Low-Power Blood Pressure Meter Demonstration

A blood pressure meter, or sphygmomanometer, is a device that is used to measure blood pressure. The meter is used with an inflatable cuff for restricting blood flow and a pump to inflate the cuff. Digital blood pressure meters typically measure both systolic and diastolic pressures by an oscillometric detection method, using a piezoelectric pressure sensor.

Our Low-Power Blood Pressure Meter Demonstration was implemented using the system-on-a-chip PIC24FJ128GC010 MCU. The features of this MCU are:

• eXtreme Low Power (XLP) technology
  • 18 nA Deep Sleep mode
  • 240 nA Watchdog Timer (WDT) operation in Deep Sleep modes
  • 180 µA/MHz Run mode
• 16-bit delta-sigma Analog-to-Digital Converter (ADC): two differential channels
• 12-bit 10 Msps pipeline ADC: 50 channels
• Two 10-bit 1 Msps Digital-to-Analog Converters (DACs)
• Two operational amplifiers
• Three comparators
• Three voltage references
• Charge Time Measurement Unit (CTMU)
• USB with device/host/OTG support with active clock tuning (no crystal required)
• Segmented LCD driver with charge pump

Energizer^® Application Support (from the makers of Energizer batteries) did extensive testing of our Low-Power Blood Pressure Meter Demonstration. From that testing, they were able to estimate that the long-term battery life of our Low-Power Blood Pressure Meter Demonstration was 700 uses when used with four standard alkaline AAA batteries. In contrast, they also ran the same tests on five popular name-brand blood pressure meters that don't use Microchip parts. For these meters, the battery life ranged from over 500 uses down to 75 uses with four standard alkaline AAA batteries. With 700 uses, the Microchip solution demonstrated a significant increase in battery life. Additionally, Energizer found that by using their Ultimate Lithium AAA batteries in the demonstration, the number of uses increased to almost 1,200.