Measurement Of Ion Concentration Research Articles

Wearable and Multiplexed Biosensors based on Oxide Field-Effect Transistors.

Wearable sensors designed for continuous, non-invasive monitoring of physicochemical signals are important for portable healthcare. Oxide field-effect transistor (FET)-type biosensors provide high sensitivity and scalability. However, they face challenges in mechanical flexibility, multiplexed sensing of different modules, and the absence of integrated on-site signal processing and wireless transmission functionalities for wearable sensing. In this work, a fully integrated wearable oxide FET-based biosensor array is developed to facilitate the multiplexed and simultaneous measurement of ion concentrations (H+, Na+, K+) and temperature. The FET-sensor array is achieved by utilizing a solution-processed ultrathin (≈6nm thick) In2O3 active channel layer, exhibiting high compatibility with standard semiconductor technology, good mechanical flexibility, high uniformity, and low operational voltage of 0.005V. This work provides an effective method to enable oxide FET-based biosensors for the fusion of multiplexed physicochemical information and wearable health monitoring applications.

Decoupling ion concentrations from effluent conductivity profiles in capacitive and battery electrode deionizations using an artificial intelligence model

Owing to its simplicity of measurement, effluent conductivity is one of the most studied factors in evaluations of desalination performance based on the ion concentrations in various ion adsorption processes such as capacitive deionization (CDI) or battery electrode deionization (BDI). However, this simple conversion from effluent conductivity to ion concentration is often incorrect, thereby necessitating a simpler method for performing real time measurements of effluent ion concentrations. In this study, a random forest (RF)-based artificial intelligence (AI) model was developed to address this shortcoming. The proposed RF model showed an excellent prediction accuracy when it was first validated in predicting the effluent conductivity for both CDI (R2 = 0.86) and BDI (R2 = 0.95) data. Moreover, the RF model successfully predicted the concentration of each ion (Na⁺, K⁺, Ca2⁺, and Cl⁻) from the conductivity values. The accuracy of the ion concentration prediction was even higher than that of the effluent conductivity prediction, likely owing to the linear correlation between the input and output variables of the dataset. The effect of the sampling interval was also evaluated for conductivity and ion concentrations, and there was no significant difference up to a sampling interval of <80 s based on the error value of the model. These findings suggest that an RF model can be used to predict ion concentrations in CDI/BDI, which may be used as core indicators in evaluating desalination performance.

Charge exchange recombination spectroscopy on the alkali beam of Wendelstein 7-X.

Measurements of ion temperature profiles are required to assess the energy and particle transport processes in the Wendelstein 7-X stellarator. This device is equipped with a diagnostic alkali beam, which can be utilized to determine local impurity temperatures and densities by Charge Exchange Recombination Spectroscopy (CXRS). It could provide such profiles in the edge plasma, where other diagnostics are less efficient. With this contribution, first results of CXRS measurements on the sodium beam from the scientific operation phase OP2.1 are presented. The spectroscopic system was in commissioning phase lacking some of the final optical components. Thus, the aim of the diagnostics during this campaign was to explore the measurement capabilities. Based on the processed spectra, the prospects of C5+ and C6+ ion temperature and concentration measurements are discussed. The results indicate that with the final optical setup under installation, the diagnostics could provide ion temperature profiles in the edge with 3mm radial resolution and at least 1s temporal resolution.

Study of corrosion resistance of superhydrophobic hydrotalcite cement mortar in chlorine salt environment

Reinforced concrete structures are susceptible to reduced service life owing to the erosion caused by the of chlorine-containing, external environment and internal chloride. In this paper, a superhydrophobic hydrotalcite cement mortar was studied with internal and external cooperation against chloride ion erosion. The effect of different hydrotalcite substitution amounts on the chlorine corrosion resistance of the mortar was investigated. The mortar exhibited good resistance to chlorine corrosion, and the corrosion resistance rate increased by 91.83 %. The free chloride ion concentration measurement and rapid chloride migration test exhibited that the prepared mortar effectively resisted chloride ion invasion and reduced the content of free chloride ions in the mortar. The proposed anticorrosion method is expected to have potential application prospects for concrete structures under chloride salt environments.

