TPS-EFF Transient Plane Source - Effusivity

A portable effusivity meter that uses a single-sided TPS sensor with test times of 2 and 10 seconds to understand the measurement of comfort with touch time fully.

Best for textiles, fabrics, and solids



Thermal Effusivity (W√s/m²K) is described as a materials ability to exchange heat with its surroundings. Surface haptics is a branch of psychology, describing the sense of touch, localized to the skin surface. The feeling of warmth and coolness (thermal effusivity) makes up the feeling of comfort, or the desired effect, which goes into the touched material surface. This is an important field of measurement for textiles, fabrics and solids.

The TPS-EFF (Transient Plane Source-EFFusivity) is a portable meter for direct determination of thermal effusivity of textiles and other low effusivity materials, in accordance with ASTM D7984-16. With a single measurement of 2 or 10 seconds in duration, materials can be accurately measured for thermal effusivity. The TPS-EFF uses a single-sided 30 mm diameter TPS sensor and short test times, to ensure one-dimensional heat flow. During the measurement, the sensor is heated using a constant current source, while the temperature rise of the sample is simultaneously recorded with time, by monitoring the change in electrical resistance of the wire spiral. The slope of temperature against a special function of time, is used to calculate the thermal effusivity of the material. For materials of relatively high effusivity, the slope will be lower, than materials of low effusivity.

effusivity equation chart

Mathematically, thermal effusivity equates to the square root of the product of thermal conductivity (W/m•K), Density (kg/m³) and Heat Capacity (J/kg•K). For certain materials, like textiles, there are often other modes of heat transfer, such as convection and radiation. These modes of heat transfer alter the thermal conductIVITY to thermal conductANCE. The resulting term used for measurement of materials like this is referred to as Thermal Effusance.



Textiles, Fabrics and Solids

Measurement Capabilities


Thermal Effusivity Range

35 to 1700 W√s/m²K

Measurement Time

2 and 10 seconds





Temperature Range*

-10 to 50°C

Minimum Sample Size

35 mm diameter x thickness dependent on Effusivity

Maximum Sample Size


Moisture Range

0 to 90% (non-condensing)

Sensor Diameter

30 mm


ASTM D7984-16

Test Method

Transient Plane Source (TPS)

*Requires cooling/heating apparatus.

Testing Sensor

Standard TPS-EFF Sensor

Standard TPS-EFF Sensor

The TPS-EFF comes with a standard 30 mm diameter, single-sided sensor for testing textiles, fabrics and solids. The spring loaded sensor can be used in two testing configurations; sample on top of sensor, or sensor on top of sample. At the push of a button, samples can be measured at 2 and 10 second test times. The additional 10 second test time allows for superior characterization of materials feeling of warmth, or coolness. Ambient temperature and results are conveniently displayed on the test screen. Results can then be saved and exported to Excel.

Compression, Humidity and Temperature

Several application and environmental specific conditions can affect the thermal effusivity (feeling of warmth or coolness) of a material. When used with a compression stand and environmental chamber, the TPS-EFF is able measure the effect of compression, humidity and temperature on a materials thermal effusivity.

Measurement Process

tps-eff sample fabric

The Sample

Using the TPS-EFF, samples of unlimited size can be tested; the sample should be at least 30 mm in diameter to allow contact with the TPS-EFF sensor. Measurement of various textiles, fabrics, and solids are possible. Care should be taken to ensure sufficient thickness of the sample, and the divergence technique may be used to confirm this.

Approximate Time: < 1 min.

Place Sample on Sensor

Place Sample on Sensor

Once a sample has been prepared, measurements may be configured in one of two ways; sample placed on top of the sensor or sensor placed on top of the sample.

Approximate Time: < 1 min.



From the portable TPS-EFF, a test time of 2 or 10 seconds may be selected. The test activated with the push of a button.

Approximate Time: < 1 min.

Result Calculations

Result Calculations

Upon completion of tests, temperature and thermal effusivity results are displayed on the screen. Results can then be exported from the TPS-EFF to Excel, via Micro-SD or USB.

Approximate Time: 1 min.


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