pH Sensor Research Articles

Design and Development of Automated Nutrient Regulation System for Hydroponics Unit

Hydroponics is a method of growing plants without soil. Hydroponics, a subset of hydro culture, is a growing plant without soil, using mineral nutrient solutions in a water solvent. In soil less culture especially, hydroponics, the problem of regular maintenance of nutrient solution and required technical knowledge. The automation in hydroponics further helps to boom up the hydroponic cultivation. Automated nutrient regulation in hydroponics environment with automatic nutrient feed technology was developed and tested in the present study. The experiment was carried out an automated controlling and regulation of pH, TDS, temperature in polyhouse hydroponic system using Arduino-Uno controller, solenoid valves containing nutrients, water, pH-up, and pH-down and sensors. In this study, the sensors are connected to Arduino-Uno controller in which liquid crystal display (LCD) of Arduino-Uno circuit controls and regulates the system based on the coding which has been programmed previously. Calibration was done for all the parameters in the automated system. TDS and pH values of nutrient solution were recorded by using TDS and pH sensor probes respectively were fed to Arduino which adjusts the values, if required, through actuators. The prototype model was able to monitor and control the pH and TDS of hydroponic water in the required range with high accuracy.

E-SDAPONIKS: A Cloud-Based Aquaponics Management System with Data Analytics

This study endeavors to create an advanced aquaponics management system, elevating monitoring capabilities through the integration of environmental sensors. By harnessing the power of the Internet of Things (IoT) and cloud-based technology, users gain unprecedented control over devices while seamlessly recording and analyzing system data. Complementing this, a user-friendly mobile application provides realtime insights into feed consumption, water parameters, and harvest schedules, enhancing operational efficiency. The Agile Methodology serves as the framework for this project, enabling a flexible and iterative approach to hardware and software development. Key hardware components include temperature and humidity sensors, electrical conductivity sensors, and pH sensors, essential for comprehensive monitoring. Facilitating seamless integration, an ESP32 microcontroller manages these sensors, boasting built-in Bluetooth and Wi-Fi modules to facilitate connectivity with the mobile application. In assessing project performance, adherence to ISO 25010 requirements and IEEE standards validates the system’s robustness and reliability.

A multiplexed sensing system with multimodal readout electronics and thread-based electrochemical sensors for high throughput screening

High throughput screening (HTS) based on microwell (or bioreactor) arrays is a well-established approach for rapid screening and identification of lead molecules or target analytes for drug discovery and other applications in biotechnology. However, it has been challenging to scale up these platforms due to the lack of integrated sensors to monitor the microenvironment of each microwell in the array needed. In this work, we present a practical solution for a miniaturized multiplexed sensing system with integrated circuitry capable of performing continuous electrochemical potentiometric and amperometric measurements. The platform uses lightweight multiplexed electrochemical sensors implemented on thin textile threads, all of which share a single operational amplifier (op-amp) and a switch network for both voltage and current measurements. The resulting platform forgoes the need for large-area sensors or bulky multichannel potentiostat with a simple readout circuitry capable of multimodal measurements. The design and validation of the multiplexed sensing system have been reported in the context of measuring pH and oxygen (O2), which are crucial biomarkers for any HTS application. The thread-based pH and O2 sensors possess sensitivities of ∼65.87 mV/pH for the pH sensor (n = 3) and 0.6621 nA/mg L-1 for the O2 sensor (n = 3). This architecture is modular such that it can be easily extended to monitoring multiple biomarkers employing thread-based sensors and sharing the same readout circuitry, making it a practical and versatile tool for biotechnology research.

Application of 3D and 4D Printing in Electronics

Nowadays, additive manufacturing technologies have impacted different engineering sectors. Three- and four-dimensional printing techniques are increasingly used in soft and flexible electronics thanks to the possibility of working contemporarily with several materials on various substrates. The materials portfolio is wide, as well as printing processes. Shape memory polymers, together with composites, have gained great success in the electronic field and are becoming increasingly popular for fabricating pH, temperature, humidity, and stress sensors that are integrated into wearable, stretchable, and flexible devices, as well as for the fabrication of communication devices, such as antennas. Here, we report an overview of the state of the art about the application of 4D printing technologies and smart materials in electronics.

