Design And Application Of A Flexible Wearable Brain Oxygen Monitoring Device

Cerebral oxygen signal can effectively reflect the health status of the human body,continuous and accurate cerebral oxygen monitoring is of great significance for clinical disease diagnosis.Functional near infrared spectroscopy(f NIRS)can be used to measure the hemoglobin concentration parameters of brain tissue noninvasively and in real time.However,limited by cumbersome equipment,high price and uncomfortable wear,conventional f NIRS monitoring systems still cannot achieve continuous and long-term monitoring.In this work,a flexible and wearable long-term monitoring system is developed featured with cost efficiency,simple preparation and light weight,which consists of a pair of light-emitting diodes(LEDs)and a photodetector(PD).The experimental results show that the device can effectively measure the change of hemoglobin concentration caused by neural activity.The main research contents and experimental results of this paper are as follows:1.Design a kind of not sensitive strain of the triangle serpentine interconnection lines to connect to the functional components,reduce the stretch of flexible circuit impedance mismatch,power change and the signal distortion problem.In terms of process,laser cutting is used instead of lithography,which greatly improves production efficiency and reduces preparation costs,allowing the device to have a wider range of applications;the flexible packaging of the device with Parylene further improves the stability of the device without affecting the optical path of the components.2.A series of performance tests were conducted on the f NIRS system to measure the Safety,reliability and stability over time of the system.Based on the luminous power of the light source and the variation of temperature with current,a suitable input current is determined.The long time working stability of the system was measured.The device operated for 7 hours continuously,and the voltage value changed less than 3%.The bending performance and reliability of the device were measured,and the device was bent for 2000 times on the stretching machine to test the luminescent power of the LED and the voltage value of PD.The calculated LED luminous power changes were1.89% and 1.9%,and PD voltage changes were 0.9%.It shows that the device has good stability.3.Validity verification,we first set up the vivo model test,which has higher controllability compared with the in vivo experiment and will not be disturbed by physiological changes.The experimental results preliminarily verify the effectiveness of the device,and showed high sensitivity.Forearm blockade,Valsalva,and Hand-grip experiments were performed,the results were consistent with commercial devices.The results show that the system can accurately measure the change of hemoglobin concentration.The flexible f NIRS system here not only provides a simple preparation process,but also provides new ideas for daily brain state monitoring and long-term clinical monitoring.