Blood pressure monitoring system and method of having an extended optical range

A sleeve comprising:

• fabric which has a light transmission property and a light reflection property that undergo measurable change when the fabric stretches;
• a radiation source mounted to the fabric;
• and
• a radiation detector mounted to the fabric.

A method for monitoring blood pressure of a wearer comprising the steps of:

• inflating an inflatable cuff disposed over a portion of the body of a wearer to differing air pressures thereby to modify the flow of blood through an artery located in the portion of the body of a wearer over which the cuff is disposed;
• disposing on, over or in the inflatable cuff a patch at least a portion of which is formed from a fabric which has both a light transmission property and a light reflection property when the fabric is illuminated with light in the range from about 400 to about 2200 nanometers, the amount of light transmitted through the fabric relative to the light reflected by the fabric being able to change when the fabric stretches in response to motion in the body of a wearer due to changes in the flow of blood through an artery disposed beneath the patch;
• using a radiation source mounted in or to the patch, said radiation source illuminating the patch with radiation in the range from about 400 to about 2200 nanometers;
• using a radiation detector mounted in or to the patch, said radiation detector responsive to incident radiation in the range from about 400 to about 2200 nanometers to produce a signal representative thereof, the source and detector being in relative positions such that the reception of incident radiation by the detector is directly affected by a change in the amount of light transmitted through the fabric relative to the light reflected by the fabric as the fabric stretches in response to motion in the body of a wearer due to changes in the flow of blood through an artery disposed beneath the patch occurring in consonance with variations in the air pressure within the inflatable cuff;
• and
• recording the pressure in the cuff in response to the signal output from the detector when the output of the detector is at a minimum value and the pressure in the cuff following the minimum when the signal from the detector again lies within a predetermined range of a baseline signal value.