Triple-function carbon-based Ca2+ ion-selective pH ring microelectrode to study real-time bacteria-mediated hydroxyapatite corrosion

BackgroundThe local pH change mediated by the pathogenic bacterial species Streptococcus mutans plays a significant role in the corrosion of hydroxyapatite (HA) present in the tooth in the dynamic oral cavity. The acid produced by the bacteria decreases the local pH and releases Ca2+ ions from the HA. We studied the bacteria-mediated demineralization of HA by scanning electrochemical microscopy (SECM) after growing S. mutans biofilm on HA for 7 days. ResultsWe notably developed a triple-function SECM-compatible tip that could be positioned above the biofilm. It can also measure the pH and [Ca2+] change simultaneously above the biofilm-HA substrate. The triple-function SECM tip is a combination of a potentiometric pH sensor deposited with iridium oxide and a dual-function carbon-based Ca2+ ion-selective membrane electrode with a slope of 67 mV/pH and 34.3 mV/log [Ca2+], respectively. The distance-controlled triple-function SECM tip monitored real-time pH and [Ca2+] changes 30 μm above the S. mutans biofilm. The high temporal resolution pH data demonstrated that after approximately 20 min of sucrose addition, S. mutans started to produce acid to titrate the solution buffer, causing a pH change from 7.2 to 6.5 for HA and from 7.2 to 5 for the glass substrate. We observed that, after 30 min of acid production, ∼300 μM of Ca2+ ions were increased at pH 6.5 above the biofilm surface as a result of the pH change in the local microenvironment. After the release of Ca2+ from HA, the pH environment again shifted toward the neutral side, from 6.5 to 7.2. Therefore, precipitation of Ca2+ happens at the top of the biofilm, thus corroding the HA from underneath. For a glass substrate, in contrast, no Ca2+ ions were released, and the pH did not change back to 7.2. We were able to observe the dynamics of the HA demineralization–remineralization process simultaneously with our newly developed triple-function SECM tip or microprobe. SignificanceThis technique could notably advance the study of similar complex processes, such as bacteria-mediated corrosion in biomedical and environmental contexts.

IMSIS: An instrumented microphysiological system with integrated sensors for monitoring cellular metabolic activities

Well plates are widely used in biological experiments, particularly in pharmaceutical sciences and cell biology. Its popularity stems from its versatility to support a variety of fluorescent markers for high throughput monitoring of cellular activities. However, using fluorescent markers in traditional well plates has its own challenges, namely, they can be potentially toxic to cells, and thus, may perturb their biological functions; and it is difficult to monitor multiple analytes concurrently and in real-time inside each well. This paper presents a fully instrumented microphysiological system with integrated sensors (IMSIS) with a similar well format. Each well in the microphysiological system has a set of sensors for monitoring multiple metabolic analytes in real-time. The IMSIS platform is supported by integrated bioelectronic circuits and a graphical user interface for easy user configuration and monitoring. The system has integrated microfluidics to maintain its microphysiological environment within each well. The IMSIS platform currently incorporates O2, H2O2, and pH sensors inside each well, allowing up to six wells to perform concurrent measurements in real-time. Furthermore, the architecture is scalable to achieve an even higher level of throughput. The miniaturized design ensures portability, suitable for small offices and field applications.The IMSIS platform was successfully used to monitor in real-time the mitochondrial functions of live bovine embryos in O2 consumption, H2O2 release as an indication of ROS production, and extracellular acidity changes before and after the introduction of external substrates.

PENGEMBANGAN PERANGKAT MULTI SENSOR UNTUK PRECISION FARMING MONITORING MEDIA TANAM

The development of a multi-sensor device and the implementation of a data transmission system to a database for predicting plant suitability parameters are the focus of this paper. This technology enables accurate and continuous data collection for agricultural condition monitoring. The study utilizes a DHT22 sensor for air temperature and humidity, a pH sensor for soil pH, a soil moisture sensor for soil moisture, a rain gauge sensor for rainfall, and a raindrop sensor for rain detection. The data from these sensors are managed by an ESP32 microcontroller and transmitted to a Firebase database. The multi-sensor device was functionally tested and compared with valid reference sensor readings. The results show that all the multi-sensor devices and the recording system in the Firebase database functioned well. The average measurement error for the DHT22 temperature sensor was 1.15°C, with 2.9% for humidity, 0.72% for the pH sensor, and the soil moisture sensor showed 100% accuracy. This system can be applied as a parameter for predicting the suitability of plant types with soil and environmental conditions.

