Disclosed herein are gel-based temperature indicators that include a first absorbent substrate having opposing first and second faces and a first gel coupled to the first face. In some embodiments, the first gel is a gel at a first temperature, and the first gel turns to liquid at a second temperature. In some embodiments, the first absorbent substrate is configured to allow the first gel upon turning to liquid to diffuse through the first face toward the second face.

Disclosed herein are gel-based temperature indicators that include a first absorbent substrate having opposing first and second faces and a first gel coupled to the first face. In some embodiments, the first gel is a gel at a first temperature, and the first gel turns to liquid at a second temperature. In some embodiments, the first absorbent substrate is configured to allow the first gel upon turning to liquid to diffuse through the first face toward the second face.

An apparatus, system and method for a time temperature indicator (TTI) which is capable of providing a summary of the time and temperature history of a good to which it is coupled, optionally including with regard to providing an indication as to whether one or more temperature thresholds have been breached. According to other embodiments, the TTI specifically provides an indication as to whether a temperature threshold at or around the freeze point has been breached, optionally even without providing a time and temperature history.

A gas analyzing apparatus includes first and second laser sources that output first and second laser lights, a laser controller that controls the first and second laser sources to vary wavelengths of the first and second laser lights in the respective predetermined wavelength ranges, an optical multiplexer that multiplexes the first and second laser lights to transmit the multiplexed laser light to a target gas, an optical receiver that receives the laser light transmitted through the target gas, and an analyzer that analyzes a temperature and/or a concentration of the target gas based on an electric signal output from the optical receiver. While varying the wavelengths of the laser lights, the laser controller controls amplitudes of the first and second laser lights to differ from each other and varies intensities of the first and second laser lights in the opposite direction.

A gas analyzing apparatus includes first and second laser sources that output first and second laser lights, a laser controller that controls the first and second laser sources to vary wavelengths of the first and second laser lights in the respective predetermined wavelength ranges, an optical multiplexer that multiplexes the first and second laser lights to transmit the multiplexed laser light to a target gas, an optical receiver that receives the laser light transmitted through the target gas, and an analyzer that analyzes a temperature and/or a concentration of the target gas based on an electric signal output from the optical receiver. While varying the wavelengths of the laser lights, the laser controller controls amplitudes of the first and second laser lights to differ from each other and varies intensities of the first and second laser lights in the opposite direction.

An apparatus, system and method for a time temperature indicator (TTI) which is capable of providing a summary of the time and temperature history of a good to which it is coupled, optionally including with regard to providing an indication as to whether one or more temperature thresholds have been breached. According to other embodiments, the TTI specifically provides an indication as to whether a temperature threshold at or around the freeze point has been breached, optionally even without providing a time and temperature history.

A fiber optic thermometer has a hollow body made of material of low thermal expansion and an optical fiber supported by a high thermal expansion intermediate support to form a cantilever section, a fiber optic splitter coupled to a first end of the optical fiber and a light source for directing light into the optical fiber via one branch of the optical splitter. A photodetector receives light conveyed through the optical fiber via the other branch of the optical splitter and measures intensity of the received light. A reflective target supported at a second end of the hollow body is axially aligned with the second end of the optical fiber at room temperature. Upon ambient temperature changes the cantilever section moves relative to the reflective target thereby changing the instantaneous intensity of light reflected by the target into the second end of the optical fiber and measured by the photodetector.

A fiber optic thermometer has a hollow body made of material of low thermal expansion and an optical fiber supported by a high thermal expansion intermediate support to form a cantilever section, a fiber optic splitter coupled to a first end of the optical fiber and a light source for directing light into the optical fiber via one branch of the optical splitter. A photodetector receives light conveyed through the optical fiber via the other branch of the optical splitter and measures intensity of the received light. A reflective target supported at a second end of the hollow body is axially aligned with the second end of the optical fiber at room temperature. Upon ambient temperature changes the cantilever section moves relative to the reflective target thereby changing the instantaneous intensity of light reflected by the target into the second end of the optical fiber and measured by the photodetector.

A light diffusing fiber including one or more segments, and a thermochromic coating on at least a portion of the light diffusing fiber. The thermochromic coating is opaque at a first temperature, and is transparent at a second temperature. A system for detecting the temperature of an apparatus including the apparatus, a light diffusing fiber thermally coupled to the apparatus, and a light source optically coupled to the light diffusing fiber. A method for detecting the temperature of an apparatus including thermally coupling a light diffusing fiber to the apparatus, optically coupling a light source to the light diffusing fiber, and monitoring the light diffusing fiber for transmitted light.

A light diffusing fiber including one or more segments, and a thermochromic coating on at least a portion of the light diffusing fiber. The thermochromic coating is opaque at a first temperature, and is transparent at a second temperature. A system for detecting the temperature of an apparatus including the apparatus, a light diffusing fiber thermally coupled to the apparatus, and a light source optically coupled to the light diffusing fiber. A method for detecting the temperature of an apparatus including thermally coupling a light diffusing fiber to the apparatus, optically coupling a light source to the light diffusing fiber, and monitoring the light diffusing fiber for transmitted light.