Proof-of-Concept (PoC) Experiment

In support of the crucial role of temperature in the development of pressure ulcers, VitalWear has carried out a proof-of-concept experiment that demonstrates the capability of the VitalWear sensor sheet to measure temperature variations on healthy human skin.

SETUP

The experiment was set up as follows: The temperature of the skin of a healthy test subject was measured before and after the application of thermal cream with the VitalWear sensor. For reference, images with a thermographic camera were recorded several times throughout the experiment.

PREPARATION PHASE

During the first phase of the experiment, the forearm was placed on the sensor sheet, which, as a result of the transfer of body temperature, produced a temperature increase to all sensors. The measured increase was up to 10°C compared to the ambient temperature at the start of the experiment, which is in agreement with the recording of the thermal camera.

EXPERIMENT

After the temperature reached steady state, thermal cream was applied to a part of the forearm which roughly covered four of the sensors. The skin covering the remaining four sensors was not treated, and produced the “reference” signal.

After the application of thermal cream, the temperature of the treated area rose by a maximum of 3.6°C, which was followed by a slow decay to almost the initial temperature level as the effect of the thermal cream gradually faded. During this timeframe the temperature of the reference area stayed roughly constant, as indicated in the graph below.

The temperature differences recorded with the VitalWear sensor and the thermal camera remained in good agreement throughout the experiment.

As an example, at 16:37 the thermal camera recorded a difference of roughly 2.6°C while the VitalWear sensor recorded a difference of 2.7°C between the treated part and untreated part of the forearm.

The experiment was stopped after 3.5 hours, when the temperature difference of about 1.6°C was still present.

Throughout this experiment, the monitored pressure data has been recorded as well. However, as pressure information has not been the focus of this specific experiment, it is not reported here.

CONCLUSION

In conclusion, with this experiment VitalWear demonstrates that its prototype sensor is able to accurately measure temperature variations on human skin, which are similar to the ones produced during the early stages of pressure ulcers.