The Different Types Of Digital Thermometers
“Non-invasive” methods include temporal (readings from the temples) and axillary (taken from the armpit), while oral, ear (tympanic) and rectal measurements are classed as “invasive.” All our LCD display thermometers provide a visual reading for accuracy and convenience in Celsius or fahrenheit.
1. Contact Thermometers
Oral Thermometers
Oral thermometers comprise a probe with a stainless steel thermistor tip to conduct body temperature from the patient. Measurements are taken from the mouth, rectum or armpit (axillary).
- The oral method is suitable for patients aged 4+
- An axillary or armpit reading is generally reserved for patients who cannot safely have an oral reading.
- Rectal measurements are most suitable for babies and children up to the age of 3.
Tympanic Ear Thermometers
Employing infrared technology, the ear thermometer is extremely quick and simple to use, and particularly suitable for babies and small children. Used by the NHS, this style of doctor's thermometer offers highly accurate results. Readings can be obtained by scanning the tympanic membrane (eardrum), and gently pull the middle of the earlobe up and back (just back for children under 1 year).
Temporal, Forehead Thermometers
Ideal for paediatric use, the temporal thermometer measures heat flow from the temporal artery in the forehead to the skin and uses it to calculate core body temperature in a matter of seconds. The temporal artery is ideal for this application as it is easy to locate, close to the skin’s surface and has a steady blood flow.
2. Non-Contact, Forehead Thermometers
Also known as remote or forehead thermometers, use infrared radiation emitted from the patient to take a reading, rather than requiring skin contact. Lowering the This means a lower risk of cross-infection between individuals. Readings and results can take place in a matter of seconds making remote thermometers a quick and effective way to efficiently measure multiple, successive temperatures quickly.
Although non-contact, they still require the user to be fairly close to the patient, with the potential for airborne infection spreading between them.
Thermometer technology and how they work
Digital thermometers use different methods to obtain accurate readings, including:
- Peak-hold technology – this locks in the temperature reading when it stops rising. This typically takes 10 to 60 seconds, depending on the type of thermometer and degree of design sophistication. A low-cost, single-use thermometer will take longer to fix a reading than a more highly specified model.
- Predictive technology – this uses software to predict the result based on analysis of the temperature. It’s highly accurate and can produce a reading far more quickly than peak-hold, sometimes in just 1 or 2 seconds.
- Infrared technology – this focuses infrared radiation emitted from the surface of the body onto a thermopile, which converts it into heat and then electric current. The size of this current is fed through proprietary algorithms to produce a core body heat reading. Essentially, the more electricity detected, the warmer the body. It’s not quite as accurate as the previous two methods but does have the advantage of virtually instantaneous results.