Hydrothermally synthesized Al-doped β-Ga2O3 microrods for enhanced pH sensing performance

In our study, Al-doped β-Ga2O3 microrods were deposited on FTO glass substrate via hydrothermal method followed by calcination at 700 °C for 3 h. The Al-doped β-Ga2O3 microrods were characterized using XRD, SEM, XPS, and FTIR spectroscopy techniques. The intrinsic β-Ga2O3 extended-gate field-effect transistor (EGFET)-based pH sensor exhibited a pH sensitivity of 57.29 mV/pH with 99.34 % linearity within the pH range of 3–11. Conversely, the Al-doped β-Ga2O3 EGFET-pH sensor, containing 0.52 at. % of Al, demonstrated an elevated pH sensitivity of 77.63 mV/pH with 99.17 % linearity. Our findings indicate that the incorporation of Al enhances the pH sensing capabilities of β-Ga2O3 microrods to the presence of additional binding sites facilitated by its improved specific surface area. Remarkably, even a minute amount (0.52 at. %) of Al doping in β-Ga2O3 suffices to significantly improve the performance of pH sensing. These results underscore the potential of Al-doped β-Ga2O3 as a promising material for development of high-performance ion or biosensors.

Systematic evaluations and integration of Assam indigenous Joha rice starch in intelligent packaging films for monitoring food freshness using beetroot extract

It is becoming increasingly important to have starch sources with different physicochemical properties to meet the needs of new applications in food, packaging, bioplastic, and pharmaceutical industries. The first part of this study dealt with the isolation of starch from culturally, geographically, nutritionally esteemed, and high-yielding Assam Joha rice. Fine and uniform particle size (6.3 ± 0.09 μm), high amylose content (28 ± 1.03 %), swelling behavior, viscoelastic rheological behavior, moderate gelatinization temperature (66 ± 1.7 °C), thermostable nature, type A crystallographic pattern with high (45 ± 3.3 %) crystallinity, and suitable microbial quality make the Joha rice derived starch physico-chemically and functionally suitable for potential applications in diverse domains. The latter part of the study focuses on one of the applications of derived starch as a suitable matrix for intelligent packaging films with the incorporation of betanin-enriched beetroot extract (BRE) as a bio-based pH sensor. The addition of 1.0 % w/v BRE to the starch film (starch-BRE III) significantly increased its functionality by reducing UV–visible light transmittance and water vapor permeability, along with enhancing flexibility and hydrophobicity due to intermolecular bonding between BRE and the starch film matrix. Moreover, starch-BRE films with different BRE concentrations were successfully used to monitor the real-time freshness of white meat (chicken and fish) and Indian cottage cheese samples. Overall, the results indicated that starch-BRE III has great potential as an intelligent packaging material for monitoring food freshness.

Smart wireless flexible bandage containing drug loaded polycaprolactone microparticles for real-time monitoring and treatment of chronic wounds.

The quality of life is negatively impacted by chronic wounds for more than 25 million people in the US. They are quite prone to infection, which may lead to the eventual loss of a limb. By exposing the ulcers to treatment agents at the appropriate time, the healing rate is increased. On-demand drug release in a closed-loop system will aid us in reaching our goal. In this study, we have developed a platform capable of real-time diagnosis of bacterial infection by wirelessly reading wound pH, as well as slow and on-demand local administration of antibiotics. The drug carrier microparticles, an electrical patch, a thermoresponsive hydrogel with an integrated microheater, and a flexible pH sensor comprised the closed-loop patch. Here it is reported that slow and smart release of cefazolin can be addressed by incorporation of drug encapsulated hydrophobic microparticles embedded into a thermo-responsive hydrogel. The utilization of a programmable bandage to provide antibiotic medication highlights the need of not only choosing appropriate therapeutic substances but also the controlled release of the medicine and its rate of release within the wound area. The results of our study indicate that the use of cefazolin encapsulated polycaprolactone (PCL) microparticles can effectively regulate the application of antibiotic treatment for chronic skin wounds. The results also showed a substantial gradual release of cefazolin from the thermo-responsive Pnipam hydrogel when the wound dressing was subjected to a temperature of 37°C. We believe that the developed flexible smart bandage can have a significant impact on chronic wound healing.