Investigating the Urinary Salt Losing Phenotype in R607H and L919X Mutant Mice with Distal Renal Tubular Acidosis

Introduction: The renal collecting duct consists of two cell types: principal and intercalated cells (ICs, alpha- and beta-type). These cells play a crucial role in regulating fluid, electrolyte, and acid-base homeostasis. Specifically, alpha-ICs promote secretion of protons into the urine through an apical proton ATPase while enabling the reabsorption of bicarbonate into the blood via the basolateral protein, kidney anion exchanger 1 (kAE1). Genetic mutations that impact IC cell function can lead to a condition called distal renal tubular acidosis (dRTA). Patients with dRTA typically exhibit alkaline urine, metabolic acidosis, electrolyte imbalances, and urinary ion loss. Study Objective and Hypothesis: Some dRTA patients continue to exhibit impaired conservation of sodium, despite sustained correction of their acidosis. The mechanisms that lead to this impairment need further investigation. Our lab has two dRTA kAE1 knock in (KI) mouse models, L919X (LX) and R607H (RH), that recapitulate classical metabolic acidosis seen in human patients. We hypothesize that these mice serve as an effective model for studying the cause behind the persistent urinary ion loss. The objectives of our work are to 1) determine whether our mouse models accurately reflect the urinary ion loss seen in dRTA patients, 2) comprehensively characterise the previously unpublished mouse line, kAE1 KI L919X, and 3) elucidate the mechanism behind this urinary salt loss. Methods: To test our hypothesis, we fed wild-type (WT) and dRTA mutant mice a low NaCl, acid, or combination (NaCl + acid) diet, to mirror conditions previously studied in human patients. We collected urine and plasma from the mice to measure ion concentrations and pH. We harvested and processed their kidney and gut tissues for analysis through qRT-PCR, immunoblot, and immunofluorescence to investigate acid-base and salt transports in the collecting duct and thick ascending limb. We aimed to identify potential alterations in these transporters between WT and KI mice. Results: On the low NaCl diet, there were little differences between WT and KI mice, either in comparison to each other or relative to their baseline conditions. However, the combination diet revealed a urinary salt losing phenotype in the RH and LX KI mice. These KI mice also displayed hypernatremia, hyperchloremia, and a failure to secrete potassium and to properly concentrate their urine. qRT-PCR analysis of whole kidney tissues revealed a surprising increase in the paracellular transport pathways, including claudin-4 and claudin-10b in the KI compared to WT. Initial immunoblots indicate a concordant upregulation and downregulation of protein expression that aligns with transcriptional changes seen at the mRNA level. Conclusion: Our current findings suggest a defective collecting duct function in the KI mice, thus validating our hypothesis. Additionally, there appears to be a compensatory mechanism at play in earlier nephron segments to rescue ion homeostasis. The results from this research may contribute to improved treatment options for patients that suffer with this severe disease. It will also deepen the understanding of the interconnected and complex functions of the nephron, aiding in treatment of other major conditions like hypertension or end-stage renal disease. Canadian Institutes of Health Research (CIHR), Canada Graduate Scholarship - Master's CIHR, and Kidney Foundation of Canada. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Colorimetric detection of electrolyte ions in blood based on biphasic microdroplet extraction

BackgroundTimely diagnosis and prevention of diseases require rapid and sensitive detection of biomarkers from blood samples without external interference. Abnormal electrolyte ion levels in the blood are closely linked to various physiological disorders, including hypertension. Therefore, accurate, interference-free, and precise measurement of electrolyte ion concentrations in the blood is particularly important. ResultsIn this work, a colorimetric sensor based on a biphasic microdroplet extraction is proposed for the detection of electrolyte ions in the blood. This sensor employs mini-pillar arrays to facilitate contact between adjacent blood microdroplets and organic microdroplets serving as sensing phases, with any color changes being monitored through a smartphone's colorimetric software. The sensor is highly resistant to interference and does not require pre-treatment of the blood samples. Remarkably, the sensor exhibits exceptional reliability and stability, allowing for rapid enrichment and detection of K+, Na+, and Cl− in the blood within 10 s (Cl−), 15 s (K+) and 40 s (Na+) respectively. SignificanceThe colorimetric sensor based on biphasic microdroplet extraction offers portability due to its compact size and ease of operation without the need for large instruments. Additionally, it is location-independent, making it a promising tool for real-time biomarker detection in body fluids such as blood.

