Research and Development

Our Scientific Approach Matters 

Kenzen prides itself on its scientific rigor. Your workers’ safety is our #1 priority, and to make sure your workers are safeyou need a solution you can trust. Our features are backed and validated by science 

Our scientific approach is what differentiates Kenzen from its competitors. Our in-house research team comprises experts in heat stress physiology and data science. We also collaboratwith 5 of the top research laboratories in the world to collect the data used to develop our current and new features. These collaborations with leading experts in heat stress physiology mean that each lab utilizes research-grade environmental chambers, processes, and procedures to collect only the highest quality data upon which trusted algorithms can be developed.  

Through these ongoing collaborations over the last year, we have accrued what we believe is the largest dataset in the world, where >70 individuals’ core temperature are continuously monitored throughout their typical day (i.e. >24 h) using gastrointestinal pills. In addition to this dataset, the universities have collected 50 additional trials where subjects executed physical activity protocols in various environmental conditions.  

Most core temperature solutions on the market were built for young healthy men. We are different—individuality matters. As a female-led company, it was important to us to make sure our solution works for all people. Thus, part of our rigorous scientific approach was to make sure our feature datasets included wide variety of critical individual factors that might alter someone’s ability to stay safe in the heat (i.e. age, weight, biological sex, underlying conditions, etc). 

The bullets below call out just a few metric detailing our robust dataset which includes a range of environmental conditions, individual characteristics and activities, to ensure that our solution keeps everyone safe: 

  • >100,000 minutes of ground truth core temperature data (via rectal probe or gastrointestinal pill) while wearing the Kenzen device 
  • >75 unique subjects (with an equal number of males & females) 
  • A large age range of subjects: 18-62 years 
  • Wide range of weight and height: 48-117 kg and 149-194 cm, respectively 
  • >120 trials with a variety of activities: resting, sleeping, walking, running, working, cycling 
  • Ground truth core temperature range of 36.0-40.2°C 
  • Environmental conditions ranging from cool & dry to hot & humid  

 

As a result of our scientific approach, we are proud to announce that our core temperature accuracy that meets the accuracy criteria set forth by the heat stress experts in the field1:  

  • Mean absolute error (i.e. MAE) < 0.3°C 
  • Pearson r correlation coefficient ≥0.7 (strong correlation) 
  • Root mean squared error (RMSE) of 0.3°C 

 

Accuracy of Kenzen core temperature vs. ground truth core temperature (105,532 minutes of activity and >75 subjects): 

  • MAE = 0.3°C 
  • Pearson = 0.8 
  • Mean bias = -0.01°C 
  • RMSE = 0.3°C 

 

Spot-check temperature devices (e.g. oral thermometer or infrared thermometer) simply don’t work when people are working or exercising in the heat. Below is a table of the accuracy of these spot-check temperature devices compared to a ground truth rectal probe, along with the Kenzen device. 

 

Table 1. Typical bias values during exercise in the heat (compared to the rectal probe) for commonly used devices on the market 

Device 

Bias/MAE (°C) 

Gastrointestinal temp (pill)* 

-0.2 

Kenzen device † 

0.3 

Forehead Sticker* 

-0.6 

Forehead thermometer* 

-1.5 

Oral thermometer* 

-1.7 

Armpit thermometer* 

-2.1 

Ear thermometer* 

-1.0 

 

*Note that for all devices, other than the Kenzen device, we are reporting the mean bias in comparison to rectal temperature during exercise in the heat as reported in reference 1 We are reporting the overall MAE for the Kenzen device here because the mean bias is very low for our device (-0.01) because we equally overestimate and underestimate CBT, and so the bias does not fully capture the Kenzen accuracy in comparison to these devices. However, even in reporting the MAE, Kenzen is the only valid device during exercise in the heat (other GI temperature) that meets the accuracy criteria. The Kenzen device also has the lowest error compared to all other devices. During exercise in the heat, the other devices that are non-invasive largely underestimate ground truth core body temperature and are not acceptable measurements of core temperature. 

 

1. Casa, Douglas J., et al. "Validity of devices that assess body temperature during outdoor exercise in the heat." Journal of athletic training 42.3 (2007): 333.