Measurement of pulse transit time using AT90S8535 microcontroller

The long patient waiting list for sleep breathing disorders investigation in sleep laboratories has made ambulatory monitoring more popular. Pulse transit time (PTT) has shown its potentials in respiratory studies. Currently, PTT can only be performed with complex acquisition systems in tertiary centres. This paper presents a prototype design of a stand-alone monitoring device that outputs PTT measurements both in analogue and digital format to existing acquisition system and a personal computer respectively to enable further analysis. A dedicated AT90S8535 based microcontroller and its associated peripherals are employed for the hardware. The details of its interface evaluated results are explained in this paper.