Effect of chloride binding and sulfate ion attack on the chloride diffusion in calcium sulfoaluminate-based material under seawater environment

The diffusion of chloride ions in reinforced concrete under the seawater environment will affect the physical or mechanical properties and durability. Sulfate ions also influence the diffusion of chloride ions by generating expansion products through physical and chemical reactions. Further research on the effects of chloride binding and sulfate ion attack on chloride ion diffusion will deepen the understanding of concrete failure mechanism. In this paper, a quaternary blend based on calcium sulfoaluminate (CSA) cement was prepared and laboratory immersion tests were conducted in artificial seawater with varying salt concentrations. Initially, chloride ion concentration measurements and XRD tests were conducted at different corrosion ages and salt concentrations. Subsequently, the chloride binding properties of CSA-based materials was quantified through the analysis of chloride ion concentration and the phases of hydration products. Meanwhile, the corrosive effect of sulfate ions on chloride ion diffusion was determined corresponds to the content of expansive hydration products. Furthermore, numerical simulations were employed to evaluate the impact of sulfate ion corrosion, chloride binding, and their combined effects on chloride ion diffusion, and the results were compared with free chloride ion concentration (Cf). The results indicate that the total chloride ion concentration (Ct) exhibits a linear relationship with increasing salt concentrations of seawater in CSA-based materials. Meanwhile, the bound chloride ion concentration (Cb) follows a logarithmic growth pattern. The chloride binding rate experiences a linear decline with the increase of chloride ion concentration in the artificial seawater. Additionally, the relationship between Cf and Cb or Ct can be described using different isothermal adsorption models for the CSA-based materials. Among these models, the Langmuir model is suitable for characterizing the relationship between Cf and Cb, while the Freundlich model is suitable for describing the relationship between Cf and Ct. Furthermore, it is noteworthy that sulfate ion attack and chloride binding exert nearly equivalent effects on the diffusion of chloride ions in CSA-based materials at short corrosion age and low chloride ion concentration. However, the corrosive impact of sulfate ions gradually evolves into the dominant factor in the progression of corrosion over time and the increase in seawater salt concentration.

Natural Moroccan bentonite clay as an adsorbent for nutrient removal from synthetic leachate: Performance and evaluation

To ensure the protection of public health and environmental integrity, while also meeting effluent regulation standards, it is critical to treat leachate due to its composition of hazardous substances before it is introduced into the environment. Pollution from leachate is characterized by several indicators, including COD, BOD5, conductivity, pH, and the presence of various ions such as ammonium, nitrite, nitrate, chloride, and orthophosphate. This research examines the adsorption properties of natural bentonite clay from Nador, located in eastern Morocco, for its efficacy in removing ammonium, nitrate, and nitrite ions from synthetic leachates. We present the outcomes of adsorption experiments utilizing bentonite clay to eradicate these nitrogen-based ions from artificial leachate, using UV adsorption spectroscopy for the measurement of ion concentrations before and after adsorption. Additionally, the study evaluates the efficiency of bentonite clay in adsorption, identifying the optimal amount of clay required for effective pollutant reduction. Our results demonstrate that, following a 24-hour mixing period, the adsorption rates for ammonium, nitrate, and nitrite ions were roughly 48%, 40%, and 85% at 35 °C, and 40%, 15%, and 25% at 25 °C, respectively. These findings suggest that modulation of agitation duration and temperature can significantly improve adsorption efficiency, with elevated temperatures facilitating shorter reaction times and higher adsorption rates for nitrogen ions. Ultimately, the research confirms the potential of bentonite clay as an effective medium for the removal of these contaminants from landfill leachate, offering a promising approach for enhancing environmental sustainability.

