Handheld sensors

Ymeti, A. Subramaniam, V. Beumer, T. A. M. Kanger, J. S., An ultrasensitive Young interferometer handheld sensor for rapid vims detection, Expert Rev. Med. Devices 2007, 4, 447 454... 

Ideally the sensor should warm up rapidly after power-on, achieving its baseline condition fairly quickly. However, a number of current commercial chemical sensors can take up to 24 h to achieve a stable baseline after long periods of inactivity. Although handheld sensors are often used for short durations, it is preferable to have a sensor that is capable of continuous operation. 

Cloud Computing means that information is permanently stored in servers on the Internet and cached temporarily on clients that include desktops, notebooks, entertainment centers, tablet computers, wall computers, handhelds, sensors, monitors etc (Wikipedia, 2009). For example, Google Apps provides common business applications online that are accessed from a web browser while the software and data are stored on the servers. This is a rather controversial and disturbing concept for privacy and surveillance concerns. 

The main advantages of the current YI sensor are that it is extremely sensitive, is a label-free technique, has multiplexing capabilities, and allows for a compact design. As such it is a good candidate for the development of a reliable handheld... 

Figure 6.5 A fluorinated organically modified silicate doped with [Ru(dpp)3]2+ is a highly sensitive 02 sensor. Fluorine here ensures unprecedented sensitivity and a remarkable stability (2% drift over 6 months). The material has been implemented in sol-gel handheld oxygen sensors that are already commercialized. (Reproduced from ref. 6, with permission.)...

R. M. Bukowski, R. Ciriminna, M. Pagliaro and F. V. Bright, Anal. Chem., 2005, 77, 2670. For instance, a new easy-to-use handheld optical sol-gel oxygen sensor (named FOXY-LITE, see also the website http //www.oceanoptics.com) with a response time of less than one second is commercialized at 1999 since March 2004 by the US company Ocean Optics Ltd. 

The chip is a standalone microsensor system that does not need any external measurement equipment for sensor control and readout. The sensor system chip has been connected to a computer via an f C-to-USB converter box, i.e., in this box is a microcontroller that translates the I C format coming from the chip into USB format for the computer or laptop. The power supply of the chip is also provided by the USB connection. The sensor system can be read out directly by a microcontroller and is, therefore, well suited for handheld devices or distributed sensor networks. 

The discharge temperature should always be measured with a handheld temperature probe because it provides the most accurate measurement. Thermocouple sensors positioned through transfer lines and exposed to the melt stream do not provide an acceptable measurement of the discharge temperature due to the high... 

A handheld thermocouple measurement device and an IR temperature sensor are very important to have for understanding the performance of the extruder. These devices have been discussed previously in this chapter. In many of the case studies presented later, the extrudate temperature was measured by immersing a handheld thermocouple probe into the extrudate. The entire probe length is immersed or draped in the extrudate to minimize heat conduction to cooler parts of the probe. The highest temperature measured is the reported value. If it is unsafe to measure the extrudate temperature using a handheld device, then an IR temperature sensor is used to estimate the discharge temperature. 

At the startup of the line, the extruder was operated at 91 rpm to produce the required rate of 148 kg/h for a specific rate of 1.63 kg/(h-rpm). The temperature of the extrudate was measured through the transfer line wall at 232 °C. Due to process safety constraints the extrudate temperature could not be measured using a handheld temperature sensor. The extrusion rate was required in order to maintain the downstream take-away equipment at its maximum rate. At first the extruder appeared to be operating well except that the specific rate was lower than predicted. That is, the screw was rotated at an rpm that was higher than expected to produce the 148 kg/h. At 91 rpm, the rotational flow rate was calculated at 228 kg/h the specific rotational flow rate was calculated at 2.51 kg/(h-rpm). Thus, the line was operating at only 65% of the rotational flow rate. A barrier design... 

The ideal scenario would be to have the power of a traditional IR analyzer but with the cost and simplicity of a simple filter device, or even better to reduce the size down to that of a sensor (such as the spectral detector mentioned earlier) or a simple handheld device. This is not far-fetched, and with technologies emerging from the telecommunications industry, the life science industry and even nanotechnology, there can be a transition into analyzer opportunities for the future. There is definitely room for a paradigm shift, with the understanding that if an analyzer becomes simpler and less expensive to implement then the role of analyzers/sensor can expand dramatically. With part of this comes the phrase good enough is OK - there is no need for the ultimate in versatility or sophistication. Bottom line is that even in process instrumentation, simple is beautiful. 

Determination of cadmium concentration and pH value in aqueous solutions by means of a handheld light-addressable potentiometric sensor (LAPS) device... 

As described earlier, the basic design of the micropump involves a drug reservoir attached to a pumping device with or without a sensor. The inclusion of a sensor with the device makes it a closed-loop system, where the device can check the levels of marker molecules such as glucose and deliver the therapeutic agent. In many systems the devices are implanted such that the reservoir can be charged when it is exhausted. The device may pump at a basal rate or may be controlled by a circuit connected in a closed loop with a sensor or by a handheld remote control device by the patient. 

Figure 10.9 (a) Diagram of the contact lens glucose sensor with a handheld photofluorometer. 

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