Activity sensors for implantable medical devices
AssigneePacesetter, Inc.
InventorHerman L. Renger
Life of this patent
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Abstract
An implantable medical device including a piezoelectric accelerometer activity sensor. The activity sensor includes a thin film piezoelectric cell within a frame structure. A mass imposes a load based upon acceleration to apply lateral or transverse forces which cause the generation of an electrical potential within the piezoelectric cell, which can be used by a rate control algorithm within the device to control operation of the device.
Claims13
An implantable medical device for monitoring physical activity of a patient, comprising:
- a housing assembly suitable for implantation in body tissue;
- a frame assembly mounted within said housing assembly;
- a piezoelectric film having opposing major surfaces and respective ends attached to said frame assembly so that said piezoelectric film is supported within said frame assembly;
- a pair of conductive metal coatings affixed to opposite major surfaces of said piezoelectric film;
- a pair of electrical conductors, each attached to one of said pair of conductive metal coatings;
- and
- a mass element operative with said piezoelectric film to increase stress applied to said piezoelectric film as a result of acceleration of the of the patient.
An implantable medical device for monitoring physical activity of a patient, comprising:
- a housing assembly suitable for implantation in body tissue:
- a piezoelectric film having opposite major surfaces with metallic coatings affixed thereto, said piezoelectric film having a first predetermined length, the piezoelectric film having a first end and a second end opposite the first end;
- means for supporting said piezoelectric film within said housing assembly by the first and second ends, said supporting means having a second predetermined length slightly less than said first predetermined length of said piezoelectric film so that the piezoelectric film is slightly slack;
- conductor means for interconnecting said metallic coatings and said electrical circuitry in said housing assembly;
- and
- mass means operative with said piezoelectric film for increasing stress in said piezoelectric film as a result of acceleration of the of the patient, whereby the mass causes the piezoelectric film to sag.
An implantable stimulation device, comprising:
- pulse generating means for generating stimulation pulses to the heart at a variable rate;
- activity sensing means for sensing physical activity of a patient, said activity sensing means including:
- a frame assembly mounted within said housing assembly;
- a piezoelectric film having opposing major surfaces and respective ends attached to said frame assembly so that said piezoelectric film is supported within said frame assembly;
- a pair of conductive metal coatings affixed to opposite major surfaces of said piezoelectric film;
- a pair of electrical conductors, each attached to one of said pair of conductive metal coatings;
- and
- a mass element operative with said piezoelectric film to increase stress applied to said piezoelectric film as a result of acceleration of the patient;
- processing means for determining said variable rate of stimulation pulses based on said activity sensing means;
- and
- a housing assembly, suitable for implantation in body tissue, for housing said pulse generating means, said activity sensing means and said processing means.
Dependencies are inferred from the claim text.