Algal growth inhibition test with TEMPO-oxidized cellulose nanofibers

Ecotoxicity data on cellulose nanofibers (CNFs) are limited despite their wide potential applications prospects, such as structural and packaging materials, filters, coatings, foods, and cosmetics. In this study, toxicity tests of 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-oxidized CNFs (TEMPO-CNFs), which are one of the major CNF products commercially available in Japan, on the green alga Raphidocelis subcapitata were conducted. As nanomaterials are considered difficult-to-test substances, the Organisation for Economic Co-operation and Development has released a guidance document that provides considerations regarding ecotoxicity tests of nanomaterials. In the algal growth inhibition tests of TEMPO-CNFs, there were specific issues to be examined, including the effects of medium components on the characteristics of TEMPO-CNFs, CNF interference with algal density measurements, algal interference with CNF measurements, and the effects of ion concentration changes in the test medium by the addition of CNFs on algal growth. To examine these issues, we conducted preliminary studies and established a suitable test method for algal growth inhibition tests of TEMPO-CNFs. We confirmed that the components in the medium for algal growth inhibition tests had negligible effects on the characteristics (zeta-potential, viscosity, and morphology) and concentration stability of TEMPO-CNFs and that in vitro and in vivo fluorescence measurements were applicable for estimating the algal densities, without interference by TEMPO-CNFs. In contrast, we observed that the grown algae interfered with the CNF concentration measurements. Therefore, we established a method to correct the measured CNF concentrations by estimating the algal contribution. Furthermore, we found that the nutrient salt concentrations in the medium changed due to interactions with CNFs; however, this change did not affect algal growth. Based on the results of the preliminary studies, algal growth inhibition tests of TEMPO-CNFs were conducted using in vitro and in vivo fluorescence measurements, along with measurements of CNFs and ion concentrations in the test dispersions. The test results showed that no growth inhibition was observed on growth rate or yield even at the maximum CNF concentration of 100 mg/L, suggesting that the ecological effect of TEMPO-CNFs on algae was relatively low. The results of this study will be valuable for conducting ecotoxicity assessments on additional CNFs and comparable nanomaterials in future studies.

Measurement of sulfate ion concentration in segregated post-tension grout

Corrosion of steel strand embedded in deficient grout has been associated with elevated concentrations of sulfate ions stemming from grout segregation and the adverse influences of excess mix water and grout prehydration. There have been discussions about appropriate ways to assess sulfate ion levels in the grout pore water. Various test methodologies can include varying material conditioning procedures, including heating, drying, and chemical reactions that can influence the level of sulfate ion aggregation in the test leachate from the initial bleed water from the bulk material. In this study, the sulfate content was measured by leaching and alternative methods such as XRF and bleed water testing. Six leaching methods were employed to assess the effect of leaching heating, heating time, leaching volume, grout sample mass, and drying temperature. Leaching of larger grout sample mass can yield higher leachate sulfate concentrations, but the concentrations were not commensurate with the larger grout mass. Leaching of a larger grout sample mass with a mass-to-water ratio of 1:10 was not shown to be efficient in the dissolution of sulfate ions. Larger mass-to-water ratio (1:40) yielded higher sulfate concentrations in the leachate and normalized grout mass. Pre-drying of grout samples to 100 °C for 24 h was shown to incur losses in sulfate content. Recommendations of test methods to assess the sulfate ion content from segregated and hardened grout were made.

How to Rapidly Evaluate Uranium Adsorption Capacity Using Only a Portable Geiger Counter?

AbstractThe development of the nuclear industry has stimulated research in uranium extraction from seawater (UES) by adsorption. However, in practical applications, it's hard to equip various ion concentration measurement instruments for real‐time characterizing uranium adsorption capacity. Given the radioactive property of uranium, if only a Geiger counter is possessed, how it can be utilized to rapidly evaluate uranium adsorption in the adsorbent? This study proposes the Geiger‐Uranium‐Distance model, which establishes correlations among Geiger counter readings, uranium adsorption capacity, and distance, thereby offering a viable approach. While maintaining a constant radius for the adsorbent stack point, during the laboratory phase, the average molecular mass (MA) and the kGg(z) values of the original adsorbent are determined. In practical applications, the surrounding radiation background GE (µSv h−1) is detected. Subsequently, the Geiger counter is vertically positioned above the stacked point of adsorbent after uranium adsorption. Utilizing the measured radiation intensity value G (µSv h−1), and employing the equation , the uranium adsorption capacity Qe can be obtained.

The pH estimation of decoction of hingu (Ferula foetida Regel,), chitraka (Plumbago zeylanica Linn), dhataki (Woodfordia fruticosa kurz), shatavari (Asperagus racemosus willd), shunthi (Zingiber officinale Rosc), maricha (Piper nigrum Linn), gokshura (Tri

