared with glass pH electrode and is highly stable in corrosive systems including HF solution. Terminally, the pH value was successfully determined in some soft drinks and milk samples by proposed solid state pH electrode at 95% confidence level with satisfactory agreement compared with glass pH electrode.

A Sensitive Electrochemical Sensor for Rapid Determination of Mebeverine Hydrochloride and Metronidazole Benzoate Selective Molecular Imprinted Polymer in the PVC Membrane

By using precipitation polymerization, liquid electrodes of polymers imprinted with Mebeverine hydrochloride and metronidazole benzoate were created whereas the imprinted polymer (MIP) and non imprinted (NIP) polymers were prepared by using Mebeverine hydrochloride and Metronidazole benzoate qua a template. In the polymerization process, 2-Acrylamido-2-methyl-1-propane Sulphonic acid (AMPS) or 1-Vinylimidazole (VIZ) was used qua monomer, pentaerythritol triacrylate (PETRA) or Divinylbanzene (DVB) was used qua a cross-linker while benzoyl peroxide (BPO) was used as an initiator. The MIP membranes and the membranes of NIP were created by using Dibutyl Sebacate (DBS) and Tris(2-ethylhexyl)phosphate(TEHP) qua plasticizers in PVC matrix. The response time of the liquid electrodes was 1min. whereas their slopes and detection limits reached to 19.62 – 57.36 mV per decade and 1.2 x 10-6 – 2.0 x 10-5 M, respectively. Filling with standard solution of drug (0.1M), the liquid electrodes response -with suitable No.( selectivity for numerous of species - was suitable No.( since pH reached to 1.5 – 12. The developed electrodes were successfully applied for the analyte determination in preparation pharmaceutical sample without any time consuming pretreatment steps.

Enhancement of the Enzymatic Biosensor Response through Targeted Electrode Surface Roughness

The field of enzymatic biosensors applied to brain electrochemistry has rapidly expanded over the last few years, thanks in part to their excellent selectivity to specific target species. Much current research is therefore focused on enhancing the electrochemical signal, which often involves the detection of stoichiometric amounts of H2O2 formed as part of the enzyme mechanism. This opens the possibility of enhancing a biosensor's performance by facilitating the H2O2 oxidation signal through surface modification. Here, we investigate the impact of the roughness of the platinum surface on the biosensor response, where rougher platinum surfaces show greater activity for H2O2 oxidation, and therefore enhanced biosensor sensitivity. Through careful manipulation of the electrode surface roughness, we are able to show a significant improvement to the LOD when using a rougher electrode surface. Additionally, we have shown that this enhanced surface roughness has no detrimental effects toward the electrode response time. This suggests that surface roughness could be a simple and easy to implement means of enhancing the sensitivity of electrode-based enzymatic biosensors, and is an important factor to consider when studying other aspects of biosensor fabrication.

Large-scale layer-by-layer inkjet printing of flexible iridium-oxide based pH sensors

Metal oxide based pH sensors are used in various applications, especially when the conventional glass electrode is unsuitable due to its fragility or when the applications require disposable sensors, e.g. for biomedical, clinical or food process monitoring. Generally, such pH sensors are produced by thermal oxidation or electrochemical deposition, neither suited for mass production nor miniaturization. Herein, we report on the fabrication of reliable and sensitive pH sensors based on the nano-assembly of iridium oxide (IrOx) nanoparticles and polydiallyldimethylammonium (PDDA) polymer layers. Such potentiometric sensors were very reproducibly fabricated on a large-scale via a layer-by-layer inkjet printing (LbL IJP) methodology. The obtained results indicated the ability of the LbL IJP technique to easily manipulate the NP coverage by the number of printed bilayers, leading to a swift sensor optimization. Open-circuit potentials were recorded to evaluate the pH sensitivity, response time, and reproducibility of the pH electrodes, which exhibit a rapid, linear and near-Nernstian pH response of about 59mV/pH. Moreover, an RSD of 0.6% for five different electrodes from the same printing batch showed the excellent reproducibility of the IJP process with a correlation coefficient of 0.99 for all measurements. The insights gained in this study could be the basis for a new approach of developing scalable, patterned and flexible pH sensors with improved performance and a wide range of applications.

A non-enzymatic glucose sensor based on CuO-nanostructure modified carbon ceramic electrode

Mesoporous silica-graphite composite (SiO2/C-graphite) was synthesized by the sol-gel technique. The surface area (SBET=98.93m2/g), pore volume (0.30cm3/g) and pore size (12.16nm) were characterized by BET. The novelty of this work lays in the fabrication of material in which ceramic material (SiO2/C-graphite) was decorated with copper oxide (CuO) nanostructure. SEM images revealed material compactness without phase segregation and EDX mapping showed a homogenous structure. Pressed disk electrode fabricated with SiO2/C/CuO nanocomposite material was evaluated as an amperometric non-enzymatic glucose sensor in 0.1M NaOH solution. The linear response range, sensitivity, detection limit, and quantification limit were 0.02–20.0mmolL−1, 0.06μmolL−1, 472μA mmol−1L−1cm−2, and 0.76mmolL−1, respectively. The electrode response time is <1s with the addition of 0.02mmolL−1 glucose. The electrode is chemically stable, exhibits rapid and excellent sensitivity and does not show any interference from coexisting species present in the blood samples. The proposed sensor repeatability was assessed as 1.9% RSD for ten measurements of 13.0mmolL−1 glucose solution. The sensor tested to ascertain glucose in blood serum showed to be a promising tool for the future evolution of non-enzymatic glucose sensors.

Graphene-Enabled Electrodes for Electrocardiogram Monitoring.

The unique parameters of graphene (GN)—notably its considerable electron mobility, high surface area, and electrical conductivity—are bringing extensive attention into the wearable technologies. This work presents a novel graphene-based electrode for acquisition of electrocardiogram (ECG). The proposed electrode was fabricated by coating GN on top of a metallic layer of a Ag/AgCl electrode using a chemical vapour deposition (CVD) technique. To investigate the performance of the fabricated GN-based electrode, two types of electrodes were fabricated with different sizes to conduct the signal qualities and the skin-electrode contact impedance measurements. Performances of the GN-enabled electrodes were compared to the conventional Ag/AgCl electrodes in terms of ECG signal quality, skin–electrode contact impedance, signal-to-noise ratio (SNR), and response time. Experimental results showed the proposed GN-based electrodes produced better ECG signals, higher SNR (improved by 8%), and lower contact impedance (improved by 78%) values than conventional ECG electrodes.

A new approach for kLa determination by gassing‐out method in pneumatic bioreactors

AbstractBACKGROUNDDetermination of the volumetric oxygen transfer coefficient (kLa) is very important for bioreactor design and process analysis. Among all the methods available, the gassing‐out technique is one of the simplest and most widely used for this task. However, this method is very sensitive to the probe dynamics (due to delay effects), which can lead to inaccuracy in the kLa determination. This is especially pronounced for airlift bioreactors, where the circulation time affects the initial dynamics of the assay (a transient effect). In the present work, a new method for kLa determination is proposed.RESULTSValues of kLa and the electrode response time (τe) were determined experimentally, employing the traditional gassing‐out method and the method proposed here. The latter was shown to be reliable, easier to apply, and suitable for the simultaneous determination of kLa and electrode sensitivity (ke = 1/τe), without any need for additional assays.CONCLUSIONThe new method overcomes the effects of probe delay on kLa determination, making the procedure faster and simpler. © 2016 Society of Chemical Industry