The MDMouse hardware consists of the following elements:

• A commercially available optical mouse
• An electronic sphygmomanometer

The electronic sphygmomanometer consists of a pressure cuff assembly that has the following components:

• Inflatable air bag
• A solenoid
• An extender arm
• A motorized air pump
• A pressure sensor
• A release valve

The solenoid and the extender arm are used to extend the cuff assembly out of the mouse housing so it can be used for taking blood pressure.  The air pump provides the pressurized air to selectively expand the air bag so that it grasps the user's finger when it is inserted into the finger cuff.  The pressure sensor senses the pressure at the interface between the air bag and the finger surface.  The release valve is used to release air from the air bag at a rate that is related to how the pressure sensor oscillometrically senses the systolic and diastolic blood pressure at the finger.

The blood pressure monitoring components that are situated in the mouse housing receive commands from the application software such as “start monitoring” to begin each testing session and that software also receives back the readings taken by the sensors in the mouse. That data communication is done through a MCA and USB to the UART bridge using the PC’s USB port.

The actual taking of an individual’s blood pressure using the MDMouse device proceeds as follows:

The pressure of the cuff against the finger inserted into the cuff opening is initially increased until arterial vessel pulsation is beyond cutoff (total occlusion or shutdown of the artery). The cuff pressure is then slowly decreased until the first detection of arterial vessel pulsation occurs (the first pumping of the heart also commonly known as Korotkoff Phase I).  The corresponding cuff pressure at this point will be substantially equal to systolic blood pressure which is the pressure when the heart is pumping.

As cuff pressure continues to be decreased, arterial vessel pulsations will eventually become undetectable through the cuff because of the lack of adequate cuff pressure to sense those pulsations (commonly known as Korotkoff Phase V). The pressure of the cuff at this point will be substantially equal to diastolic blood pressure – the pressure when the heart is at rest.  The frequency of pulsations sensed between the systolic and diastolic pressures is measured and is substantially equal to the heartbeat rate or pulse rate of the individual.  These two cuff pressures and the pulsation frequency are measured  and captured by the MDMouse application software.

The application software installed on the user’s PC then utilizes the digital data to create a display of the individual's blood pressure readings and pulse rate.  The software also provides additional functions including recording the data and graphically plotting data over a number of parameters such as three day averages. Communication of the data is also handled by the application software, including sending emails to medical personnel or archiving data.

The MDMouse System Approach

CalHealth has gone beyond the standard use of the oscillometric process by designing a system that uses a PC rather than a micro-chip, as is the case with other blood pressure monitors. Because the end-result of blood pressure monitoring using the oscillometric process is a collection of data points, the more data that can be generated, the better the result.  By using the PC’s significantly greater compute power, CalHealth can generate many thousands of data points instead of the many hundreds that the typical BP monitor works with.