The pH is measured on a scale of 0-14 with lower values indicating high H+ which is more acidic and higher values indicating H+ ion activity which is less acidic. The pH of 7 is considered as neutral. The acids are the substances that produce free hydrogen ions(H+) when dissolved in water. Bases are substances that produce hydroxyl ions(OH-) when dissolved in water. Acidic solutions are rich in hydrogen ions and basic solutions are poor in hydrogen ions. Some acids dissociate only partly, releasing large amounts of H+ ions, and are called as strong acids. In same way, bases that dissociate partly are called weak bases and those that dissociate completely are called as bases. The acidic or basic property of substances is measured in terms of pH. It is a measurement of the hydrogen ion concentration. pH is defined as the negative logarithm(Base 10) of hydrogen ion concentration. pH= - log[H+] If the hydrogen ion concentration id very high, the pH value is very low. This is determined using a scale ranging from 0-14 called the pH scale. It was introduced by a Danish chemist Soren Peder Lauritz Sorensen. Substances with pH lower than 7 are acidic, those with pH equal to 7 are neutral and those with pH greater than 7 are basic in nature. The pH of water is 7. In the present work the decoction of Hingu(Ferula foetida Regel,), Chitraka(Plumbago zeylanica Linn), Dhataki(Woodfordia fruticosa kurz), Shatavari(Asperagus racemosus willd), Shunthi(Zingiber officinale Rosc), Maricha(Piper nigrum Linn), Gokshura(Tribulus terrestris Linn) and Chandana(Santalum album Linn) were subjected for experimentation. The observed values were tabulated. The pH estimation helps to determine the acidic and basic strength of acids and bases.

Assessing brain integrity in patients with long-term and well-functioning metal-based hip implants.

Production of metal debris from implant wear and corrosion processes is now a well understood occurrence following hip arthroplasty. Evidence has shown that metal ions can enter the bloodstream and travel to distant organs including the brain, and in extreme cases, can induce sensorial and neurological diseases. Our objective was tosimultaneously analyze brain anatomy and physiology in patients with long-term and well-functioning implants. Included were subjects who had received total hip or hip resurfacing arthroplastywith an implantation time of a minimum of 7 years (n = 28) and age- and sex-matched controls (n = 32). Blood samples were obtained to measure ion concentrations of cobalt and chromium, and the Montreal Cognitive Assessment was performed. 3T MRI brain scans were completed with an MPRAGE sequence for ROI segmentation and multiecho gradient echo sequences to generate QSM and R2* maps. Mean QSM and R2* values were recorded for five deep brain and four middle and cortical brain structures on both hemispheres: pallidum, putamen, caudate, amygdala, hippocampus, anterior cingulate, inferior temporal, and cerebellum. No differences in QSM or R2* or cognition scores were found between both groups (p > 0.6654). No correlation was found between susceptibility and blood ion levels for cobalt or chromium in any region of the brain. No correlation was found between blood ion levels and cognition scores.Clinical significance: Results suggest that metal ions released by long-term and well-functioning implants do not affect brain integrity.

Acidification is required for calcium and magnesium concentration measurements in equine urine

BackgroundAcidification of equine urine to promote dissociation of ion complexes is a common practice for urine ion concentration measurements. The objective of this study was to evaluate the effect of acidification and storage after acidification on calcium (Ca), magnesium (Mg) and phosphate (P) concentrations and on fractional excretion (FE) of these electrolytes. Thirty-two fresh equine urine samples were analysed between December 2016 and July 2020. Complete urinalysis (stick and sediment) was performed on all samples. Ca, Mg, P and creatinine concentrations were measured in supernatant of centrifuged native urine, urine directly centrifuged after acidification and urine centrifuged 1 hour after acidification. Urine was acidified with hydrochloric acid to reach a pH of 1–2. Ca, Mg, P and creatinine concentrations were also measured in blood plasma, and fractional excretion of each electrolyte was calculated. Equality of medians was tested with Friedman tests and Bland-Altman bias plots were used to show the agreement between conditions.ResultsAcidification had a statistically significant effect on Ca and Mg concentrations, FECa and FEMg. Bland-Altman plot revealed a strong positive proportional bias between Ca concentration in native and acidified urine with a mean bias of 17.6 mmol/l. For Mg concentration, the difference between native and acidified urine was small with a mean bias of 1.8 mmol/l. The increase in FECa was clinically relevant. Storage of acidified urine had no effect on any of the measured ion concentrations. All P concentrations in native urine samples were below the detection limit of the assay and statistical analysis and calculation of FEP was not possible.ConclusionsUrine acidification is essential for accurate measurement of Ca and Mg concentrations and therefore FE calculations in equine urine. Storage time of 1 hour after acidification does not significantly change Ca and Mg concentrations.

