Temperature sensors are the oldest sensors in use (excluding the magnetic compass), dating back to the very beginning of the scientific age. Early thermometers were introduced in the early 1600s. Around the middle of the 1600s, the need for standards of temperature measurement were voiced by Robert Boyle and others. Shortly after, about 1700, some temperature scales were already in use, devised by Lorenzo Magalotti, Carlo Renaldini, Isaac Newton, and Daniel Fahrenheit. By 1742, all temperature scales, including the Celsius scale (devised in 1742 by Andres Celsius), but excluding the Kelvin scale, were established. Following the work of Leonard Carnot on engines and heat, Lord Kelvin proposed the absolute scale bearing his name in 1848 and established its relation with the Celsius scale. The temperature scales were further developed and improved until the establishment of the International Practical Temperature Scale in 1927, followed by further revisions to improve accuracy.

Chapter Contents:

• 3.1 Introduction
• 3.1.1 Units of Temperature, Thermal Conductivity, Heat, and Heat Capacity
• 3.2 Thermoresistive Sensors: Thermistors, Resistance Temperature Sensors, and Silicon Resistive Sensors
• 3.2.1 Resistance Temperature Detectors
• 3.2.1.1 Self-Heat of RTDs
• 3.2.1.2 Response Time
• 3.2.2 Silicon Resistive Sensors
• 3.2.3 Thermistors
• 3.3 Thermoelectric Sensors
• 3.3.1 Practical Considerations
• 3.3.2 Semiconductor Thermocouples
• 3.3.3 Thermopiles and Thermoelectric Generators
• 3.4 p-n Junction Temperature Sensors
• 3.5 Other Temperature Sensors
• 3.5.1 Optical and Acoustical Sensors
• 3.5.2 Thermomechanical Sensors and Actuators
• 3.6 Problems

Inspec keywords: actuators; temperature sensors; thermometers; temperature measurement

Other keywords: Celsius scale; temperature sensor; thermometer; temperature measurement; thermal actuator; Kelvin scale; engine; magnetic compass; International Practical Temperature Scale

Subjects: Sensing and detecting devices; Thermometry; Thermal variables measurement; Sensing devices and transducers