An infrared-based device for non-invasive monitoring of eyelid movement during sleep

The increased movement of eyes and eyelids is characteristic of the rapid eye movement (REM) sleep stage, making it an important indicator in sleep monitoring. A device was designed to detect this activity in a non-invasive way by means of measuring infrared light intensity reflected off the eyelid. The system converts the light intensity into current through a photodetector, performs analog signal processing and analog to digital conversion (ADC). The data is transmitted wirelessly to a computer, where the results can be displayed, stored and analyzed with a dedicated software, which also provides control over the device. The hardware is embedded in a mask, which is put over the patient's eyes. User safety in terms of mechanical, electrical and optical dangers has been ensured. The device was tested on a napping subject.