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Enabling better global research outcomes in soil, plant & environmental monitoring.

STPSYS05 Surface Thermal Properties measuring SYStem

STPSYS05 is a practical system for measuring the thermal conductivity at the surface of materials. The measurement method has many advantages, and requirements for specimen preparation and dimensions are limited. Performing a measurement is easy and fast: simply place the sensor on a smooth flat surface of your material and you can measure its thermal conductivity. STPSYS05 is suitable for materials in the 0.1 to 15 W/(m∙K) range (see the manual for rated measurement ranges and expected uncertainties). Materials include plastics, stone, rock, composites, soils, pastes and foodstuff.

The STPSYS05 system consists mainly of a Measurement and Control Unit (MCU) and the STP05 sensor. STP05 combines a heater (line source) with two temperature difference sensors (thermopiles) placed on either side of the heater. When STP05 is placed on a specimen and power is applied to the heater, this creates a temperature difference which is measured by the thermopiles. The measurement is steady-state; interpretation is easy. The thermal conductivity is calculated by the software of the MCU from the heater power and the measured temperature differences. In addition to the thermal conductivity, information about the thermal diffusivity and volumic heat capacity can be obtained from the time response of the thermopile signals.

STPSYS05 Advantages

  • Affordable
  • Non-invasive: all that is required is a smooth flat surface over the sensor area and sufficient specimen thickness below that surface. There is no need for specific specimen dimensions.
  • Single-sided testing: only one specimen is required.
  • Fast to work with: smart sensor design reduces sensitivity to thermal shocks and gradients. The time needed to stabilize before a measurement is short, in the order of 5 minutes.
  • Easy-to-analyse steady-state measurement of thermal conductivity.
  • Intuitive and easy to use graphical user interface, accessible using your web browser. No software installation required on your PC.

How to employ STPSYS05

STPSYS05 can be used to measure thermal conductivities in the range from 0.1 to 15 W/(m∙K). In addition to the thermal conductivity, STPSYS05 gives an estimate of the thermal diffusivity.

STP05 sensor is placed on a smooth surface of the material of which the thermal conductivity is to be measured. For higher accuracy results, glycerol may be used as a thermal contact fluid to ensure minimal interfacial thermal resistance between the sensor and the material. The measurement can be monitored and controlled via the MCU.

Calibration & performance assessment

STP05 is supplied with a calibration certificate stating the sensitivity and the thermal resistances of the sensor. For quality assurance purposes, STPSYS05 system includes a calibration reference specimen.

STPSYS05 can be used in laboratory as well as industrial environments. STP05 sensor can be used to perform measurements at temperatures from ‑20 °C to +80 °C and STP05 is protected against ingress of water, rated IP67.


User interface: MCU is a web server

The MCU performs measurements, data storage and calculation of the measurement result. It acts as a web server that can be connected to any local area network. A user interface is available as a web page. Alternatively, the MCU can be connected to a PC via USB. In that case the web page is available via “Ethernet over USB” or a virtual Ethernet link. If you type the MCU’s IP address ( by default) into your web browser, you have access to the user interface.

STP05 sensor for easy-to-use thermal properties measurement

Ordering STPSYS05

STPSYS05 comes with the following:

  • STP05 sensor with protective cap and calibration certificate,
  • a 1.5 m M12-A cable to connect the sensor to the MCU,
  • a calibration reference specimen for calibration purposes,
  • a measurement and control unit (MCU),
  • a power supply.

Ordering STP05 sensor only

STP05 is also available as a “sensor only”. In this configuration the user must provide a stable switchable power supply to power the heater, an Ohm meter to measure the thermistor electrical resistance and a high-resolution voltmeter to measure the thermopile output voltage and voltage across the heater. When ordering an STP05 only, the user is responsible for data analysis.

Measurand thermal conductivity, thermal diffusivity estimate (optional)
STPSYS05 specifications :
Measurand thermal conductivity
Rated measurement range 0.1 to 15 W/(m∙K)
Optional measurand thermal diffusivity estimate
Rated measurement range (0.05 to 1.0) x 10⁻⁶ m²/s (see manual)
Included cable 1 x cable with 2 connectors (1.5 m)
Typical measuring time 5 minutes
STP05 specifications :
Weight 0.34 kg
IP protection class IP67
Connector male 8 pin circular M12-A
Rated operating temperature range -20 °C to +80 °C
Heater line source
Length 0.06 m
Nominal electrical resistance 15 Ω
Temperature difference sensor thermopile
Nominal sensitivity 0.2 mV/K
Thermal resistance nominal parallel 1.90 m∙K/W
Thermal resistance nominal serial 0.022 m∙K/W
Temperature sensor thermistor
Resistance at 25 °C 10 kΩ ± 1 %
β [25 °C/85 °C] factor 3570 K ± 3 %
MCU specifications :
Graphical user interface web page (via MCU)
Connection local area network (LAN) or “Ethernet over USB”
IP protection class IP54
Rated power supply voltage 10 to 16 VDC
Adapter power supply 100 – 240 VAC 50/60 Hz
Rated operating temperature -25 to +50 °C range
Sampling rate 10 Hz
Options STP05 surface thermal properties sensor only
Keyboard/Display for operating the system without a PC