A differential pressure regulating device is provided for controlling in-vivo pressure in a body, and in particularly in a heart. The device may include a shunt being positioned between two or more lumens in a body, to enable fluids to flow between the lumens, and an adjustable flow regulation mechanism being configured to selectively cover an opening of the shunt, to regulate the flow of fluid through the shunt in relation to a pressure difference between the body lumens. In some embodiments a control mechanism coupled to the adjustable flow regulation mechanism may be provided, to remotely activate the adjustable flow regulation mechanism.

Device and method for controlling in-vivo pressure

The present invention is thus directed to methods and apparatus for decreasing pressure in a first portion of a vessel of the cardiac structure of a patient by implanting a shunt communicating with an area outside said first portion, whereby a volume of blood sufficient to reduce pressure in said first portion is released. Preferably, the first portion comprises the left ventricle and the pressure reduced is the end diastolic pressure, which is accomplished by having the shunt communicate with the left ventricle so a small volume of blood is released from the left ventricle to reduce the end diastolic pressure. Most preferably, the shunt selectively permits flow when a pressure differential between the left ventricle and another chamber of a heart above a threshold pressure, whereby shunting is prevented during left ventricular systole, or, alternatively, selectively permits flow when a pressure differential between the left ventricle and another chamber of a heart is between a lower threshold and a higher threshold, whereby shunting is again prevented during left ventricular systole. In certain embodiments a semi-passive check-valve is controlled and actuated by an external signal, either using a signal generated by an intra-corporeal electrical battery or an externally coupled energy source. In certain embodiments, the shunt has a pump with an input connected to the left ventricle, or other portion with excessive pressure, and an output connected to a volume of lower pressure. The preferred method of implanting the shunt to effect the present invention is by deploying a tubular element having two ends and a tissue affixation element disposed at each of said ends via a catheter, preferably, the fixation element is a shape retaining metallic material that returns to its original shape as part of the retention aspect of its function. In preferred embodiments of the apparatus, the tubular element is comprised of a biologically inert non-metallic material.

Methods and apparatus for reducing localized circulatory system pressure

A device for regulating blood pressure between a patient's left atrium and right atrium comprises an hourglass-shaped stent comprising a neck region and first and second flared end regions, the neck region disposed between the first and second end regions and configured to engage the fossa ovalis of the patient's atrial septum; and a one-way tissue valve coupled to the first flared end region and configured to shunt blood from the left atrium to the right atrium when blood pressure in the left atrium exceeds blood pressure in the right atrium. The inventive devices may reduce left atrial pressure and left ventricular end diastolic pressure, and may increase cardiac output, increase ejection fraction, relieve pulmonary congestion, and lower pulmonary artery pressure, among other benefits. The inventive devices may be used, for example, to treat subjects having heart failure, pulmonary congestion, or myocardial infarction, among other pathologies.

Devices for reducing left atrial pressure, and methods of making and using same

A medical implant including an anchor portion including a plurality of arms adapted to engage an internal tissue wall of a body from two opposite faces, wherein the anchor portion is configured such that at least one of the arms does not have an entirely overlapping arm on the other side of the wall and an opening portion adapted to define an opening for blood flow through the internal tissue wall, when the anchor portion engages the wall.

Heart anchor device

A device for regulating blood pressure in a heart chamber is provided. The device includes a shunt positionable within a septum of the heart. The shunt is designed for enabling blood flow between a left heart chamber and a right heart chamber, wherein the flow rate capacity of the device is mostly a function of pressure in the left heart chamber.

Device and method for regulating pressure in a heart chamber

A semiconductor device with a tunnel diode (23) is particularly suitable for various applications. Such a device comprises two mutually adjoining semiconductor regions (2, 3) of opposed conductivity types and having doping concentrations which are so high that breakdown between them leads to conduction by means of tunnelling. A disadvantage of the known device is that the current-voltage characteristic is not yet steep enough for some applications. In a device according to the invention, the portions (2A, 3A) of the semiconductor regions (2, 3) adjoining the junction (23) comprise a mixed crystal of silicon and germanium. It is surprisingly found that the doping concentration of both phosphorus and boron are substantially increased, given the same amount of dopants being offered as during the formation of the remainder of the regions (2, 3). The tunnelling efficiency is substantially improved as a result of this, and also because of the reduced bandgap of said portions (2A, 3A), and the device according to the invention has a much steeper current-voltage characteristic both in the forward and in the reverse direction. This opens perspectives for inter alia an attractive application where the tunnelling pn junction (23) is used as a transition between two conventional diodes, for example pn or pin diodes, which are used one stacked on the other and which can be formed in a single epitaxial growing process thanks to the invention. The portions (2A, 3A) adjoining the tunnelling junction (22) are preferably 5 to 30 nm thick and comprise between 10 and 50 at % germanium. The doping concentration may be 6×1019 or even more than 1020 at/cm3. The invention further relates to a simple method of manufacturing a device according to the invention. This is preferably done at a temperature of between 550° C. and 800° C.

