scholarly journals NIR-emitting aza-BODIPY dyes – new building blocks for broad-range optical pH sensors

The Analyst ◽  
2015 ◽  
Vol 140 (21) ◽  
pp. 7150-7153 ◽  
Author(s):  
Martin Strobl ◽  
Tanja Rappitsch ◽  
Sergey M. Borisov ◽  
Torsten Mayr ◽  
Ingo Klimant
Keyword(s):  
Dynamic Range ◽  
Ph Sensor ◽  
Building Blocks ◽  
Ph Sensors ◽  
Ph Indicators ◽  
Optical Ph Sensors ◽  
Ph Scale ◽  
Extended Dynamic

New NIR-emitting aza-BODIPY indicators which cover the pH scale from 1.5 to 13 are presented and combination of four of these pH indicators yields a pH sensor with an extended dynamic range from pH 2 to 9.

scholarly journals Titanium Nitride Thin Film Based Low-Redox-Interference Potentiometric pH Sensing Electrodes

Sensors ◽  
2020 ◽  
Vol 21 (1) ◽  
pp. 42
Author(s):  
Shimrith Paul Shylendra ◽  
Wade Lonsdale ◽  
Magdalena Wajrak ◽  
Mohammad Nur-E-Alam ◽  
Kamal Alameh
Keyword(s):  
Thin Film ◽  
Titanium Nitride ◽  
Orange Juice ◽  
Ph Sensor ◽  
Reference Electrode ◽  
Cost Effective ◽  
Ph Sensing ◽  
Ph Sensors ◽  
Potential Shift ◽  
Double Junction

In this work, a solid-state potentiometric pH sensor is designed by incorporating a thin film of Radio Frequency Magnetron Sputtered (RFMS) Titanium Nitride (TiN) working electrode and a commercial Ag|AgCl|KCl double junction reference electrode. The sensor shows a linear pH slope of −59.1 mV/pH, R2 = 0.9997, a hysteresis as low as 1.2 mV, and drift below 3.9 mV/h. In addition, the redox interference performance of TiN electrodes is compared with that of Iridium Oxide (IrO2) counterparts. Experimental results show −32 mV potential shift (E0 value) in 1 mM ascorbic acid (reducing agent) for TiN electrodes, and this is significantly lower than the −114 mV potential shift of IrO2 electrodes with sub-Nernstian sensitivity. These results are most encouraging and pave the way towards the development of miniaturized, cost-effective, and robust pH sensors for difficult matrices, such as wine and fresh orange juice.

scholarly journals Ruthenium Oxide pH Sensing for Organs-On-Chip Studies

Proceedings ◽  
2018 ◽  
Vol 2 (13) ◽  
pp. 709 ◽  
Author(s):  
Esther Tanumihardja ◽  
Wouter Olthuis ◽  
Albert van den Berg
Keyword(s):  
Ph Sensor ◽  
Ruthenium Oxide ◽  
Open Circuit ◽  
Biological Medium ◽  
Similar Response ◽  
Ph Sensing ◽  
Ph Sensors ◽  
Cross Sensitivity ◽  
On Chip

A ruthenium oxide (RuOx) electrode is being developed as potentiometric pH sensor for organs-on-chip applications. Open-circuit potential (OCP) of the RuOx electrode showed a response of −58.05 mV/pH, with no cross-sensitivity to potentially interfering/complexing ions (tested were lithium, sulfate, chloride, and calcium ions). Similar response was observed in complex biological medium. The electrode stored in liquid had a long-term drift of −0.8 mV/hour (corresponding to ΔpH of 0.013/hour) and response time in complex biological medium was 3.7 s. Minimum cross-sensitivity to oxygen was observed as the OCP shifted ~3 mV going from deoxygenated to oxygenated solution. This response is one magnitude lower than previously reported for metal- oxide pH sensors. Overall, the RuOx pH sensor has proven to be a suitable pH sensor for organs- on-chip applications.

scholarly journals Photodetector resistant to background light noise with extended dynamic range of input signals

2021 ◽  
pp. 3-8
Author(s):  
V. M. Lipka ◽  
V. V. Ryukhtin ◽  
Yu. G. Dobrovolsky
Keyword(s):  
Dynamic Range ◽  
Automatic Gain Control ◽  
Modulation Frequency ◽  
Low Frequency ◽  
Gain Control ◽  
Ambient Air ◽  
Frequency Range ◽  
Background Light ◽  
Useful Signal ◽  
Extended Dynamic

Measurement of periodic optical information signals in the background light noise with a photodetector with extended dynamic range is an urgent task of modern electronics and thus has become the aim of this study. To increase the dynamic range of the photodetector, a new version of the automatic gain control (AGC) circuit has been developed, which consists of an AGC controller, an output photodetector amplifier and an AGC detector. The authors measured the dynamic range of the photodetector when receiving optical radiation with a wavelength of 1064 nm in the power range from 2.10–8 to 2.10–5 W at a modulation frequency of 20 kHz with the AGC on. Under these conditions, the dynamic range of the photodetector was found to be up to 67 dB. If the AGC was off, the dynamic range did not exceed 30 dB. Thus, the study made it possible to create a photodetector with an extended dynamic range up to 67 dB based on a new version of the AGC circuit. The design of the photodetector allowed choosing a useful signal of a particular modulation frequency in the frequency range from 3 to 45 kHz and effectively suppresses the frequencies caused by optical interference in the low frequency range from the frequency of the input signal of constant amplitude up to 3 kHz inclusive. This compensates the current up to 15 mA, which is equivalent to the power of light interference of about 15 mW. Further research should address the issues of reliability of the proposed photodetector design and optimization of its optical system. The photodetector can be used in geodesy and ambient air quality monitoring.

