Feasibility study and prototyping of electroencephalography and electrooculography wireless sensor for sleep monitoring

The context of this thesis work is the telehealth monitoring with specific focus on remote sleep monitoring. This thesis activity was carried out in the Advanced System Technology (AST) division, Remote Monitoring group of STMicroelectronics, which is involved in the study and development of wearable devices for the collection of physiological parameters. The main objective of this tesis is the development of an EEG wireless sensor, to be integrated in a wireless sensor network for sleep monitoring, with the minimum channels number required to characterize the microstructure of sleep, by using a chip developed at STMicroelectronics, HM121, not yet available on the market. The chip HM121 is an integrated bio-potential acquisition system originally designed for the ECG and body-impedance signal acquisition. A preliminary feasibility study is conduced to define the minimum number of channels necessary for the sleep classification purpose and from this analysis the choise of using one EEG channel and one EOG channel is proposed and the electrodes positioning is defined. Thus the design of a low-noise pre-amplifier stage to adapt the input dynamic range of EEG and EOG signals to that of HM121 is developed. Design, simulations and noise analysis of the pre-amplifier stage are developed. The prototyping stage consists in the assembly of the pre-amplifier on a matrix board and in its connection to a PCB board developed at STMicroelectronics which embeds HM121 and other sensors. Assembly strategies and bench tests to validate the system functioning are completely conduced. The developed hardware platform allows the data transmission to a smartphone App through a Bluetooth module. The package for the prototype is developed and the wearability of the system is studied. The in-vivo tests during sleep nights show that the system is able to clearly distinguish the typical waveforms of the different sleep stages. The developed prototype is a wearable and unobtrusive device, easily self-applicable by untrained people on the forehead and the essential aspect is that it may substitute the classical and extremely cumbersome polysomnography exam for sleep monitoring