Surgery – Diagnostic testing – Measuring or detecting nonradioactive constituent of body...
Reexamination Certificate
2000-04-28
2003-07-15
Huson, Gregory L. (Department: 3751)
Surgery
Diagnostic testing
Measuring or detecting nonradioactive constituent of body...
C600S341000, C604S503000, C604S066000, C604S067000, C604S891100
Reexamination Certificate
active
06592519
ABSTRACT:
FIELD OF INVENTION
This invention relates to “smart” medical devices that are useful for a wide variety of patient treatments, as well as methods of manufacture for these medical devices.
BACKGROUND OF THE INVENTION
Medical devices are used for drug delivery for various substances, such as morphine, Baclofen, Cisplatin, Clindamycin, Doxorubicin, Floxuridine (FUDR), Methotrexate, Heparin, Mitoxantrone, Octreotide Vinblastine, BDNF (brain derived nerve factor) etc. For example, conventional devices are specifically used to deliver morphine to cancer patients, baclofen to patients experiencing spasticity, and Floxuridine (FUDR) to patients requiring chemotherapy (e.g., most of these are treatments already approved by the FDA).
However, conventional devices have a number of disadvantages. For example, conventional devices cannot optically measure the concentrations of the drug being delivered, nor can they optically measure or monitor the patient site to be treated or being treated to ensure that the patient receives the correct amount and concentration of the drug to be delivered or being delivered at that site. Conventional devices also do not provide for optical detection or an optical trigger signal and/or system to initiate drug delivery. Thus, conventional devices are not “smart” devices because they cannot measure biological signals and/or monitor and control the concentration and amount of drug delivery.
Further, since conventional devices do not monitor the concentration and quality of the delivered drug, they cannot provide this information to a microprocessor, and thus, the microprocessor cannot analyze or control the amount and/or concentration of the drug based on that information. Conventional devices also cannot optically monitor the mixing of various substances that yield mixtures of short shelf life within these conventional devices, and thus cannot control the mixing of substances for optimum concentration of the mixed fluid to be delivered by the device to the patient.
Conventional devices can also experience corrosion due to the physical properties of substances to be delivered by these devices and the materials of conventional device components. Many of the drugs have high or low pHs that can cause severe corrosion to the components of conventional devices.
In addition, conventional devices do not have a coating suitable for a wide range of applications and delivery of various drugs (i.e., a “universal” coating), thereby leading to increased surgery to implant devices suitable for specific drugs or a limitation in the number of drugs that could be utilized in such devices.
In addition, conventional devices do not have coatings that can be easily converted into electrodes for the monitoring of electroactive analytes (e.g., organic molecules, dissolved gases, and metal ions) as well as the sensing of bioelectric events which indicate physiological function. Most conventional devices with electrodes require the utilization of separate structures with complicated interconnects (feedthroughs) welded or bonded to a substrate via harsh high temperature processes. Thus, there is a need for simpler fabrication procedures at lower temperatures for electrodes that allow three dimensional interconnection.
Further, conventional methods of manufacture of medical devices do not provide for methods of manufacture of devices having coatings useful for a wide variety of applications. For example, conventional methods of manufacture of medical devices do not provide for manufacture of coatings having optical windows for optical sensors, or selectively doped coatings to provide for monitoring of electrochemical conditions in various locations throughout the device surface, or coatings to provide corrosion resistance.
While optical sensors have been used in implantable devices to monitor oxygen in hemoglobin, optical sensors have not been used in implantable devices to monitor and control drug delivery in medical devices. Further, the optical sensors that have been used to monitor oxygen in hemoglobin comprise sapphire windows brazed onto optical sensors. Such brazing requires high temperature manual fabrication and is not well suited for microfabrication and automated manufacture.
Catheters having optical sensors could be used on a temporary basis to measure the amount of certain substances, such as nitrous oxide, in connection with temporary drug delivery. They have been used as oximeters as described in U.S. Pat. No. 4,750,495. However, conventional medical devices which are implantable are not capable of or designed to measure a large variety of concentrations or chemical conditions via optical and electrochemical sensors, and thus cannot control treatment, such as drug delivery, to a patient.
Thus, there is a great need for medical devices that overcome the above deficiencies in conventional medical devices and the methods of manufacture thereof.
SUMMARY OF THE INVENTION
A new smart medical device and methods of manufacture thereof have now been discovered that overcomes the deficiencies of conventional devices and methods of manufacture. The medical device of the present invention comprises an outer surface and an inner surface, and a coating on at least the outer surface or inner surface of the device. This construction provides a number of benefits. More specifically, in a preferred embodiment, the device has a universal coating that increases the corrosion resistance of the device, enabling the use of drugs with different chemistries, and/or enable the device to be a smart device that can monitor and control drug delivery and/or electrical stimulation therapies.
In a further preferred embodiment, the device has a coating that permits transmittance of signals, such as optical, electrochemical, electrical or thermal signals, to a sensor and/or microprocessor in the device. In a preferred embodiment, the coating is a diamond or diamond-like coating. The signals can relate to a wide variety of measurements, such as the effect of drug delivery to a specific site within a patient, or the concentration of a drug to be delivered to a patient, or the temperature at a specific site within a patient, or the electrochemical or electrical characteristics at a specific site within a patient.
In a preferred embodiment of the device of the invention, a coating is applied to at least the outer surface or the inner surface of the medical device. In another preferred embodiment, the medical device also has at least one optical sensor and a light diode. The light diode can emit light to a substance to be monitored and the optical sensor senses the light transmittance through or reflected by the substance being measured.
In another preferred embodiment of the present invention, two light diodes can be used to improve detection by reflectance. Depending on the wavelengths one can detect oxygen or other compounds in accordance with the present invention. The optical sensor can further send information regarding the sensed light to a microprocessor in the device, which will then identify the presence and concentration of the substance, and can further control the amount of drug delivery by the device based on the measurement of the substance. The drug delivery by the device can be accomplished by an electromechanical, electrochemical, solenoid or piezoelectric pump that pumps the delivered drug from a reservoir and through an catheter to a specific site within the patient. The sensor can be designed to monitor the drug chemistry and concentration prior to delivery to the patient. This is particularly useful to provide a controlled and intelligent system to mix drugs within the device, which may be desirable because of short shelf life of the mixture. The sensor can also monitor the mixing and send signals to a controller to alter the mixing, as well as change the amount of drug delivery as desired.
In another preferred embodiment of the present invention, the device can have boron doped areas on a diamond or diamond like coating that permits the transmittance of electrical signals. Such a doped
Banner & Witcoff , Ltd.
Flynn Amanda
Huson Gregory L.
Medtronic Inc.
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