Project Descritpion:

The blood pressure tester is an automatic, one-button device that utilizes the oscillometric blood pressure method, and has the capability to wirelessly send data to other terminals for data analysis. The human interface is an upper arm cuff that is used to occlude blood flow to the lower arm. A rubber tube is connected to a ratio metric pressure sensor and transmits air pressure from the cuff with underlying air oscillations made by skin movement from artery movement. A filter and gain topology separates these air oscillations from the cuff pressure signal for use in an oscillometric algorithm which is implemented within the msp430f5438 microprocessor code. The power management topology includes power regulators to provide ample voltage and current to the varying demands of the system while maintaining the device’s low power consumption profile.

As world populations grow and lifestyles change, there will be a growing need for health monitoring. Increased ability to consume as well as physical activity changes are all triggers for preventable diseases. Blood pressure is a major sign of overall health and can provide warning signs for specific diseases based on average pressure ranges of specific patient profiles. The intention for designing a low power, battery operated device with wireless data transfer capability is to provide an easy to use device that can help in distance monitoring of patients. Logging of readings can lead to early detection of potentially fatal diseases. Commercially, a manufacturing company offering a device with such characteristics could easily garner contracts from major healthcare institutions as well as government agencies that understand the implications that major lifestyle changes can have on overall public health and national budgets. Such organizations would be able to monitor health trends daily, interact more frequently with individuals, and institute preventative measures in advance of irreversible damage.

As the blood pressure tester is battery powered its power consumption must be as low as possible. To reach this goal, the design of the device went through various prototypes to minimize its power use. Prototypes improved from their last implementation to further improve on the lower power requirement. Each design included the selection of a low power topology while improving in its use of voltage regulation control together with switching sequences in an effort to avoid scenarios in which all parts would be consuming maximum power at the same time; much more than simply current and voltage requirements were researched during the design process regarding power. The analog signal chain, starting with the mechanical occlusion cuff, passing through the pressure transducer, and on through the electrical analog filter and gain signal chain; accurately obtains the blood pressure signals to be utilized in calculating the patient blood pressure reading.

With the push of a button a patient can engage the device to perform the blood pressure testing process. Taking safety into account, pushing the same button at any time during the process will exit the testing process, deflate the cuff and turn off the device. Excessive movement by the patient will be detected and an error will be reported prompting the user to start over.

Through the use of efficient coding methods matched with carefully designed circuitry, the blood pressure tester has been able to deliver accurate blood pressure readings. The data can be wirelessly transmitted to a receiving computer which can log and transmit the data to health professionals for analysis.