scholarly journals Optical spectroanalyzer with extended dynamic range for pharmacokinetic investigations of photosensitizers in biotissue

2019 ◽  
Vol 8 (1) ◽  
pp. 46-51 ◽  
Author(s):  
G. A. Meerovich ◽  
E. V. Akhlyustina ◽  
T. A. Savelieva ◽  
K. G. Linkov ◽  
V. B. Loschenov
Keyword(s):  
Dynamic Range ◽  
Spectrum Analyzer ◽  
Pharmacokinetic Studies ◽  
Fluorescent Properties ◽  
Accumulation Time ◽  
Fluorescent Method ◽  
Calibration Samples ◽  
Hardware Circuit ◽  
Improved Accuracy ◽  
Extended Dynamic

Currently, the most promising method for the study of pharmacokinetics of drugs with fluorescent properties is the spectral-fluorescent method. In this article, we propose an algorithm for expanding the dynamic range of the spectrum analyzer by automatically monitoring the maximum spectral density in the recorded fluorescence spectrum and automatically controlled changes in the accumulation time depending on this value, followed by compensation of the output signal with regard to this change, as well as hardware circuit solutions that allow this algorithm.Testing of LESA-01-"Biospeс" spectrum analyzer, upgraded using the proposed approach, was carried out on photosensitizer dispersions based on tetra-3-phenylthiophthalocyanine hydroxyaluminium of various concentrations (from 0.01 mg/l to 50 mg/l), approximately corresponding to the concentrations realized in the process of studying pharmacokinetics in calibration samples and tissues of experimental animals.The proposed solutions that implement the algorithm for recording fluorescence spectra with automatic change of accumulation time depending on the signal level, ensured a significant expansion of the dynamic range of the spectrum analyzer (up to 3.5 orders of magnitude) and improved accuracy in pharmacokinetic studies.

scholarly journals Tryptophan 207 is crucial to the unique properties of the human voltage-gated proton channel, hHV1

2015 ◽  
Vol 146 (5) ◽  
pp. 343-356 ◽  
Author(s):  
Vladimir V. Cherny ◽  
Deri Morgan ◽  
Boris Musset ◽  
Gustavo Chaves ◽  
Susan M.E. Smith ◽  
...  
Keyword(s):  
Transmembrane Helix ◽  
Ph Sensor ◽  
Proton Channel ◽  
Tryptophan Residue ◽  
Ph Sensing ◽  
Ph Sensors ◽  
Voltage Gated ◽  
Karlodinium Veneficum ◽  
Channel Opening ◽  
External Ph

Part of the “signature sequence” that defines the voltage-gated proton channel (HV1) is a tryptophan residue adjacent to the second Arg in the S4 transmembrane helix: RxWRxxR, which is perfectly conserved in all high confidence HV1 genes. Replacing Trp207 in human HV1 (hHV1) with Ala, Ser, or Phe facilitated gating, accelerating channel opening by 100-fold, and closing by 30-fold. Mutant channels opened at more negative voltages than wild-type (WT) channels, indicating that in WT channels, Trp favors a closed state. The Arrhenius activation energy, Ea, for channel opening decreased to 22 kcal/mol from 30–38 kcal/mol for WT, confirming that Trp207 establishes the major energy barrier between closed and open hHV1. Cation–π interaction between Trp207 and Arg211 evidently latches the channel closed. Trp207 mutants lost proton selectivity at pHo >8.0. Finally, gating that depends on the transmembrane pH gradient (ΔpH-dependent gating), a universal feature of HV1 that is essential to its biological functions, was compromised. In the WT hHV1, ΔpH-dependent gating is shown to saturate above pHi or pHo 8, consistent with a single pH sensor with alternating access to internal and external solutions. However, saturation occurred independently of ΔpH, indicating the existence of distinct internal and external pH sensors. In Trp207 mutants, ΔpH-dependent gating saturated at lower pHo but not at lower pHi. That Trp207 mutation selectively alters pHo sensing further supports the existence of distinct internal and external pH sensors. Analogous mutations in HV1 from the unicellular species Karlodinium veneficum and Emiliania huxleyi produced generally similar consequences. Saturation of ΔpH-dependent gating occurred at the same pHo and pHi in HV1 of all three species, suggesting that the same or similar group(s) is involved in pH sensing. Therefore, Trp enables four characteristic properties: slow channel opening, highly temperature-dependent gating kinetics, proton selectivity, and ΔpH-dependent gating.

FBG-Embedded Oblong Diaphragms with Extended Dynamic Range

2018 ◽  
Vol 2 (2) ◽  
pp. 1-4 ◽  
Author(s):  
Arnaldo G. Leal-Junior ◽  
Anselmo Frizera ◽  
Camilo R. Diaz ◽  
Moises R. N. Ribeiro ◽  
Maria Jose Pontes
Keyword(s):  
Dynamic Range ◽  
Extended Dynamic
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