The Effect of Type and Concentration of Receiving Phase on Silver Separation Efficiency by Supported Liquid Membrane Technique

The Effect of The Type and Concentration of The Receiving Phase on The Efficiency Of Silver Separation with Liquid Supported Membrane Techniques. The process of making negative x-ray films in a radiology laboratory produces liquid wastes containing various chemical compounds with the main content being Ag metal (in the form of Ag+ cations). This waste is categorized as a dangerous and toxic material. Therefore it is necessary to separate the Ag metal before it is discharged into the environment so as not to be harmful to life and the environment. One of the separation techniques that can be used is with supported fluid membrane technique (Supported Liquid Membrane, SLM). The supported liquid membrane has three important components: the feed phase containing the component to be separated, the membrane phase containing the carrier compound and the receiving phase containing the integral component. The three-phase composition determines the efficiency of the separation process. This study aims to identify the type and concentration of the receiving phase solution to improve silice metal separation efficiency by SLM technique. To obtain an efficient composition in the recipient phase was carried out by varying the type of acid received solution ie H3PO4, HNO3 and CH3COOH with respective concentrations of 0.01; 0.05; 0.10; 0.15; and 0.20 M. Measurement of metal ion concentration of Ag+ before and after transport was determined by Atomic Absorption Spectrophotometer (SSA) at wavelength 328,22 nm. Based on the result of research that type and concentration of acid solution in the receiving phase has an effected on separation efficiency. The optimum transport percentage has obtained on the used of H3PO4 receptor solution at a concentration of 0.1 M with a percentage of Transport Ag of 46.84%.

DriveLEDs: software for synchronous control and video acquisition of fluorescent signals

Current research uses various fluorescent biosensors to measure ion concentrations, neuronal activity, or cellular components in biological preparations. Several free solutions are available to researchers for recording or analysing fluorescent signals. However, when using different software packages, there are great difficulties in converting data between them. Problems also arise with linking and coordination of individual hardware devices into a single measurement system. Our paper presents useful software that allows to avoid most of these problems. It enables the recording, online visualization and preliminary analysis of fluorescent signals in brain cells and other experimental models. We describe and test software optimized for ratiometric measurements. The program selects device operating modes that allow reliable changes in illumination wavelength, camera image capture, and online graphical visualization of fluorescent signal amplitudes or ratiometric data. The performance of the software was successfully tested on mouse brain using two experimental models; i) simultaneous monitoring of intracellular chloride and hydrogen in transgenic mice expressing genetically encoded biosensor; ii) recording changes in reactive oxygen species during synaptic stimulation of neurons in mouse hippocampal slices. This software allows to overcome the incompatibility of the devices used and reduce the cost of experimental measurements. The software is completely original, easy to use and may be of interest to many scientists involved in the analysis of light-controlled signals in a variety of experimental models, including drug screening, epilepsy models, and other applications. The software is open-source product and can be obtained via GitHub: https://github.com/AndreyZakharovExp/DriveLEDs.

A Floating Capsule Electrochemical System for In Situ and Multichannel Ion-Selective Sensing.

Free-floating electrochemical sensors are promising for in situ bioprocess monitoring with the advantages of movability, a lowered risk of contamination, and a simplified structure of the bioreactor. Although floating sensors were developed for the measurement of physical and chemical indicators such as temperature, velocity of flow, pH, and dissolved oxygen, it is the lack of available electrochemical sensors for the determination of the inorganic ions in bioreactors that has a significant influence on cell culture. In this study, a capsule-shaped electrochemical system (iCapsuleEC) is developed to monitor ions including K+, NH4+, Na+, Ca2+, and Mg2+ based on solid-contact ion-selective electrodes (SC-ISEs). It consists of a disposable electrochemical sensor and signal-processing device with features including multichannel measurement, self-calibration, and wireless data transmission. The capacities of the iCapsuleEC were demonstrated not only for in situ measurement of ion concentrations but also for the optimization of the sensing electrodes. We also explored the possibility of the system for use in detection in simulated cell culture media.

