Microchannel cooling for the LHCb VELO Upgrade I

The LHCb VELO Upgrade I, currently being installed for the 2022 start of LHC Run 3, uses silicon microchannel coolers with internally circulating bi-phase \cotwo for thermal control of hybrid pixel modules operating in vacuum. This is the largest scale application of this technology to date. Production of the microchannel coolers was completed in July 2019 and the assembly into cooling structures was completed in September 2021. This paper describes the R\&D path supporting the microchannel production and assembly and the motivation for the design choices. The microchannel coolers have excellent thermal peformance, low and uniform mass, no thermal expansion mismatch with the ASICs and are radiation hard. The fluidic and thermal performance is presented.Comment: 31 pages, 27 figure

General survey and microanalytical aspects of ion-selective electrodes

A survey is presented of recent developments in the field of ion-selective electrodes. Special emphasis is placed on problems of electrode miniaturization and ISFET production. Different electrode types in present use are described and theories for the interpretation of electrode mechanisms are outlined. It is pointed out that the electrode potentials are due to the formation of a space charge. Different applications of ion-selective electrodes are dealt with and the problems connected with the determination of small concentrations are discussed. Attention is given to the selection of conditions under which a reliable measurement of extremely small amounts or extremely small concentrations can be ensured. © 1990 Springer-Verlag

Theoretical Interpretation of Transient Signals Obtained with Precipitate-Based Ion-Selective Electrodes in the Presence of Interfering Ions

Precipitate-based ion-selective electrodes respond to sudden changes in the interfering ion activity with nonmonotonic, overshoot-type transient signals, when a certain amount of primary ion is also present in the solution and when the respective selectivity factor is much less than one. A simplified and more detailed quantitative description of these signals is presented in terms of diffusion processes in the adherent solution layer and of adsorption/desorption equilibria on the electrode membrane surface. The validity of this description is proved by excellent fittings to experimental signals in cases of (I) increasing and decreasing interfering ion activity steps, (ii) subsequent changes in interfering ion activity, (Hi) interfering ion activity steps at different primary ion activity levels. The selectivity factor, the diffusion layer thickness values, and the amount of ions adsorbed or desorbed providing good fitting were in agreement with the experimental values determined by other methods, within the respective experimental and calculation errors. © 1985, American Chemical Society. All rights reserved

Cyclic voltammetry at shallow recessed microdisc electrode: Theoretical and experimental study

This study focuses on the cyclic voltammetry behavior at shallow recessed microdisc electrode, particularly on the transition from cottrellian behavior to steady state behavior. Diffusion to the inlaid and recessed microdisc electrode is simulated. From the shape of the CVs, for a given radius and potential scan rate, the transition time from planar diffusion to hemispherical diffusion presents a minimum as the recess increases. Theoretical prediction was confirmed by fitting the simulated CVs with experimental results. Dimensionless transition scan rate has been defined and determined by simulation for inlaid and recessed microdisc electrodes. © 2009 Elsevier B.V. All rights reserved

Detrimental changes in the composition of hydrogen ion-selective electrode and optode membranes

Derivatives of phenoxazine dyes serve as chromoionophores in the field of chemical sensors. By studying the changes of the distribution of membrane components in ETH 5294 based, pH sensitive, ion-selective membranes using spectroelectrochemical microscopy (SpECM), the decay in the concentration of the protonated chromoionophore was generally much larger than expected upon previous studies. These recorded changes could not be interpreted with the leaching of the protonated or unprotonated forms of ETH 5294 or the tetraphenyl borate derivatives embedded in the membrane. Similarly, the changes could not be explained by the photochemical decomposition of the tetraphenyl borate derivatives (tetraphenyl borate, TPB- or tetrakis(4-chlorophenyl) borate, TpClPB-). The decrease in the absorbance value measured at 660 nm, at the absorbance maximum of the protonated chromoionophore has been linked to the photochemically initiated, singlet oxygen mediated decomposition of ETH 5294. The decomposition occurs only if the wavelength of the illuminating light is larger than ∼580 nm, and the rate of decomposition is facilitated by the presence of certain anions in the membrane (TPB-, and TpClPB-) and in the sample solution (Br-, I-, and Cl-) as they were penetrating the membrane by acid coextraction. On the other hand, the protonated chromoionophore was found to be stable in membranes cast with tetrakis[3,5-bis(trifluoromethyl) phenyl] borate anion (TFPB) or in acidic solutions of NO3-, ClO 4-, SO4-, TFPB- and citrate anions. In comparison to ETH 5294 (chromoionophore I), ETH 2439 (chromoionophore II) was found completely stable, and the decomposition of ETH 5350 (chromoionophore III) was also hardly detectable. In our view, in the light of the experimental results summarized in this study some of the widely accepted views and practices in chromoionophore based sensors research should be changed and some of the results should be reevaluated. © 2005 Elsevier B.V. All rights reserved

A Smart Biosensor-Enabled Intravascular Catheter and Platform for Dynamic Delivery of Propofol to Close the Loop for Total Intravenous Anesthesia

