The Simons Observatory will use Transition Edge Sensor (TES) bolometers. Some technologies used are HEMT, MMIC, SIS and bolometers. Bolometers and microbolometers are based on changes in resistance. His graduate work focused mainly on aluminum hot-electron bolometers for microwave astronomy. The sensing unit was a bolometers made from germanium. The same effect is used in ultrasensitive bolometers made from superconducting materials. Examples of devices where phonon noise is important include bolometers and calorimeters. Hence, HgCdTe detectors are relatively heavy compared to bolometers and require maintenance. These bolometers are kept at a temperature of 0.27 kelvin. Potential applications that have been demonstrated include light emitting diodes (LEDs), bolometers and optoelectronic memory. Approximately 60,000 bolometers with roughly half on the LAT and the rest on the SATs. The experiment uses bolometers for radiation detection. Today, most bolometers use semiconductor or superconductor absorptive elements rather than metals. The bolometers are sensitive not only to light but to every form of energy. Bolometers are directly sensitive to the energy left inside the absorber.