IoT-interfaced solid-contact ion-selective electrodes for cyber-monitoring of element- specific nutrient information in hydroponics

This study aims to monitor element-specific nutrient information during hydroponic cultivation by IoT-interfaced miniaturized ion sensors. Because of size, cost, and manufacturing advantages, solid-contact ion-selective electrodes (SCISEs) were fabricated as an ion sensor array and interfaced with wireless embedded-systems to construct an IoT nutrient sensor system (IoNSS) for the first time. The entire IoNSS framework was composed of (i) a nutrient solution sampling and sensing module with SCISEs controlled by an Arduino Due® microcontroller, (ii) a Wio Terminal® microcontroller for automated procedure setting, data recording, and wireless transmission, (iii) a private cloud server (a Network Attached Storage equipped with Node-RED® and MongoDB®) for data management, and (iv) MQTT webpage-based interactive interfaces. In experiments, we found that potentiometric signal resolution and noise of the Arduino-interfaced SCISEs were significantly improved and approached to instrumental DAQ-like quality by additional delta-sigma ADC (ADS1115®) chip conditioning. This facilitated cost-effective harvest of precise and high-quality IoT ion sensor data. Before on-site applications, each SCISE was two-point calibrated in multiple-ion solutions and was checked with the fixed interference method. The ion concentration measurements were also compared with those of commercial ISEs and ion chromatography. To test the system’s feasibility, the IoNSS was applied to cyber-monitoring of K+, NO3–, and NH4+ concentrations during two-week hydroponic cultivation of arugula (E. vesicaria) in an indoor plant factory (in Northern Taiwan) with a modified Cornell solution and an outdoor greenhouse (in Southern Taiwan) with a modified Yamasaki solution, respectively. It was demonstrated that the IoNSS was capable of real-time observation of the crop’s nitrate/ammonium utilization and nutrient solution’s EC-element dependency. Besides, the web interfaces successfully reported growing condition-dependent ion signals in a simultaneous and remote manner. To sum up, this work achieves novel cybermonitoring of element-specific nutrients by IoT-interfaced SCISEs and paves a promising way for intelligent hydroponic management.

Accelerated Bone Regeneration on the Metal Surface through Controllable Surface Potential.

Surface potential is rarely investigated as an independent factor in influencing tissue regeneration on the metal surface. In this work, the surface potential on the titanium (Ti) surface was designed to be tailored and adjusted independently, which arises from the ferroelectricity and piezoelectricity of poled poly(vinylidene fluoride-trifluoroethylene) (PVTF). Notably, it is found that such controllable surface potential on the metal surface significantly promotes osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) in vitro as well as bone regeneration in vivo. In addition, the intracellular calcium ion (Ca2+) concentration measurement further proves that such controllable surface potential on the metal surface could activate the transmembrane calcium channels and allow the influx of extracellular Ca2+ into the cytoplasm. That might be the reason for improved osteogenic differentiation of BMSCs and bone regeneration. These findings reveal the potential of the metal surface with improved bioactivity for stimulation of osteogenesis and show great prospects for fabricable implantable medical devices with adjustable surface potential.

Remote Measurements of Tear Electrolyte Concentrations on Both Sides of an Inserted Contact Lens.

In this paper, a method is described to perform ion concentration measurements on both sides of an inserted contact lens, without physical contact with the eye or the contact lens. The outer surface of an eye is covered with a tear film that has multiple layers. The central aqueous layer contains electrolytes and proteins. When a contact lens is inserted, it becomes localized in the central layer, which creates two layers known as the pre-lens tear film (PLTF) and the post-lens tear film (PoLTF). The PoLTF is in direct contact with the sensitive corneal epithelial cells which control electrolyte concentrations in tears. It is difficult to measure the overall electrolyte concentration in tears because of the small 7 μL volume of bulk tears. No methods are known, and no method has been proposed, to selectively measure the concentrations of electrolytes in the smaller volumes of the PLTF and the PoLTF. In this paper, we demonstrate the ability to localize fluorophores on each side of a contact lens without probe mixing or diffusion across the lens. We measured the concentration of sodium in the region of the PoLTF using a sodium-sensitive fluorophore positioned on the inner surface of a contact lens. The fluorescence measurements do not require physical contact and are mostly independent of eye motion and fluorophore concentration. The method is generic and can be combined with ion-sensitive fluorophores for the other electrolytes in tears. Instrumentation for non-contact measurements is likely to be inexpensive with modern opto-electronic devices. We expect these lenses to be used for measurements of other ions in the PLTF and the PoLTF, and thus become useful for both research and in the diagnosis of infections, keratitis and biomarkers for diseases.