Temperature sensors, AIMS

During the last years, so-called microhotplates (pHP) have been developed in order to shrink the overall dimensions and to reduce the thermal mass of metal-oxide gas sensors [7,9,15]. Microhotplates consist of a thermally isolated stage with a heater structure, a temperature sensor and a set of contact electrodes for the sensitive layer. By using such microstructures, high operation temperatures can be reached at comparably low power consumption (< 100 mW). Moreover, small time constants on the order of 10 ms enable applying temperature modulation techniques with the aim to improve sensor selectivity and sensitivity. 

Focus on producing pressure sensors with an operating temperature of up to 225°C Semiconductor gas sensors aiming to realize a gas detection system, which is equivalent to or superior to a human sense of smell Sensing elements, devices, instruments, and systems that enable our customers to monitor, protect, control, and validate their critical processes and apphcations Hazard detection and life protection... 

Current developments are aimed at reducing the lower detection limit and at extending the upper ambient temperature limit. The chance to integrate sensors of this type into commercial gas boilers increases with positive results of these efforts. 

For a superior introduction to this difficult topic, try Peter Rock s now classic book, Chemical Thermodynamics, Oxford University Press, Oxford, 1983. The treatment in Temperature Measurement (second edition), by Ludwik Michalski, Joseph McGhee, Krystyna Eckersdorf and Jacek Kucharski, Wiley, New York, 2001, is aimed at engineers manufacturing temperature-measuring machines, such as electrical and optical sensors, but some of its introductory material might help. 

We will consider all the components of this temperature control loop in more detail later in this book. For now we need only appreciate the fact that the automatic control of some variable in a process requires the installation of a sensor, a transmitter, a controller, and a final control element (usually a control valve). Most of this book is aimed at learning how to decide what type of controller should be used and how it should be tuned, i.e., how should the adjustable tuning parameters in the controller be set so that we do a good job of controlling temperature. 

The studies and developments described in this book focus on the latter application, which is the development of sensors, with the aim of generating information from textile wet processes by immersing the developed sensor in the process bath and measuring parameters such as temperature, pH and concentration of the active compound. With this information, it is possible to improve and optimise the envisaged processes. 

Select the aim of the experiment. The aim is essential, even if it looks very simple. It reflects all aspects of the planning. The aim of an experiment consists of the answer to the question of whether zirconia sensors can measure the selected gas concentration under certain environmental conditions (high temperatures, presence of humidity and other gases, etc.). The answer usually is yes or no. The test expenses in this case are insignificant. For example, the aim of the experiment can be the... 

Wearable technology consists of wearable electronics, a term that mainly includes simple and more complex electronic devices and their embedding within textile structures. A good example of the popularity of the research subject is the current Qualcomm Tricorder X-Prize competition for the best portable, wireless device that monitors and diagnoses health conditions (XPRIZE, 2014). Undoubtedly, as the aim is that the device monitors such elements as blood pressure, respiratory rate, and temperature, some of the sensors of the device will come in the form of textile-embedded electronics. 

When an electrical current /q is applied on a thermoresistive flow sensor and its self-Joule heating is maintained at a constant level, any fluid flow through the sensor will cause a shift in its temperature and thus resistance R, respectively. As a result, a decrease in the voltage V (=1qR) of the sensor will be detected. The aim of the thermoresistive flow sensor is to evaluate such changes caused by variations of the flow rate alone. 

---