Sensors noninvasive

Keywords Blood gas analysis Clinical analysis CO2 sensor sensor Noninvasive blood gas sensor O2 sensor... 

Advancing the field of process engineering. Important generic goals for research include the development of separation processes for complex and fragile bioproducts the design of bioreactors for plant and mammalian tissue culture and the development of detailed, continuous control of process parameters by rapid, accurate, and noninvasive sensors and instruments. 

The development of rapid, accurate, and noninvasive online measurement sensors and instraments is a high-priority goal in the commercialization of biotechnology (Figure 3.4). Some of these instraments will build on analytical methods now used in catalysis and other surface sciences, such as... 

The main advantage of this method compared with many other on-line methods for process monitoring is the use of noninvasive, so-called clamp-on sensors which can be easily mounted onto the process eqnip-ment (pipelines, reactors). The sensor, which often is a standard accelerometer, has no moving parts, and can, for example, withstand high temperatnres, a dirty enviromnent and is easy to maintain. The aconstic spectra measured with one sensor will often contain information abont several process-relevant properties and/or analytes which makes it possible to predict several parameters of interest from the same aconstic spectrum. 

Acoustic chemometrics has its greatest benefits in cases where haditional sensors and measurement techniques, such as flow, temperature and pressure transmitters cannot be used. In many processes it is preferable to use noninvasive sensors because invasive sensors may cause disturbances, for example fouling and clogging inside the process equipment such as pipelines, reactors cyclones, etc. In this chapter we concentrate mainly on new industrial applications for acoustic chemomehics, and only discuss the necessary elements of the more technical aspects of the enabling technology below - details can be found in the extensive background literature [3-5],... 

Keywords Chemical sensors Point contact Exhaled air analysis Point-contact spectroscopy Organic conductors Noninvasive diagnostics Chronic dyspepsia... 

This study demonstrates high efficacy and expediency of the TCNQ derivative-based point-contact multistracture as a prospective asset for development of new sensors. The complex character of the sensors response curve and correlation of some response characteristics with different pathological manifestations in human breath, may be further used as a noninvasive diagnostic method alternative to some invasive approaches currently routinely used in clinic. The need for reliable and feasible gas analysis methods functional in presence of atmospheric air, opens opportunities for application of the proposed sensor technique in other spheres of human activity. High sensitivity of the point-contact multistructure enabling analysis of composite gas mixtures, opens up wide possibilities to apply the demonstrated approach for environment and health protection, such as detection of trace amounts... 

The most commonly utilized embedded sensor for temperature distribution mapping is the thermocouple. Wilkinson et al.130 developed a simple, in-situ, and noninvasive method of measuring the temperature distribution of a fuel cell with micro-thermocouples. In this study, thermocouples were located in the landing area of the flow field plates (in contact with the GDL of the MEA) of a fuel cell. The temperature data taken at different locations along the flow channel was then used to find each temperature slope, which in turn were related through mathematical equations to the local current density of each location. Thus, the current density distribution in the fuel cell was determined by simple temperature measurements. The results of this approach are discussed in more detail in Section... 

Figure 3.5 Noninvasive microchip-based nanoflow sensor.

Heise HM, Marbach R, Koschinsky T, Gries FA. Noninvasive blood glucose sensors based on near-infrared spectroscopy. Artificial Organs 1994, 18, 439 -47. 

Kurnik R, Olier J, Waterhouse S, Dunn T, Jayalakshmi Y, Lesho M, Lopatin M, Tamada J, Wei C, Potts R. Application of the mixtures of experts algorithm for signal processing in a noninvasive glucose monitoring system. Sensors and Actuators B 1999, 60, 19-26. 

March WF, Mueller A, Herbrechtsmeier P. Clinical trial of a noninvasive contact lens glucose sensor. Diabetes Technology Therapeutics 2004, 6, 782-789. 

Spectroscopy-based noninvasive analysis for any of the clinical applications noted above provides a means to collect critical analytical information in a novel fashion compared to competing technologies. Alternatively, implants can be used, but operation of implanted sensors is confounded by biologic responses that degrade performance and demand in situ calibration techniques. 

Finally, the robustness of the calibration is a critical parameter that must be established before any noninvasive measurement technology will be useful. Important issues include (1) the ability to collect reliable spectra for each measurement (2) a protocol required to establish a working calibration model (3) time stability of a calibration model and (4) sensitivity of the calibration model to external factors, such as ambient temperature and vibrations. These issues go far beyond demonstrating the feasibility of a noninvasive spectroscopic sensor but pertain to its eventual practical implementation. 

Cameron BD, Baba JS, Cote GL. Measurement of the glucose transport time delay between the blood and aqueous humor of the eye for the eventual development of a noninvasive glucose sensor. Diabetes Technology Therapeutics 2001, 3, 201-207. 

PEBBLEs are water-soluble nanoparticles based on biologically inert matrices of cross-linked polymers, typically poly(acrylamide), poly(decylmethacrylate), silica, or organically modified silicates (ORMOSILs), which encapsulate a fluorescent chemo-sensor and, often, a reference dye. These matrices have been used to make sensors for pH, metal ions, as well as for some nonionic species. The small size of the PEBBLE sensors (from 20 to 600 nm) enables their noninvasive insertion into a living cell, minimizing physical interference. The semipermeable and transparent nature of the matrix allows the analyte to interact with the indicator dye that reports the interaction via a change in the emitted fluorescence. Moreover, when compared to naked chemosensors, nanoparticles can protect the indicator from chemical interferences and minimize its toxicity. Another important feature of PEBBLEs, particularly valuable in intracellular sensing applications, is that the polymer matrix creates a separate... 

All of the aforementioned biosensors are designed for a standard stirred-tank bioreactor they will not work with smaller-scale vessels such as shake flasks. Small noninvasive sensors have been developed to measure D.O. and pC02 inside shake and T-flasks40,41 A D.O. or pC02 detecting patch is placed in the flask, and this patch contains an oxygen or carbon dioxide luminescent dye. The color shifts of these dyes are detected using an external fluorometer. 

Gitis et al. [21] demonstrated the effectiveness of a novel noninvasive instrument called PadProbe , developed by CETR Inc., in monitoring pad surface quality and pad life. PadProbe can be installed on rotational, orbital, and linear type CMP polishers (refer to Fig. 4.10). This sensor can monitor pad surface friction and wear in situ during the conditioning process. The only requirement is that the sensor should be in direct contact with the pad surface. 

Fewer than 10% of patients with diabetes routinely perform SMBG because it is painful and inconvenient Since the 1960s, attempts have been made to develop a painless method for monitoring blood glucose concentrations. Three general approaches have been used, namely implanted sensors, minimally invasive monitoring, and noninvasive monitoring. 

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