Core Temperature Wearables - Are We There Yet?

Given the advances in consumer wearable technology, it's a fair expectation that those advances would translate to wearables suitable for workers. Sure, occupational settings are more demanding in terms of the 'ruggedisation' required to operate in the hot and humid microclimate proximal to the body. But if heat-exposed workers are to be managed with input from a wearable device, the key requirement is accuracy. So, here's our take on three wearables currently on the market.

CORE by greenTEG AG

CORE claims to be the "only wearable non-invasive, continuous, and accurate Core Body Temperature monitoring solution", estimating core temperature from a rechargeable 5x4cm heat flux and skin temperature sensor (see below). The sensor is attached below the armpit by adhesive patch or a wearable band (like a heart rate monitor). The battery lasts for multiple days when transmitting and for weeks in stand-by mode. The product website claims that "the accuracy of CORE has been validated in an independent clinical study" and provides a "download" validation link that opens five slides from CORE spruiking accuracy but without the associated published independent research. Our disappointment was short-lived as independent research has been published regarding CORE accuracy. The study employed both cool and warm/hot environmental conditions for exercise that produced almost 12,000 data points, including many >38.5ºC, with the researchers stating that "the results obtained do not support the manufacturer’s claim that the CORE sensor provides a valid measure of core body temperature". You can read the full paper here.


Kenzen

Utilising a similar sized sensor (~5x6cm) to CORE that attaches to the upper arm with a band, Kenzen claims its system provides "continuous safety monitoring (that) is both real-time and highly accurate". Evidence is provided to support this claim but not in the form of independent research published in a peer-reviewed journal. The research is a Kenzen sponsored abstract from the Experimental Biology 2021 Meeting. Read the abstract here.


There's a large discrepancy between an abstract and a full research paper. Furthermore, the analysis of data described within the abstract is questionable. Data was collected every 5 minutes and was seemingly averaged each hour as per the graph below. For a product that claims to provide real-time safety monitoring, reporting accuracy based upon hourly data is a strange move. The accuracy of those real-time measurements should be reported and until that's done by independent research, the claim of accuracy cannot be substantiated.

Cosinuss°

Unlike the CORE and Kenzen options, Cosinuss° is an "in-ear" sensor with a battery life of up to 24hrs. Cosinuss° states "Our ergonomic wearables offer a more cost-effective and accurate altern