C-Therm Technologies Ltd.

Thermal Conductivity Instruments for Textiles

Touch. It’s one of our critical senses in perceiving the world – everything from the clothes we wear to the bedding we sleep in. The thermoreceptors in our skin monitor and relay information to our brains about everything we come in contact with. This helps us make decisions about what feels pleasant to the touch and keeps us safe. Human skin is very good at detecting differences in a material’s ability to transfer heat, such as the warmth of a fleece sweater compared to the coolness of leather.

This material property is known as thermal effusivity – as a metric, it can be used to quantify a textile’s ability to exchange thermal energy between skin and fabric. Why is this important? Because human test panels have established a positive correlation between our touch perception of the warmth or coolness of a textile, to its thermal effusivity. In other words, our perception that certain materials will keep us warm or help us cool down is quantifiable. We know this is important in quantifying performance in a wide range of applications – including diapers, activewear, personal protective clothing, upholstery, neoprene dive suits, and bedding. Our skin’s thermoreceptors are giving us good information, though subjective. The C-Therm Tx Platform–quantifies warm and cool feel for you, making what was previously subjective into a metric that can be quantitatively measured. It provides accurate measurements across a range of real world scenarios, including higher humidity environments and under varying compressive loads. The C-Therm Tx measures the science of touch – so you can provide the comfort.

PRINCIPLE OF OPERATION

The C-Therm TCi employs the patented Modified Transient Plane Source (MTPS) technique. The one-sided, interfacial heat reflectance sensor applies a momentary constant heat source to the sample. Thermal conductivity and effusivity are measured directly, providing a detailed overview of the thermal characteristics of the sample.

  1. A known current is applied to the sensor’s spiral heating element, providing a small amount of heat.
  2. The sensor’s guard ring is fired simultaneously supporting a one-dimensional heat exchange between the primary sensor coil and the sample. The current applied to the coil results in a rise in temperature at the interface between the sensor and sample, which induces a change in the voltage drop of the sensor element.
  3. The increase in temperature is monitored with the sensor’s voltage and is used to determine the thermo-physical properties of the sample. The thermal conductivity is inversely proportional to the rate of increase in the sensor voltage (or temperature increase). The voltage rise will be steeper for lower thermal conductivity materials (e.g. foam) and flatter for higher thermal conductivity materials (e.g.metal).