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Understanding the Role of Existing Technology in the Fight Against COVID-19
Published in Ram Shringar Raw, Vishal Jain, Sanjoy Das, Meenakshi Sharma, Pandemic Detection and Analysis Through Smart Computing Technologies, 2022
The working principle of an IR thermometer is based on the black body radiations. All bodies with mass emit heat energy in the IR region. The IR thermometer detects the heat energy (IR electromagnetic radiations) emitted by an object and compares it with the IR radiations coming from the surrounding environment. The difference between the two incoming radiations gives a measure of the temperature. According to Stefan-Boltzmann’s law, the power radiated by a body is proportional to the fourth power of temperature. The main components of an IR thermometer comprise a lens and a detector. The lens focuses the incoming radiations onto the detector, which converts the radiations into electrical energy. The detector used in the IR thermometer is a thermopile. A thermopile consists of several thermocouples connected in series. The thermopile absorbs the IR radiations, which heats up one set of the thermocouple junctions. The other junctions are maintained at a reference temperature. The difference in the heat energy (or temperature) between the two layers of thermopile generates an electrical signal. An output voltage is generated which is proportional to the temperature difference, and thus gives the required temperature reading. The total process of temperature measurement takes a few seconds, thus making IR thermometers much faster than conventional medical thermometers. The schematic diagram showing the working of an IR thermometer is shown in Figure 2.1(a).
Distributed Sensor Arrays
Published in Prabhakar S. Naidu, Distributed Sensor Arrays Localization, 2017
Thermal sensors (e.g., thermocouple) utilize the Seebeck effect in which thermoelectric force is generated due to the temperature difference at the contact points between two different metals. The Seebeck coefficient mostly depends upon the composition of conductors. It may vary in the range of 100 µV/K to 1000 µV/K (K for Kelvin scale). A thermocouple is often used to measure high temperature, holding the cold junction at a known temperature. A thermopile is created by serially connecting thermocouples consisting of N + poly Si, P + poly Si, and Al (aluminum). A thermopile generates output voltages proportional to the local temperature differences. When connected serially, the voltage output between the first and last thermocouple is the sum of outputs of all thermocouples. Each thermocouple acts as a source of electromotive force (emf). By creating hot junctions on highly heat-resistant dielectric membranes, and cold junctions on highly heat-conductive silicon, it is possible to achieve a high-speed response and high-energy conversion efficiency.
Measurements
Published in J. R. Coaton, A. M. Marsden, Lamps and Lighting, 2012
Those most frequently used are thermocouples, thermopiles and bolometers. A thermocouple or thermopile converts thermal energy into electrical energy by means of the Seebeck effect. A thermocouple consists of a circuit of two dissimilar metals or semiconductors. One of the junctions is blackened and absorbs the radiation to be measured, whereas the other junction is screened and remains cool. The current generated is proportional to the temperature difference between the two junctions and to the flux absorbed. A thermocouple employs one junction whereas a thermopile consists of a number of thermocouples connected together in series, with all the blackened junctions grouped together to make a target. Essentially a bolometer consists of two small thin ribbons of blackened metal forming two arms of a Wheatstone bridge. One of the ribbons is exposed to radiation and becomes heated, changing its resistance and upsetting the balance of the bridge; the other ribbon is screened from the radiation.
Sm-Co-based amorphous alloy films for zero-field operation of transverse thermoelectric generation
Published in Science and Technology of Advanced Materials, 2022
Rajkumar Modak, Yuya Sakuraba, Takamasa Hirai, Takashi Yagi, Hossein Sepehri-Amin, Weinan Zhou, Hiroto Masuda, Takeshi Seki, Koki Takanashi, Tadakatsu Ohkubo, Ken-ichi Uchida
Figure 6 (a) represents a schematic view of the prototypical ANE-based heat flux sensor having a thermopile structure where the one end of a magnetic wire is electrically connected to the opposite end of an adjacent magnetic wire. In this thermopile structure, when the magnetization (heat flux) is along the width (thickness) direction of the wires, the ANE voltage is generated along the length of the wires and the total output voltage gets multiplied by the number of magnetic wires. However, when we pattern the magnetic film into a wire structure, the strong in-plane demagnetization field reduces the remanent magnetization which causes the reduction of the sensitivity of the device at zero field [24]. For wide applications of heat-flux sensors, the zero-field operation is necessary, and the present SmCo-based amorphous films with strong out-of-plane anisotropy (see Figure 5 (c)) are promising candidates.
A Machine Learning Approach to the Smartwatch-based Epileptic Seizure Detection System
Published in IETE Journal of Research, 2022
Gaurav G, Rahul Shukla, Gagandeep Singh, Ashish Kumar Sahani
Since a single sensor is not capable enough to detect all kinds of seizures, thereby many studies have proposed to use of multi-modal sensor systems [26–29]. The Empatica E4 wristband is a unique multimodal wearable system that provides the multi-resolution signal of PPG, three-axis accelerometer, EDA, and temperature (infrared thermopile) [30]. At MIT and Boston Children’s hospital, an early machine learning method for seizure detection and alert system was developed using an Empatica E4 wristband with an accelerometer signal and electrodermal activity signal [29]. It is a multiresolution sensor system with design consideration taken for long-term patient vitals monitoring in clinical as well as non-clinical environment and flexibility to monitor, process, or analyze the raw signals.
Experimental Investigation of Thermal Properties of Materials Used to Develop Cryopump
Published in Fusion Science and Technology, 2021
R. Gangradey, J. Mishra, S. Mukherjee, P. Nayak, P. Panchal, J. Agarwal, V. Gupta
The emissivity of the material plays a role in the estimation of radiation heat loads. Its value varies from 0 to 1. For emissivity measurement, a D&S Emissometer20 is used (Fig. 6). It has a differential thermopile with low- and high-emittance areas.21 In this system, the differential temperature is created by heating the detector to 82°C so that the sample to be measured does not have to be heated. Voltage is generated in the thermopile due to the temperature difference between the low- and high-emittance areas because of the different absorption and emission of the radiations. The voltage generated is directly proportional to the emissivity of the surface faced by the detector. This method of measuring emittance is not an absolute method; it is a comparative method and hence requires calibration before measurement. For calibration, two standard samples, one of high emittance and one of low emittance, are used. The method gives the value of emissivity at room temperature.