A Water-Soluble Multifunctional Probe for Colorimetric Copper Sensing, Lysosome Labelling and Live-Cell Imaging.

We report a water-soluble fluorescence and colorimetric copper probe (LysoBC1); this system can also serve for lysosome labeling and for the dynamic tracking of Cu2+ in living cells. The sensing mechanism takes advantage of the synergic action by the following three components: i) a lysosome targeting unit, ii) the spirolactam ring-opening for the selective copper chelation and iii) the metal-mediated hydrolysis of the rhodamine moiety for fluorescence enhancement. In aqueous environment the molecule acts as a fluorescent reversible pH sensor and as colorimetric probe for Cu2+ at physiological pH; the hydrolysis of the copper targeting unit resulted in a 50-fold increase of the fluorescence intensity. Most importantly, in vitro cell analyses in undifferentiated (SH SY5Y) and differentiated (d-SH SY5Y) neuroblastoma cells, LysoBC1 is able to selectively accumulate into lysosome while the copper binding ability allowed us to monitor intracellular copper accumulation into lysosome.

A molecule with aggregation-induced emission for the pH sensing and anti-counterfeiting applications

In this paper, a meaningful pH sensor (E)-4-(4-(1,2,2-triphenylvinyl) styryl)quinoline (TPQ) with aggregation-induced emission (AIE) effect was synthesized based on the conjugated 4-(1,2,2-triphenylvinyl)benzaldehyde and 4-methylquinoline connected by a CC bond. The conjugated quinoline moiety acts as a proton acceptor, and the small variations of pH value in the linear range of 4.01–7.03 and 7.96–9.45 can cause obvious fluorescence fluctuations. The TPQ has good selectivity and reversibility in pH detection, and importantly, it can detect pH fluctuations in real-time in practical applications by fluorescent means. Moreover, TPQ can also be used as a potential viscosity fluorescence sensor for organic solvents. In addition, by combining various color changes of TPQ caused by acid, alkali, water and ammonia stimulation under sunlight and 365 nm ultraviolet light irradiation, it provides a novel concealed optical anti-counterfeiting technique with high security. Therefore, TPQ is a multifunctional molecule with great potential for applications in pH, viscosity sensing and anti-counterfeiting.

Sensor model fusion reveals the dynamics of lactobacillus fermentation with real time concentrations of lactic and acetic acids in ensiling of maize and ryegrass

Anaerobic lactobacillus (LAB) fermentation is key to production of silage. Tracking the dynamics of bacterial metabolism is important for the improvement of LAB fermentation and for evaluation of potential additives. This is currently limited by available ex situ analytical methods, while commercial sensors of lactic and acetic acid content remain unavailable. Here we validate an in situ pH sensor and devise a model-sensor package and a mini-fermenter system (1.5 L) for on-line analysis of LAB fermentation. By the fusion of the model based on mirror mapping principle and the time course of pH measured in situ, a general solution of the dynamic accumulation of organic acid (DAOA) and percentage yield of organic acid (PYOA, 0 ∼ 100 %) is obtained as a function of time. We link PYOA to the initial and final values of lactic and acetic concentrations analyzed ex situ to obtain specific solutions for the time courses of lactic and acetic acid production. We demonstrate the model-sensor system with fermentation of both maize and ryegrass, capturing the dynamic patterns of fermentation, including the rapid depletion of O2 in the initial aerobic phase (maize: ≈ 1.5 h, ryegrass: ≈ 9.2 h), the exponential decline of pH (R2 ≥ 0.99, RMSE ≤ 0.043) in the subsequent anaerobic phase, and metabolic feedbacks of pH on instantaneous acid production (ΔpH; inflection at pH 5), and on cumulative yields of total acidity and specific organic acids. These are all previously unavailable data streams.

