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The Transient Plane Source-Effusivity (TPS-EFF) is a portable 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

ASTM D7984-16

Standard Test

-10°C To 50°C


Thermal Effusivity (W√s/m2K) is described as the ability of a material to exchange heat with its surroundings. When you touch a material, heat leaves your hand and goes into the material. If a small amount of heat leaves your hand, the material will feel warm (low effusivity). If a large amount of heat leaves your hand, the material will feel cold (high effusivity).


As the measured thermal effusivity of textiles and fabrics encompasses various modes of heat transport (conductivity, convection and, radiation), the results are referred to as thermal effusance. The measurement of solids, where the main heat transport property is thermal conductivity, results are properly referred to as thermal effusivity.


Features and Capabilities

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 material’s thermal effusivity. For materials of relatively high effusivity, the slope will be lower than materials of low effusivity. 

tps thermal effusivity

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.

  • Follows International Standard ASTM D7984-16
  • Portable, Economical, and Accurate
  • Easy to use
  • Test time 2 and 10 seconds
  • No user calibrations required


Materials Textiles, Fabrics and Solids
Measurement Capabilities 1-Dimensional
Thermal Effusivity Range 35 to 1700 W√s/m2K
Measurement Time 2 and 10 seconds
Reproducibility 2%
Accuracy 5%
Temperature Range1 -10 to 50°C
Minimum Sample Size 35 mm diameter x thickness dependent on Effusivity
Maximum Sample Size Unlimited
Moisture Range 0 to 90% (non-condensing)
Sensor Diameter 30 mm
Standards ASTM D7984-16
Test Method Transient Plane Source (TPS)
1 Requires cooling/heating apparatus.
Testing Sensors
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. The first is with the sample on top of the sensor. The second configuration is the sensor on top of the 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.

Compression, Humidity and Temperature
Compression, Humidity and Temperature

Several applications 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 can measure the effect of compression, humidity, and temperature on a materials thermal effusivity.

Sample Measurements

the sample
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 minute

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 minute

run the experiment

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: < 2 minute

Exporting Results
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 minute


Thermal Effusivity of Multiple Layers and Force
Thermal Effusivity of Multiple Layers and Force

Discovering the feeling decays with test time (touch time) as heat from the sensor (your skin) is dominated by the lower effusivity layer when a more effusive layer is placed over a more insulative layer and measured.

Thermal Conductivity of DIUF Water
Testing Thermal Effusivity with Force

Testing Thermal effusivity of Memory Foam with a compression force of 1 lb and 2 lb

Thermal Conductivity and Viscosity of Carbon Black Heat Transfer Nanofluids
Thermal Conductivity and Viscosity of Carbon Black Heat Transfer Nanofluids

Thermal Conductivity and Viscosity of Carbon Black Heat Transfer Nanofluids


Thermal Effusivity Compressor Stand

TPS-EFF Compressor Stand

Used to compress materials for testing with the TPS-EFF to mimic real situations

TPS-EFF powder adaptor

TPS-EFF Powder Adaptor

For testing small particle sediment and sand to measuring thermal effusivity.