Surgery: light – thermal – and electrical application – Light – thermal – and electrical application – Light application
Reexamination Certificate
1999-03-02
2001-08-14
Gibson, Roy (Department: 3739)
Surgery: light, thermal, and electrical application
Light, thermal, and electrical application
Light application
C607S092000, C606S014000
Reexamination Certificate
active
06273904
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to an apparatus and a method for providing medical therapy at an internal treatment site within a patient's body, and more specifically, to an apparatus and a method for energizing a light source to provide the therapy at the internal treatment site, using a flexible polymer battery.
BACKGROUND OF THE INVENTION
In the 1970s, researchers discovered that polymer-salt complexes could serve as excellent electrolytes for solid state battery cells. In such a cell, the polymer is the electrolytic medium through which lithium cations are carried from a metallic lithium anode to a cathode composed of an intercalating material, such as titanium disulfide. The presence of a potential difference between the anode and the cathode of the polymeric cell produces an electric current through a load that is connected to the battery. There are several benefits associated with the use of a polymeric material as an electrolytic medium. Specifically, a polymer of this type is typically a non-volatile, non-corrosive, solid, and flexible material that may be easily processed into thin films and/or intricate shapes.
Almost since the discovery of polymer batteries, scientists have been conducting research into their possible uses. The minimal toxicity, lightweight, flexibility, and excellent energy storage capacity of polymer batteries has spurred development of their use in medical applications. One such application has been to provide electrical power to energize implanted pacemakers and defibrillators. There is much less concern about the toxicity of polymer batteries for such uses than more conventional Ni-Cd, or metallic hydride rechargeable batteries. Furthermore, polymer batteries can be fabricated with a minimal amount of metal, which avoids undesirable imaging artifacts that are often caused by implanted metal objects within a patient's body. Since polymer batteries are flexible, they can be distorted without damage, for example, to facilitate their insertion into a patient's body through a small incision.
Other medical applications for polymer battery power sources are likely to be developed. A prospective application of this technology that apparently has not yet been considered is providing power to energize implanted light sources to render light therapy. One type of light therapy, which is referred to as photodynamic therapy (PDT), is carried out after a photoreactive agent is administered to a patient. The photoreactive agent is preferentially absorbed by abnormal tissue at a treatment site, e.g., a tumor, rather than normal tissue. Light from a laser or other light source is administered to the treatment site to destroy the abnormal tissue. It is believed that the light absorbed by the sensitized abnormal cells that have absorbed the photoreactive agent produces singlet oxygen, which destroys the tumor cells.
Commonly assigned U.S. Pat. No. 5,445,608 discloses various embodiments for implanted probes that emit relatively low intensity light to administer PDT, and commonly assigned U.S. Pat. No. 5,800,478 discloses several embodiments for implantable flexible circuits on which light sources for administering PDT are mounted. The specification and drawings of both U.S. Pat. Nos. 5,445,608 and 5,800,478 are hereby specifically incorporated herein by reference. As disclosed in these two patents, the electrical current required to energize the LEDs or other light sources on the implanted probes can be provided from an external source coupled electromagnetically to an implanted receiver coil, or can be provided by a conventional storage battery that is implanted with the probe. Using a storage battery as a source of the electrical current energizing an implanted light probe or other medical device is preferable to providing the power at a fixed location to permit a patient to be mobile. Also, it may be preferable to employ a rechargeable battery if the PDT will likely continue for a very long period of time, to enable the therapy to continue without requiring further invasive procedures. However, conventional storage batteries represent a potential toxicity risk, are relatively heavy, and include metallic components that are undesirable when it is necessary to produce images of the patient's body using magnetic resonance imaging (MRI), or other imaging paradigms.
Accordingly, it would be desirable to energize light emitting sources (and other implanted medical devices) with polymer batteries to benefit from the lightweight, minimal metal content, and low risk of toxicity characteristics of such batteries. Moreover, polymer batteries can provide other functions and benefits not achievable with conventional batteries. For example, a flexible polymer battery can serve the purpose of a battery and its electrodes can serve as conductors extending between an implanted electromagnetic receiver and a medical device. A polymer battery can provide support for light sources or other electronic devices mounted in spaced-apart array on conductive traces applied to a flexible sheet. Further, a flexible polymer battery should provide heat sink capabilities, dissipating heat produced by light sources and other electronic devices. Because of the low toxicity of polymer batteries, they are ideal for inclusion in implanted capsules or beads designed to provide medical therapy, which may remain in a patient's body for an extended period of time.
SUMMARY OF THE INVENTION
In accord with the present invention, apparatus is defined for providing a medical therapy at a treatment site inside a patient's body. The apparatus includes a medical device that administers the medical therapy when energized by an electrical current. A polymer battery is coupled to the medical device to supply the electrical current. The polymer battery includes flexible electrodes and a polymer electrolyte that enables the polymer battery to be readily formed in at least one of three configurations. In a first configuration, the polymer battery is elongate and attached at one end to the medical device; in the second configuration, the polymer battery comprises a support for the medical device, serving as either a housing or a substrate. In different embodiments, the polymer battery is used either internally or externally of a patient's body. Finally, in the third configuration, the polymer battery and the medical device together comprise a bead or capsule. An envelope is provided for hermetically enclosing the polymer battery in the first configuration, and for hermetically enclosing both the polymer battery and the medical device in the second and third configurations. The envelope prevents fluids within the patient's body from interacting with the polymer battery.
Optionally, the apparatus may also include a current regulator and/or a voltage regulator to regulate either current or voltage supplied to the medical device. A switch may be included within the apparatus to control the electrical current flowing from the polymer battery to the medical device. The switch can be activated by either a pressure, a light signal, a radio signal, or a magnetic field.
The polymer battery is preferably adapted to connect to a source of a charging current disposed within the patient's body, so that the polymer battery can be recharged.
Electrical conductors are coupled between an anode of the polymer battery and the medical device and between a cathode of the polymer battery and the medical device. In a preferred application of this invention, the medical device comprises a light source for administering a light therapy to the treatment site.
In one embodiment, the envelope is substantially bead shaped and hermetically encloses both the polymer battery and the medical device, adapting them to be injected, ingested, or otherwise inserted into a patient's body. In another embodiment, the envelope is substantially capsule shaped, but also hermetically encloses both the polymer battery and the medical device, adapting the device for oral ingestion
Brown David J.
Chen James C.
Huston Darrin
McQuade Charles M.
Wilkerson Brian D.
Anderson Ronald M.
Gibson Roy
Light Sciences Corporation
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