Tilted fiber Bragg grating pH sensor based on polyaniline reaction deposition film layer

Tilted fiber Bragg grating pH sensor based on polyaniline reaction deposition film layer

Remote Water Quality Monitoring System In Shrimp Ponds With Photovoltaic (PV)-Based Energy Source

Introduction: Shrimp has great potential to be used as a business field in Indonesia. Especially in Parigi Regency itself, there are now many shrimp ponds that can be found because of the benefits obtained, so people are interested in making shrimp farming a livelihood. One of the main problems of shrimp ponds is pond water quality. There are several factors that affect pond water quality, namely water temperature, water pH, and water salinity, good pond water quality management can maintain quality standards and can increase shrimp yield and productivity Method: To facilitate the shrimp farmers, innovations need to be made in order to help the shrimp farmers manage their shrimp ponds, therefore using a remote water quality monitoring was system in shrimp ponds with photovoltaic (PV) based energy sources is expected to be an innovation in managing shrimp ponds, especially in monitoring water quality in shrimp ponds. The monitoring system designed using the NRF24L01 module as a remote communication module, at the research location the distance from the shrimp pond to the house is approximately 100 meters, so the tools that have been designed can facilitate shrimp farmers to monitor the shrimp pond Results and Disscussion: The results of testing the DS18B20 temperature sensor compared with a digital thermometer measuring instrument get an average error of 0.014%. The test results of the pH sensor compared to the pH meter get an average error of 0.026%. TDS sensor test results compared with the TDS meter get an average error of 0.04%. Conclusion: The temperature, pH, and salinity monitoring system uses transmitter and receiver modules, where the transmitter module reads and sends data to the receiver module wirelessly with NRF24L01. Using DS18B20 temperature, pH, and TDS sensors, as well as energy from photovoltaics, this system helps shrimp farmers monitor pond water quality remotely.

Dual-modal fiber-optic sensor for simultaneous pH and temperature monitoring in tumor microenvironment

The tumor microenvironment (TME) is a complex system. Temperature, pH, oxygen content, and other biomarkers comprehensively reflect the growth state of the tumor, necessitating a multi-parameter detection strategy to garner the precise status of tumor for treatment guidance. Fluorescence imaging technology is a promising tool for realizing this goal due to its advantages of low cost, real-time responses, and high sensitivity. However, several limitations, including the shallow penetration depth of fluorescence signals in biological tissues and the potential crosstalk between multiple fluorescence signals, hinder the practical application of current fluorescence imaging technology. In this paper, a dual-mode optical fiber sensor consisting of a fiber fluorescence pH sensor and a fiber Bragg grating (FBG) temperature sensor is presented. The compact sensor uses different principles for pH and temperature monitoring, thus effectively eliminating potential crosstalk between different signals. In addition, its small size allows it to be inserted into deep tissues for detection. The sensor responds quickly to changes in pH.Moreover, the temperature sensitivity of FBG packaged with PDMS is 34 % higher than the uncoated FBG. In vivo experiments confirmed that the sensor can accurately distinguish normal tissues and tumor tissues. The proposed sensor provides a novel way to realize multi-parameter monitoring of tumor microenvironment and improve the specificity of tumor detection.

Comparative Analysis of Symmetrical/Asymmetrical Vertical Electrolyte‐Insulated Semiconductor Tunnel FET for pH Sensor Application

This study investigates symmetrical/asymmetrical vertical electrolyte‐insulated semiconductor Tunnel field effect transistors (TFETs) (SV‐EIS‐TFET/ASV‐EIS‐TFET) for their application as pH biosensors. On the basis of device‐level simulations, the underlying physics of all architectures is explored and the comparative biosensing abilities of pH biosensors are evaluated. A vertical electrolyte Bio‐TFET with overlapping electrodes is presented in this study. The pH response is measured by observing the change in drain current and potential when the pH of the injected solution transitions from a lower to a higher level. As an intrinsic semiconductor material, electrons and holes in the electrolyte represent mobile ions in the solution. The region of the electrolyte has an electron affinity of 1.32 eV, a bandgap of 1.12 eV, and a dielectric constant of 78. Double gate structures raise concerns about correctly aligning the right and left gates because of their sensitivity impact. An analysis of the effect of gate misalignment on biosensor surface potentials, drain currents, and transconductance is presented. Furthermore, pH value ranges of 1–14 are considered for various sensitivity parameters. Simulations are performed using Silvaco TCAD for the SV‐EIS‐TFET and ASV‐EIS‐TFET biosensors.

