LED power reduction trade-offs for ambulatory pulse oximetry

The development of ambulatory arterial pulse oximetry is key to longer term monitoring and treatment of cardiovascular and respiratory conditions. The investigation presented in this paper will assist the designer of an ambulatory pulse oximetry monitor in minimizing the overall LED power consumption (P_LED,TOT ) levels by analyzing the lowest achievable limit as constrained by the optical components, circuitry implementation and final SpO2 reading accuracy required. LED duty cycle (D_LED ) reduction and light power (P_LED,TOT ) minimization are proposed as methods to reduce p . Bandwidth and signal quality calculations are carried out in order to determine the required P_LED,TOT as a function of the different noise sources.