Sensing biomedical

In the broad sense, biomedical engineering has existed for millennia. Human beings have always envisioned the integration of humans and technology to increase and enhance human abilities. Prosthetic... 

CdSe thin-film transistors were used in LCDs in 1973. Develc )ed for use in optoelectronic devices, laser diodes, nano-sensing, biomedical imaging and film solar cells. CdSe QDs have potential use in optical devices, such as laser diodes that can cover a large part of the visible spectrum ... 

In the early days of CHEMFET development, the expectations for successful application to a variety of biomedically important sensing applications were high. This was in part due to the fact that CHEMFET s are easily miniaturized (<2 mm surface area) and so are obvious candidates for in vivo applications. This enthusiasm has largely been tempered by the reality that although field-effect tran-... 

Smith A.M., Biomedical sensing using optical fibers, Anal. Proceed. 1985 22 212. 

Ion-selective electrode research for biomedical analysis is no longer the relatively narrow, focused field of identifying and synthesizing ionophores for improved selectivity and the integration of ion-selective electrodes into clinical analyzers and portable instruments. These efforts have matured now to such an extent that they can teach valuable lessons to other chemical sensing fields that are just emerging technologies. 

The electrozone sensing technique, also called the Coulter principle, was originally developed for biomedical applications for counting blood cells. This method counts and sizes particle based on changes in the electrical resistance caused by nonconductive particles suspended in an electrolyte. It presently finds uses in a wide variety of industries, including the food, environmental, coatings, ceramics, and metals industries. 

For the vast majority of sensing applications, the product eCL is less or substantially less than one, for example, in optical fibers L is a few microns, in biomedical applications or research C is usually relatively small. In most practical cases g may be approximated by the first term in the series of Eq. (9.7)... 

The goal of luminescent sensing is perhaps to implement methods and instrumentation capable of performing simple, accurate, and precise measurements in real time. These qualities of sensing systems are especially desirable in the biomedical field in which relevant physiological parameters may change constantly during time expands from a fraction of a second to several hours. 

Finally, we note that future instrument for lifetime-based sensing and imaging can be based on laser diode light sources. At present it is desirable to develop specific probes which can be excited from 630 to 780 nm, the usual range of laser diodes. The use of such probes will allow us to avoid the use of complex laser sources, which should result in the expanded use of fluorescence detection in the chemical and biomedical sensors. 

In the system which uses crystalline alexandrite as the sensor material/381 a measurement reproducibility of 1 °C is achieved over a wide temperature region from 20 to 700°C. The same technique is applied to another fiber optic thermometer system which is designed for biomedical sensing applications and uses LiSrAlF6 Cr3+ as sensor material/391 The standard deviation of the measurement recorded by this system is better than 0.01°C within the 20 Cand 50°C region. 

Of course, the temperature probes discussed could be further classified according to specific applications, e.g., biomedical temperature measurement, high temperature sensing up to >500°C, and the pyrometry range (> 500°C).The development of the temperature probes for such applications cited is discussed where specific applications are concerned. 

Volume 4 is intended to summarize the principles required for these biomedical applications of time-resolved fluorescence spectroscopy. For this reason, many of the chapters describe the development of red/NIR probes and the mechanisms by which analytes interact with the probes and produce spectral changes. Other chapters describe the unique opportunities of red/NIR fluorescence and the types of instruments suitable for such measurements. Also included is a description of the principles of chemical sensing based on lifetimes, and an overview of the ever-important topic of immunoassays. 

Sensors incorporating glass or plastic optical fibers have demonstrated several advantages over electrosensors for biomedical applications. These sensors involve no electrical connections and hence are safe from that standpoint the leads are quite small and flexible they can be incorporated in catheters for multiple sensing where required, they can be implanted for relatively long periods. The fibers are considerably less than 1 millimeter in diameter. Where designed for simplicity, they often can be considered disposable. 

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