Bioelectronic Sutures with Electrochemical pH‐Sensing for Long‐Term Monitoring of the Wound Healing Progress

AbstractThe physiological pH level at wound sites is one of the fundamental factors for monitoring wound conditions in clinical practice. To continuously assess the wound conditions, a variety of bioelectronic pH sensors are extensively developed. However, despite significant advances in bioelectronics for wound monitoring, the application of existing bioelectronic devices, primarily designed as bandages or patches, remains challenging for monitoring pH levels in deep wounds. Here, a flexible pH‐sensing suture is introduced that can be simultaneously used as both a precise pH sensor for wound monitoring and a conventional medical suture. The electrochemical pH‐sensing suture comprises Au nanoparticle‐based flexible electrodes functionalized with polyaniline for the working electrode and Ag/AgCl for the reference electrode, seamlessly integrated onto a standard medical suturing thread. This dual‐function sensing suture offers a reliable and high sensitivity of 58.9 mV pH−1, negligible hysteresis, high stability, and excellent selectivity in pH sensing. The biocompatibility of the sensing suture is systematically verified for its in vivo use. To demonstrate the capabilities of the pH‐sensing suture, it is successfully applied to an incision and chronic wound model of mouse to perform continuous and accurate monitoring of the inflammation and healing progress of the wound throughout the healing period.

Investigation of High-Sensitivity pH Sensor Based on Au-Gated AlGaN/GaN Heterostructure

A high-sensitivity pH sensor based on an AlGaN/GaN high-electron mobility transistor (HEMT) with a 10 nm thick Au-gated sensing membrane was investigated. The Au nanolayer as a sensing membrane was deposited by electron-beam evaporation and patterned onto the GaN cap layer, which provides more surface-active sites and a more robust adsorption capacity for hydrogen ions (H+) and hydroxide ions (OH−) and thus the sensitivity of the sensor can be significantly enhanced. A quasi-reference electrode was used to minimize the sensing system for the measurement of the microliter solution. The measurement and analysis results demonstrate that the fabricated sensor exhibits a high potential sensitivity of 58.59 mV/pH, which is very close to the Nernstian limit. The current sensitivity is as high as 372.37 μA/pH in the pH range from 4.0 to 9.18, under a 3.5 V drain-source voltage and a 0 V reference-source voltage. Comparison experiments show that the current sensitivity of the Au-gated sensor can reach 3.9 times that of the SiO2-gated sensor. Dynamic titration experiments reveal the pH sensor’s ability to promptly respond to immediate pH variations. These findings indicate that this pH sensor can meet most application requirements for advanced medical and chemical analysis.

Malassezia responds to environmental pH signals through the conserved Rim/Pal pathway.

During mammalian colonization and infection, microorganisms must be able to rapidly sense and adapt to changing environmental conditions including alterations in extracellular pH. The fungus-specific Rim/Pal signaling pathway is one process that supports microbial adaptation to alkaline pH. This cascading series of interacting proteins terminates in the proteolytic activation of the highly conserved Rim101/PacC protein, a transcription factor that mediates microbial responses that favor survival in neutral/alkaline pH growth conditions, including many mammalian tissues. We identified the putative Rim pathway proteins Rim101 and Rra1 in the human skin colonizing fungus Malassezia sympodialis. Gene deletion by transconjugation and homologous recombination revealed that Rim101 and Rra1 are required for M. sympodialis growth at higher pH. Additionally, comparative transcriptional analysis of the mutant strains compared to wild-type suggested mechanisms for fungal adaptation to alkaline conditions. These pH-sensing signaling proteins are required for optimal growth in a murine model of atopic dermatitis, a pathological condition associated with increased skin pH. Together these data elucidate both conserved and phylum-specific features of microbial adaptation to extracellular stresses.