Reusable inductive transducer for measuring respiration

The present invention is an inductance plethysmograph transducer particularly suited for use in respiratory monitoring. The transducer is in the form of a woven fabric providing a substantially flat extensible belt for encircling a portion of a patient for a wide range of patient sizes. The transducer is used for monitoring changes in cross-sectional area corresponding to changes in volume of an expandable organ such as the patient's chest or abdomen. At least one electrical conductor is woven directly into the fabric in a manner that improves the electrical performance of the transducer over the prior art in two ways. First, a high-density weave is used for the fabric that produces many more inductive turns of the embedded conductor(s), thereby increasing the overall inductance change, hence improving the signal to noise ratio, and increasing the expandability of the effective length of the transducer. Secondly, the conductor(s) are oriented within the weave perpendicular to the surface or the torso of a patient being monitored, thus reducing artifact due to body capacitance. In addition to improvements in the electrical performance, the manufacture of the inductance sensor is a single step process that can be carried out on existing looms, reducing the overall cost while improving the flexibility, durability, and ease of use. The present invention is also machine washable making reuse much less labor intensive and therefor much less expensive.