Definition of a Temperature Sensor and where is it usually used?
Temperature is a measure of the ability of a subject, substance, or
physical system in general – to transfer heat energy to another physical
system. Sensors and sensing devices are used to detect this “movement” of
heat in the physical environment, also known as temperature variation. Different
specialized sensor technologies are used for monitoring regular features of
equipment or environments, and to detect the irregularities within these
General introduction to temperature measurement
Measurement of temperature is critical especially in modern mechanical,
electronic applications, and general processes. There is an increasing number of
applications where detections as precise as a few millikelvins are of
the essence. This enables the necessary precise decision-making
functionality, simple process control of those applications, and/or avoiding the
Specifically, temperature measurement is of utmost importance within various
domains such as building steel and petrochemicals, industrial applications (for
process control, for triggering preventive and predictive maintenance tasks), healthcare and medical
research (continuous temperature monitoring), as well as smart construction,
smart agriculture, and smart consumer goods.
Essentially, temperature is a measure of the ability of a
subject, substance, or physical system in general – to transfer heat energy
to another physical system
By definition – in a context of a mechanical application – temperature
variation in the mechanical parts is the “movement” of heat in the
physical environment for various reasons (Normality: standard heat of
an electric motor that is properly managed by its cooler, Abnormal: Due to
improper lubrication, bearing failure, extra workload – overheating of the
In most of the above-mentioned applications (industrial, commercial,
etc.), the measurement point is frequently far away from the indication or
control point of the sensors. Such applications are unsuitable for
using direct indicating standard thermometers, these require high
precision Temperature Measurement Systems (mostly there are also
requirements for these systems to be wireless).
These devices are usually meant to convert temperature into another form, an
electrical signal, for example – to be able to detect the needed data.
Temperature sensors like resistance temperature detectors (RTDs), thermistors,
thermocouples, LM35, etc. are a standard choice for these applications. These
sensors have the ability to measure temperature through sensing in
Conventionally or Commercially Available Temperature Sensors
The following types of sensors are more commonly used for temperature
resistance temperature devices (RTD),
infrared thermometers (these are rather common in the non-contact
temperature measurement sensors industry and are subdivided into spot and area
Most of these sensors require contact between the sensor and the subject of
measurement, and some, non-contact ones are compromised by the physical
environment(dust, emissivity, etc)
The temperature range of these sensors varies from −100 to 300 °C, the
accuracy is moderate ranging in between 0.1 to 1.5 °C, has a rather
low cost, and isn’t complicated to implement. Additionally
are rather small – the diameter being 0.4 – 2.5 mm. Thermistors may be
found in everyday appliances: fire alarms, ovens, refrigerators, digital
thermometers, in many automotive applications to measure temperature, etc.
However, there are some disadvantages coming with these sensors as well:
non-linearity; limited range; self-heating; current source required;
These are known for their ruggedness, self-powered quality, wide
temperature ranges (-270 – 2300 °C). Thermocouples are widely used
in applications from home appliances to industrials (temperature measurement for
kilns, gas turbine exhaust, diesel engines, and other industrial processes),
etc. At the same time, it comes with some limitations such as lower
accuracy levels (0.5 to 5 °C), low sensitivity/stability, the
necessity for contact, etc.
One of the main advantages of IR thermometers is that they detect the thermal
radiant power, which is emitted by the measurement subject and the surrounding
surface. This means that there is no contact necessary between
the actual device and the measurement subject. These are fast responses;
provide good stability; repeatability; no oxidation impact;
temperature measurement range of −40 to 3 000 °C.
Due to the above-mentioned advantages, these sensors are used in
applications such as heating and air conditioning (to detect insulation
breakdown, heat loss/gain, furnace/duct leakage, industrial/electrical – to
monitor motor/engine cooling systems performance, boiler operations, steam
systems and detection of hot spots in electrical systems and panels, etc –
you can read more about it in this article).
Some of the disadvantages associated with these sensors are the low
accuracy (±2 °C); being easily compromised by the physical
environment difficulties such as smoke, dust, radiation, emissivity as such; at
the same time, these come with relatively complicated
electronics, higher costs, and viewing size restrictions.
Other temperature sensors
There are other sensors, temperature measurement devices, HT measurement
methods as well, that are used less frequently, due to various reasons, the most
common ones being the niche purposes (applications) they serve (i.e. thermopiles
and piezoelectric temperature sensors, bimetallic, chemical molecular
After days of web-surfing, it is still difficult to imagine, with all the
capabilities, accuracies, and strengths, that the conventional sensors, or more
accurately – any one conventional sensor, can satisfy temperature monitoring
needs in accordance with the volatile market demand. Should the
requirements change slightly (the budget, the accuracy needs, the dimension
needs, the non-contact necessity, the stability, etc.) – the customer needs
to employ a different, or additional temperature sensor.
There is a clear gap in the market for a solution that can satisfy
the merged needs of the industries in need of temperature measurement,
as there currently no conventionally introduced unit that can simultaneously
provide the advantages such as contactless(wireless) sensing, resistance,
stability, accuracy, cost-effectivity, miniature dimensions in the scales that
would be at least acceptable.
Of course, when there is a gap within the available scientifically-backed
solutions to solve this “merging issue”, the first instinct should be to
outsource some Research & Development capacity. And it is for this reason
that there are so many new devices coming up in the Temperature Sensor industry.
The industry as such is growing vigorously, with an estimation to reach USD
8.8 billion by 2027, growing at a Compound Annual Growth Rate of 4.8 % during
The only issue here is that the newly-created devices are based on the
already available sensing solutions. Sure, they have improvements in design,
connectivity, etc, however, these are usually the same sensors, or a combination
of multiple of these same sensors made into a new device to serve, again,
a niche application.
And how about the R&D that employs fundamentally new sensing
A relatively young startup from Slovakia seems to have created a unique
sensor that just might have solved the “merging issue” within the
temperature monitoring industry.
RVmagnetics introduces the MicroWire, which is the smallest passive sensor in
the world. The MicroWire sensor acts as a wireless temperature sensor is as thin and elastic as human
hair (diameter of 3–70 µm and length of 1 cm – 4 cm), that can be placed
directly on the subject providing real-time, contactless (no wiring
needed) measurements within up to 10 cm distance.
Being a Research & Development Sensor company, RVmagnetics, essentially
offering a customized alternative sensor based on magnetic
principles, able to measure temperature down to 0,01 °C resolution,
covering the range from –273 °C up to 600 °C. RVmagnetics custom develops
the MicroWire and the sensing system for a specific application, thus meeting
the demand of each customer specifically (the physical design of the final
device is not framed either, as it can be a handheld device for random
measurements or an attached device for constant measurements).
The solution has mostly been capitalized on within the composite
monitoring, rechargeable battery monitoring, electric motor
maintenance, and many more industrial sectors, earning intense involvement and
positive feedback in the E-mobility, Automotive, Oil&GAs, Energy,
Preventive/Predictive Maintenance, MedTech industries.