Development of a vital signs monitoring wireless ear probe

Abstract

The need exists for a mobile and unobtrusive way to continuously monitor vital signs in everyday life. The external ear was investigated as a novel location for a wearable device that monitors core temperature, heart rate, respiratory rate and blood oxygen saturation (SpO2) A proof of concept, called the Ear Monitor, was designed and built to test the feasibility of such a device. A trial was conducted on a group of 16 participants. Measurements were compared to benchmark measurements recorded by commercially available devices. The following results were obtained: Core temperature was measured with a mean error of 0.018 ± 0.516 °C. Heart rate was measured with a mean error of 0.031 ± 0.717 beats per minute. Respiratory rate was measured with a mean error of −0.558 ± 1.406 breaths per minute. Finally, SpO2 was measured with a mean error of −0.22 ± 1.50%. All measurements showed statistically significant correlation with their respective benchmark measurements (p < 0.05), except for SpO2. The latter is due to the absence of measurable SpO2 variations in healthy individuals during the trial. It is concluded that the external ear is a suitable location for measuring core temperature, heart rate and respiratory rate. Further testing is needed to evaluate the SpO2 measurement capabilities of the device.