Background and aims: The Smart Pad (SP) allows for passive assessment of EE under free-living conditions. The SP works by intelligently air-conditioning a room and simultaneously providing EE estimates via indirect calorimetry (IC). The SP includes a sensing array located in a portable seat cushion, a fan actuation system, and an intelligent algorithm. SP can operate in a regular room conditioned for office work, activity or sleeping. The intelligent algorithm allows for calculations of EE and air exchange rate.The aim of this study is to compare the performance of SP with IC reference instruments.


Methods: The SP was installed in two locations for validation: Arizona State University and Mayo Clinicto probe the validity of the system independent of the physical characteristics of buildings. EE at rest and during activities (e.g. biking) and sleeping were measured for a total of 16 healthy subjects. The assessed EE from the system was compared with those by Reeveu IC Instrument (by Korr, UT), and Ultima CCM™ IC metabolic cart (by Medical Graphics, MN).


Results: The system is mobile and can be installed in any bedroom/office sized space. Regardless of location, the system provides EE measurements with resolutions of 20-30 min, and for each subject was able to discriminate EE for the different MET levels as expected . Subjects from a wide range of ages 22 – 73 years old were able to pass the tests, providing satisfactory feedback on the SP user experience in comparison with reference methods. In addition, correlation coefficients between the data obtained with SP and the reference methods rendered correlation coefficients better than 0.90.


Conclusions: The EE values determined by SP are in good agreement with those given by reference methods. The information collected by the SP in single day with consecutive EE measures, and across multiple days, increases the understanding of EE under free-living conditions with high accuracy and relatively inexpensive cost.