US 6,580,947 B1 · Magnetic field sensor for an implantable medical device

Abstract

An implantable medical device (IMD) uses a solid-state sensor for detecting the application of an external magnetic field, the sensor comprises one or more magnetic field responsive microelectromechanical (MEM) switch fabricated in an IC coupled to a switch signal processing circuit of the IC that periodically determines the state of each MEM. The MEM switch comprises a moveable contact suspended over a fixed contact by a suspension member such that the MEM switch contacts are either normally open or normally closed. A ferromagnetic layer is formed on the suspension member, and the suspended contact is attracted or repelled toward or away from the fixed contact. The ferromagnetic layer, the characteristics of the suspension member, and the spacing of the switch contacts may be tailored to make the switch contacts close (or open) in response to a threshold magnetic field strength and/or polarity. A plurality of such magnetically actuated MEM switches are provided to cause the IMD to change operating mode or a parameter value and to enable or effect programming and uplink telemetry functions.

Claims18

Dependent claims

An implantable medical device (IMD) to provide therapy delivery and/or monitoring for a patient, the IMD further comprising:

a control and timing circuit implementing an IMD operating mode;
a microelectromechanical switch having a fixed contact, a moveable suspension member, a ferromagnetic layer formed on the suspension member, a moveable switch contact formed on the suspension member and disposed over the fixed contact, wherein the moveable switch contact is normally in a first position and assumes a second position when a predetermined magnetic field strength is applied to the ferromagnetic layer and causes a deflection of the suspension member:
a switch processing circuit producing a switch signal responsive to the assumption of the second position by the moveable switch contact;
and
wherein the control and timing circuit implements an IMD operating mode in response to the switch signal.

2 more elements

An implantable medical device (IMD) having a hermetically sealed enclosure and adapted to be implanted in a patient's body and to provide a therapy delivery and/or monitoring, the IMD further comprising:

a control and timing circuit implementing an IMD operating mode;
a first microelectromechanical switch having a fixed contact, a moveable suspension member, a ferromagnetic layer formed on the suspension member, a first moveable switch contact formed on the suspension member and disposed over the fixed contact, wherein the first moveable switch contact is normally in a first position and assumes a second position when a predetermined magnetic field strength is applied to the ferromagnetic layer and causes a deflection of the suspension member;
a first switch processing circuit producing a first switch :signal responsive to the assumption of the second position by the moveable switch;
a second first microelectromechanical switch having a fixed contact, a second moveable suspension member, a ferromagnetic layer formed on the suspension member, a moveable switch contact formed on the suspension member and disposed over the fixed contact, wherein the second moveable switch contact is normally in a first position and assumes a second position when a predetermined magnetic field strength is applied to the ferromagnetic layer and causes a deflection of the suspension member;
a second switch processing circuit producing a second switch signal responsive to the assumption of the second position by the moveable switch;
and
wherein the control and timing circuit in response to the first switch signal implements a first IMD operating mode and in response to the second switch signal implements a second IMD operating mode.

4 more elements

Dependencies are inferred from the claim text.

Magnetic field sensor for an implantable medical device

Life of this patent

Magnetic field sensor for an implantable medical device

Life of this patent

Abstract

Claims18