To put it simply, a temperature sensor can be considered as the most important part of a temperature monitoring system. It is used to gather data related to temperature fluctuations, which is then converted to a form easily understandable by humans. Data from the source or system is converted to a readable format and an alarm system is activated automatically, which informs the observer about undesired changes and fluctuations.
Such a device comes in different forms. If you are planning to purchase such an item, you should consider the size and design of your monitoring system. Uses of such a device is also another determinant of the type of temperature sensor you should choose. There are a few which are appropriate for home usage, some are for use in offices and commercial areas, still there are a few extremely sensitive sensors, which are used in specific areas like hospitals, labs, blood banks, and for other scientific purposes. A temperature sensor plays a very important role - while it helps in maintaining the right temperature, it also helps in preservation of perishable items, blood, pathological specimens, and food items. Different people have different uses of a temperature sensor - you can use one at home to raise an alarm if suddenly the temperature starts becoming uncomfortable and you are sleeping. The alarm will wake you up and you can take immediate measures to control the environment inside your home. Similarly, it helps a chemist to gather and understand temperature-related data from a complex chemical reaction.
Today a temperature sensor is integrated with mobile technology and alerts and alarms can be sent directly from the system to your smartphone. A good quality temperature sensor will have an automated system which will reduce all chances of human errors. There are basically two types of such sensors - non-contact sensors and contact sensors. Contact ones reach a thermal equilibrium with their environment and measure themselves to know the temperature of their surroundings. The non-contact ones measure the radiation of heat in their surroundings.
If you are buying a temperature sensor for hospital, laboratory or blood bank, make sure that you are purchasing a reputed brand. The ones you buy should be sensitive to even a slight fluctuation in temperature. That is the reason you need to research well before buying such devices. You should check whether the company you are buying a sensor from is a renowned dealer of such equipment.