Design and Evaluation of an Instrumented Floor Tile for Measuring Older Adults’ Cardiac Function at Home

Background Home monitoring of chronic diseases among older adults has been the focus of recent research as early detection of adverse events allows better management.Conventional medical devices require active engagement from the users, making it difficult to implement for people who have challenges with using technology, such as people with cognitive impairment.While smart homes are a promising emerging approach to tackle this challenge, related technologies are still cumbersome to use.In response to this challenge, we present a zero-effort instrumented floor tile that could be permanently installed in a bathroom or kitchen to measure a person's ballistocardiogram (BCG) and electrocardiogram (ECG) signals as part of a smart home system.Methods The floor tile contained four load cells in a Wheatstone bridge configuration to measure BCG while standing and four electrodes to measure ECG while sitting.Both the BCG and ECG were amplified by 100dB and had rails of -9V to +9V.BCG and ECG from the tile were sampled at 128Hz.To validate the device, data were collected from 60 healthy adults in various sitting and standing scenarios.The ECG and BCG obtained from the tile compared to RR-intervals (time duration between two successive ECG R-peaks) and heartrate obtained from chest ECG collected with (gold standard) gelbased electrodes.The RJ-interval (time duration between the ECG R-peak and the highest peak in the BCG signal called the J-peak) was also examined for an induced change in blood pressure.Results The ECG signal measured from the tile in the sitting position had 89% agreement with the gold standard ECG.Heart rate based on BCG had an error of 1.8 ± 4.3% compared to that of the gold standard ECG.The RJ-interval was reduced postinduced blood pressure change and returned to the baseline after a few seconds, which is comparable to the literature.Conclusions The prototype tile presented in this work shows promising results as a zero-effort component in a smart home vitals monitoring system.With further modification and addition of intelligent algorithms, we believe the tile presented could collect ECG and BCG from older adults in a non-clinical setting.