A Blood Pressure Meter (BPM) is a non-invasive device used to measure blood pressure. This application note demonstrates the implementation of a digital blood pressure meter using Microchip’s MCP6N16 instrumentation amplifier and a PIC24FJ128GC010 microcontroller.
The MCP6N16-100 single Instrumentation Amplifier (INA) is used to condition the analog signal acquired from the Wheatstone bridge type of air pressure sensor. The overall INA gain is set at 101 V/V. The output signal of the MCP6N16 is split into two paths. One path, representing the cuff pressure, is connected to the ADC1 channel of the microcontroller. Another path is passed through a 2- pole active high-pass filter with cutoff frequencies of 0.48Hz and 4.8Hz, and a gain of 92. The high-pass filter is formed by one of the microcontroller’s internal operational amplifiers. The output of the high-pass filter, representing the oscillation signal, is sent to the ADC2 channel of the microcontroller.