Site News  |   Monitor Keywords  |   Monitor Archive  |   Organizer  |   Account Info  |

Variable antenna matching network for an implantable antenna

Variable antenna matching network for an implantable antenna description/claims

This disclosure relates generally to implantable medical devices, and to implantable antennas with a variable antenna matching network for device communications.

Electronic devices can communicate wirelessly with each other, such as by using RF communication between an antenna at each such electronic device. For example, an implantable medical device (IMD) can communicate wirelessly with an external device, such as a local external programmer for the IMD or a local RF transceiver. The local external programmer may then communicate with a remote external server or other device, such as by using a wired or wireless communication or computer network. The patient and doctor would benefit from improved communication between an IMD and external device.

Matching networks can be used in wireless systems to match a transceiver's impedance to an antenna's impedance. The matching network can help provide the maximum power transfer from a source to a load, such as an antenna. The source impedance should equal the complex conjugate of the load impedance for maximum power transfer. The antenna's impedance also varies depending upon the frequency and antenna environment. The impedance in wireless systems can be fixed to a calculated value to optimize the antenna for its desired purpose, operating frequency and operating environment. The present inventors have recognized that, for an implantable medical device, the antenna impedance is not fixed, but rather varies based upon the dielectric constant of the medium surrounding the antenna. The implantable medical device can be tested in air before insertion into the body to help ensure that the entire device is operational. However, the operational medium for the implantable medical device while inside a body is quite different from the air. A fixed matching network can attempt to balance the required performance in the air versus the required performance inside a body.

Another potential issue with the use of a fixed matching network is that the designated operational frequency may be different in different parts of the world, since different governmental bodies may designate different frequencies for various jurisdictions. Thus, the matching network may have to be changed depending upon the particular market in which the implantable medical device is to be sold. This may result in manufacturing inefficiencies and stocking problems and—even if these challenges can be met—does not resolve the issue of an IMD implanted in a person who moves from one geographic jurisdiction to another jurisdiction having a different operational frequency. Thus, the present inventors have recognized that there exists a need in the art for improved matching networks, particularly with respect to the manufacture of implantable medical devices.

An implantable medical device may have an antenna for communication with external devices or other internal devices. Changes in the patient's body position, weight, composition or other factors may change the antenna efficiency and hinder communication. The disclosed circuit may automatically adjust a matching network for an implanted transceiver to dynamically maximize transmission and reception by controlling the selected value of a plurality of capacitors, inductors and resistors.

This overview is intended to provide an overview of the subject matter of the present patent application. It is not intended to provide an exclusive or exhaustive explanation of the invention. The detailed description is included to provide further information about the subject matter of the present patent application.

FIG. 1 illustrates a schematic of a variable matching network;

FIG. 2 illustrates an automatic variable matching network according to various embodiments; and

FIG. 3 illustrates an implantable biomedical device that may use a variable matching network formed according to various embodiments.

The following detailed description includes references to the accompanying drawings, which form a part of the detailed description. The drawings show, by way of illustration, specific embodiments in which the invention may be practiced. These embodiments, which are also referred to herein as “examples,” are described in enough detail to enable those skilled in the art to practice the invention. The embodiments may be combined, other embodiments may be utilized, or structural, logical and electrical changes may be made without departing from the scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims and their equivalents.

In this document, the terms “a” or “an” are used, as is common in patent documents, to include one or more than one. In this document, the term “or” is used to refer to a nonexclusive or, such that “A or B” includes “A but not B,” “B but not A,” and “A and B,” unless otherwise indicated. Furthermore, all publications, patents, and patent documents referred to in this document are incorporated by reference herein in their entirety, as though individually incorporated by reference. In the event of inconsistent usages between this document and those documents so incorporated by reference, the usage in the incorporated reference(s) should be considered supplementary to that of this document; for irreconcilable inconsistencies, the usage in this document controls.

A variable matching network may be used to provide an antenna system that operates well in the air, such as for testing purposes, as well as in a human or animal body within which it is intended to operate, without having to compromise the network design. In certain examples, the same variable impedance matching network may also be used to respond to slowly changing impedance environments, such as due to a patient's weight gain or dehydration.

• Provisional Patent
• Utility Patent

• What Is a Patent?
• What Is a Trademark or Servicemark?
• What Is a Copyright?
• Patent Laws