Background: Target-controlled infusion anesthesia is used worldwide to provide user-defined, stable, blood concentrations of propofol for sedation and anesthesia. The drug infusion is controlled by a microprocessor that uses population-based pharmacokinetic data and patient biometrics to estimate the required infusion rate to replace losses from the blood compartment due to drug distribution and metabolism. The objective of the research was to develop and validate a method to detect and quantify propofol levels in the blood, to improve the safety of propofol use, and to demonstrate a pathway for regulatory approval for its use in the USA. Methods: We conceptualized and prototyped a novel smart biosensor-enabled intravenous catheter capable of quantifying propofol at physiologic levels in the blood, in real time. The clinical embodiment of the platform is comprised of a smart biosensor-enabled catheter prototype, a signal generation/detection readout display, and a driving electronics software. The biosensor was validated in vitro using a variety of electrochemical methods in both static and flow systems with biofluids, including blood. Results: We present data demonstrating the experimental detection and quantification of propofol at sub-micromolar concentrations using this biosensor and method. Detection of the drug is rapid and stable with negligible biofouling due to the sensor coating. It shows a linear correlation with mass spectroscopy methods. An intuitive graphical user interface was developed to: (1) detect and quantify the propofol sensor signal, (2) determine the difference between targeted and actual propofol concentration, (3) communicate the variance in real time, and (4) use the output of the controller to drive drug delivery from an in-line syringe pump. The automated delivery and maintenance of propofol levels was demonstrated in a modeled benchtop patient applying the known pharmacokinetics of the drug using published algorithms. Conclusions: We present a proof-of-concept and in vitro validation of accurate electrochemical quantification of propofol directly from the blood and the design and prototyping of a smart, indwelling, biosensor-enabled catheter and demonstrate feedback hardware and software architecture permitting accurate measurement of propofol in blood in real time. The controller platform is shown to permit autonomous, closed-loop delivery of the drug and maintenance of user-defined propofol levels in a dynamic flow model

To the memory of erno{double acute accent} pungor: A subjective view on the history of ion-selective electrodes

In the Mátraf red 08 Symposium on Electrochemical Sensors a session was dedicated to the memory of late Professor Erno{double acute accent} Pungor, the founder and long-term organizer of the Mátrafüred conference series. We all remember him as an inventive scientist with an enthusiastic and witty personality, rich in ideas. Erno{double acute accent} Pungor left his mark in science and on many scientists worldwide. With this contribution, the authors would like to pay tribute to him and acknowledge his outstanding contributions to analytical chemistry, but especially his pioneering works in the field of ion-selective electrodes. © 2009 WILEY-VCH Verlag GmbH&Co

Performance evaluation criteria for preparation and measurement of macro- and microfabricated ion-selective electrodes (IUPAC Technical Report)

Over the last 30 years, IUPAC published several documents with the goal of achieving standardized nomenclature and methodology for Potentiometric ion-selective electrodes (ISEs). The ISE vocabulary was formulated, measurement protocols were suggested, and the selectivity coefficients were compiled. However, in light of new discoveries and experimental possibilities in the field of ISEs, some of the IUPAC recommendations have become outdated. The goal of this technical report is to direct attention to ISE practices and the striking need for updated or refined IUPAC recommendations which are consistent with the state of the art of using macro- and microfabricated planar microelectrodes. Some of these ISE practices have never been addressed by IUPAC but have gained importance with the technological and theoretical developments of recent years. In spite of its recognized importance, a generally acceptable revision of the current IUPAC recommendations is far beyond the scope of this work. © 2008 IUPAC

Spectroscopic method for the determination of the ionic site concentration in solvent polymeric membranes and membrane plasticizers

The built-in site density of either fixed sites or mobile hydrophobic ion sites determines whether a membrane is permselective for cations or anions of the sample. The molar ratio of the ionophore to the intrinsic or added ionic sites in an ion-selective membrane significantly influences the potentiometric response of ionophore-based electrodes. Consequently, full knowledge of the site inventory in an ion-selective membrane may be essential when new, uncharacterized polymers or plasticizers are implemented for ion-selective electrode fabrication. A simple-spectroscopic method was developed for the fast and accurate determination of the ionic site concentration (covalently attached functionalized groups or impurities) in plasticized polymeric membranes and membrane plasticizers. The method is based on the determination of the degree of protonation of hydrogen ion-selective chromoionophores incorporated into these membranes or dissolved in the membrane plasticizers. In electroneutral membranes, the concentration of the positively charged, protonated ionophore and the total concentration of negative sites are equal. The method was applied for the determination of ionic sites (both positively and negatively charged) in PVC materials (different purity grade, and bearing various functional groups), polyurethanes (aliphatic, aromatic, and polycarbonate-based), and selected Fluka plasticizers (2-nitrophenyl octyl ether and 2-ethyl-hexyl sebacate). The technique proved to be appropriate for fast quantification of ionic impurities in hydrophobic, optically transparent materials