A Low-powered and Wearable Device for Monitoring Sleep through Electrical, Chemical and Motion signals recorded over the head

Sleep perturbations are well-know causes of general uneasiness for many individuals during the daily course of life. Environmental and social stressors derived from the modern lifestyle can affect the quality of sleep, dis-regulating some of the physiological processes taking place during this body and mind resting period. In this paper, we propose a small-form and wearable device for electroencephalography (EEG) monitoring, combined with head motion detection (acceleration) and chemical information collected from off-body sensors targeting sweat pH and cortisol measurements. The incorporated EEG channel has been designed with a cascaded amplification gain of 80 dB, whereas the sensitivity achieved for the developed pH sensor is 48 mV/unit and, for cortisol, a 7 μA current decay is obtained per decade of concentration, within the range from 1 μM to 1 fM. Potential applications of the device include the tracking of the aforementioned chemical analytes during a circadian cycle, which mediate vital brain functions such as neuronal plasticity, maturation, memory formation and cognition, with repercussions in the EEG patterns detected externally. Future incorporation into an eye-shade (EEG and acceleration) and earplug (chemical sensors) will help monitoring the sleep process more easily and accurately, without causing discomfort or pain for patients suffering from sleep-related diseases or other brain conditions.