Implantable wireless sensor

Abstract

The progress of a endovascular aneurysm repair can be monitored by inserting a pressure transducer sensor using a catheter into the sac during endovascular aneurysm repair and then using a small, hand-held read out device to measure pressure easily, safely, inexpensively and accurately. In one aspect a sensor is introduced into the body by the steps of loading the sensor into a catheter, and deploying into the aneurysm sac. This invention also has other applications for measuring physical properties in patients or in other sites.

Description

CROSS-REFERENCE TO RELATED APPLICATION [0001] This application is based upon co-pending, commonly assigned U.S. provisional patent application Ser. No. 60 / 503,745, filed Sep. 16, 2003, incorporated herein by reference in its entirety.FIELD OF THE INVENTION [0002] The application is directed to an implantable wireless sensor. More particularly, this invention is directed to a wireless, unpowered, micromechanical sensor that can be delivered using endovascular techniques, to measure a corporeal parameter such as pressure or temperature. BACKGROUND OF THE INVENTION [0003] Abdominal aortic aneurysms represent a dilatation and weakening of the abdominal aorta which can lead to aortic rupture and sudden death. Previously, the medical treatment of abdominal aortic aneurysms required complicated surgery with an associated high risk of injury to the patient. More recently, endografts (combining stents and grafts into a single device) have been developed that can be inserted through small inc...

AI Technical Summary

Benefits of technology

[0012] It is a yet further object of this invention to provide a micromechanical sensor with a hermetically sealed, unbreached pressure reference for enhanced stability.

[0014] The present invention comprises a device that can be implanted into the human body using non-surgical techniques to measure a corporeal parameter such as pressure, temperature, or both. Specific target locations could include the interior of an abdominal aneurysm or a chamber of the heart. This sensor is fabricated using MicroElectroMechanical Systems (MEMS) technology, which allows the creation of a device that is small, accurate, precise, durable, robust, biocompatible, radiopaque and insensitive to changes in body chemistry, biology or external pressure. This device will not require the use of wires to relay pressure information externally nor need an internal power supply to perform its function.

[0015] The MEMS approach to sensor design lends itself to the fabrication of small sensors that can be formed using biocompatible materials as substrate materials. The pressure sensor described above can be introduced into the sac of an abdominal aneurysm at the time an endograft is deployed within the aorta by using standard endovascular catheter techniques. Appropriately biocompatible coatings may be applied to the surface of the sensor to prevent adhesion of biological substances or coagulated blood to the sensor that could interfere with its proper function.

Problems solved by technology

Abdominal aortic aneurysms represent a dilatation and weakening of the abdominal aorta which can lead to aortic rupture and sudden death.

Previously, the medical treatment of abdominal aortic aneurysms required complicated surgery with an associated high risk of injury to the patient.

A significant problem with endografts is that, due to inadequate sealing of the graft with the aorta, leaks can develop that allow blood to continue to fill the aneurysmal sac.

Left undiscovered, the sac will continue to expand and potentially rupture.

These procedures are expensive, not sensitive, and painful.

In addition, they subject the patient to additional risk of injury.

While some of the above objectives are accomplished, this device has multiple problems that would make its use impractical.

For example, the sensor system disclosed in the Van Bockel patent relies on a mechanical sensing element that cannot be practically manufactured in dimensions that would allow for endovascular introduction.

In addition, this type of pressure sensor would be subject to many problems in use that would limit its accuracy, stability and reliability.

This would impact the device's ability to maintain accurate pressure reading over long periods of time.

A fundamental problem with sensors is their tendency to drift over time.

A sensor described in the Van Bockel patent would be subject to drift as a result of its failure to seal the pressure sensing circuit from the external environment.

Also, by failing to take advantage of specific approaches to electronic component fabrication, allowing for extensive miniaturization, the Van Bockel device requires a complex system for acquiring data from the sensor necessary for the physician to make an accurate determination of intra-aneurysmal pressure.

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