SPI	Serial Peripheral Interface
I²C	Inter-Integrated Circuit
UART	Universal Asynchronous Receiver–Transmitter
CMOS	Complementary Metal Oxide Semiconductor
ICT	Information Communication Technology
RF	Radiofrequency
BPAP	Bilevel Positive Airway Pressure
PPG	Photoplethysmography
SPO2	Blood Oxygen Saturation
ECG	Electrocardiogram
OSA	Obstructive Sleep Apnea
CSA	Central Apnea-Hypopnea
SRBD	Sleep-Related Breathing Disorders
PSG	Polysomnography
CPAP	Continuous Positive Airway Pressure
GSR	Galvanic Skin Response
MEMS	Microelectromechanical Systems
LED	Light Emitting Diode
ANS	Autonomic Nervous System
FDA	Food and Drug Administration
PSD	Power Spectral Density
PWA	Pulse Wave Amplitude
CVD	Cardiovascular Disease
DC	Direct Component (Direct Current is the real meaning, in electronics)
AC	Alternate Component (Alternate Current is the real meaning, in electronics)