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

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

Micro Nano Manufacturing Methods for Chemical, Gas and Bio Sensors, Water Purification and Energy Technologies

This chapter reports on the various methods of fabricating and manufacturing micro and nano sensor, membrane and energy devices. Firstly, the characteristic often sought after by scientists and engineers for effective and efficient performance of these technologies were thoroughly discussed in details together with the characterization techniques for evaluating them. Several state-of-the-art fabricating techniques for sensor devices, water and medical based-membranes, solar cells and batteries were also discussed.

The Influence of Plasticizers on Determination of Cationic Surfactants in Pharmaceutical Disinfectants by Direct Potentiometric Surfactant Sensor

Ion selective liquid membrane type membranes are usually made of a PVC, ionophore and a plasticizer. Plasticizers soften the PVC but due to their lipophilicity they influence the ionophore, the ion exchange across the membrane, membrane resistance and consequently the analytical signal. The aim of the research was to investigate the influence of four different plasticizers, in formulation with the same ionophore, on the analytical properties of the sensor membrane towards two often used cationic surfactants, then select the best membrane formulation and test it on real samples of six pharmaceutical disinfectants containing cationic surfactants.

Rancang bangun sensor PH menggunakan gold – extended gate field effect transistor

ABSTRAK Banyak peneliti telah mengembangkan berbagai jenis biosensor, salah satunya sensor pH memanfaatkan MOSFET. Penelitian awal digunakan ISFET sebagai pendeteksi derajat keasamaan, seiring perkembangan teknologi digunakan EGFET sebagai media pendeteksi pH. Karena kelebihan dari EGFET yang lebih stabil dan tahan terhadap gangguan dari luar. Penelitian ini bertujuan untuk mengetahui performansi dari sensor pH berbasis Gold-EGFET dengan tingkat ketebalan lapisan membrane sensor yang berbeda pada pengukuran menggunakan pH buffer yang berbeda. Penelitian ini akan menguji tingkat sensitivitas dan linearitas dari pengukuran pH dengan ketebalan lapisan deteksi dari membrane sensor. ABSTRACT Many researchers have developed various types of biosensors, one of which is a pH sensor utilizing MOSFET. Initial research used ISFET as a detector of the degree of acidity, along with technological developments used EGFET as a pH detection medium because the advantages of EGFET are more stable and resistant to outside interference. This study aims to determine the performance of a Gold-EGFET-based pH sensor with a different level of membrane sensor thickness on measurements using different pH buffers. This study will test the sensitivity and linearity of the pH measurement with the thickness of the detection layer of the sensor membrane.

Rancang Bangun Traffic Light System Tanggap Darurat Berbasis IoT

At crossroads, both crossing three and crossing four which have traffic lights, there is often heavy traffic. Of course this can hamper the performance of priority vehicles that will cross the intersection. To overcome this, the researchers designed a traffic light microcontroller system using a sound sensor. Sound sensor is an automatic identification technology that uses sound waves that hit the sensor membrane which causes the sensor membrane to move which has a small coil behind the membrane up and down then the sensor will be connected to the lights at each airport parking road junction so that the traffic lights of the parking area and arrival terminal or the release changes automatically. The purpose of this study is expected to produce a traffic light system design that utilizes IOT sound sensor technology to the density of vehicles that are at a crossroads either intersection three or intersection four in order to regulate the smooth flow of vehicles and things emergency vehicles (ambulances, fire engines or officials) can work on time and at the maximum, The output produced is a prototype IoT product and publication to journal

Novel Carbon/PEDOT/PSS-Based Screen-Printed Biosensors for Acetylcholine Neurotransmitter and Acetylcholinesterase Detection in Human Serum

New reliable and robust potentiometric ion-selective electrodes were fabricated using poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT/PSS) as the solid contact between the sensing membrane and electrical substrate for an acetylcholine (ACh) bioassay. A film of PEDOT/PSS was deposited on a solid carbon screen-printed platform made from ceramic substrate. The selective materials used in the ion-selective electrode (ISE) sensor membrane were acetylcholinium tetraphenylborate (ACh/TPB/PEDOT/PSS-ISE) (sensor I) and triacetyl-β-cyclodextrin (β-CD/PEDOT/PSS-ISE) (sensor II). The sensors revealed clear enhanced Nernstian response with a cationic slope 56.4 ± 0.6 and 55.3 ± 1.1 mV/decade toward (ACh+) ions over the dynamic linear range 1.0 × 10−6–1 × 10−3 and 2.0 × 10−6–1.0 × 10−3 M at pH 5 with limits of detection 2.0 × 10−7 and 3.2 × 10−7 M for sensors I and II, respectively. The selectivity behavior of both sensors was also tested and the sensors showed a significant high selectivity toward ACh+ over different common organic and inorganic cations. The stability of the potential response for the solid-contact (SC)/ISEs was evaluated using a chronopotentiometric method and compared with that of electrodes prepared without adding the solid-contact material (PEDOT/PSS). Enhanced accuracy, excellent repeatability, good reproducibility, potential stability, and high selectivity and sensitivity were introduced by these cost-effective sensors. The sensors were also used to measure the activity of acetylcholinesterase (AChE). A linear plot between the initial rate of the hydrolysis of ACh+ substrate and enzyme activity held 5.0 × 10−3–5.2 IU∙L−1 of AChE enzyme. Application to acetylcholine determination in human serum was done and the results were compared with the standard colorimetric method.

The Study on the Effect of Wet and Dry Oxidation of Nickel Thin Film on Sensitivity of EGFET Based pH Sensor

The study is based on the use of NiO as an extended gate of field effect transistor (EGFET) using ITO/glass as a substrate for the sensitivity of pH sensor membrane. The NiO thin film was synthesis by wet and dry thermal oxidation method of Nickel metal thin film deposited by RF sputtering. The sensitivity of the NiO membrane was measured and comparatively analysed against the two different oxidation methods. Structural and morphological properties were investigated for both thin films. The sensitivities measurements of the two membranes were made as pH sensors. The results confirmed that NiO membrane grown by dry oxidation had much better sensitivity (87 μA/pH and 54 mV/pH) compared to wet oxidation membrane sample (52 μA/pH and 48 mV/pH).