Semiconductor device with a tunnel diode and method of manufacturing same

Devices with Schottky junctions are manufactured in that a semiconductor body (10) with a substrate (11) is provided with a first, for example n-type semiconductor region (1) in the form of an epitaxial layer. A Schottky metal (4) is locally provided thereon. A second semiconductor region (2) is advantageously formed directly below the Schottky metal (4), with the purpose of adjusting the level of the Schottky barrier. Around this, a third semiconductor region (3) is formed in the first region (1) at at least two sides, which third region is then of the p-conductivity type and, when it entirely surrounds the second region (2), forms a so-called guard ring (3). A disadvantage of the above known method is that the devices obtained thereby have a (forward) current-voltage characteristic which is not very well controllable and reproducible. This hampers mass manufacture. To counteract this disadvantage, a method according to the invention provides the formation of the second semiconductor region (2) by means of low-temperature gas phase epitaxy, such that it has the first or the second conductivity type, and the third region (3) is formed by means of ion implantation, the second semiconductor region (2) being formed after the third region (3) has been formed. Devices are obtained thereby whose current-voltage characteristics can be adjusted over a wide range with very good reproducibility and well controlled. The second semiconductor region (2) may be provided over the entire surface or selectively within the third region (3) only.

Method of manufacturing a semiconductor device with a schottky junction

A semiconductor device with a tunnel diode (23) is particularly suitable for various applications. Such a device comprises two mutally adjoining semiconductor regions (2, 3) of opposed conductivity types and having doping concentrations which are so high that breakdown between them leads to conduction by means of tunnelling. A disadvantage of the known device is that the current-voltage characteristic is not yet steep enough for some applications. In a device according to the invention, the portions (2A, 3A) of the semiconductor regions (2, 3) adjoining the junction (23) comprise a mixed crystal of silicon and germanium. It is surprisingly found that the doping concentration of both phosphorus and boron are substantially increased, given the same amount of dopants being offered as during the formation of the remainder of the regions (2, 3). The tunnelling efficiency is substantially improved as a result of this, and also because of the reduced bandgap of said portions (2A, 3A), and the device according to the invention has a much steeper current-voltage characteristic both in the forward and in the reverse direction. This opens perspectives for inter alia an attractive application where the tunnelling pn junction (23) is used as a transition between two conventional diodes, for example pn or pin diodes, which are used one stacked on the other and which can be formed in a single epitaxial growing process thanks to the invention. The portions (2A, 3A) adjoining the tunnelling junction (22) are preferably 5 to 30 mm thick and comprise between 10 and 50 at% germanium. The doping concentration may be 6 x 1019 or even more than 10?20 at/cm3?. The invention futher relates to a simple method of manufacturing a device according to the invention. This is preferably done at a temperature of between 550 °C and 800 °C.

Silicon germanium semiconductor device and a method of manufacturing the same

A semiconductor device with a tunnel diode comprises two mutually adjoining semiconductor regions ( 2, 3 ) of opposed conductivity types having high enough doping concentrations to provide a tunneling junction. Portions ( 2 A, 3 A) of the semiconductor regions adjoining the junction comprise a mixed crystal of silicon and germanium. The doping concentration of both phosphorus and boron are substantially increased, given the same amount of dopants being offered as during the formation of the remainder of the regions. The tunneling efficiency is substantially improved, and also because of the reduced bandgap of said portions ( 2 A, 3 A). A much steeper current-voltage characteristic both in the forward and in the reverse direction is achieved. Thus, the tunneling pn junction can be used as a transition between two conventional diodes which are stacked one on the other and formed in a single epitaxial growing process. The doping concentration may be 6×10 19 or even more than 10 20 at/cm 3 . A simple method of manufacturing such a device is preferably done at a temperature between 550° C. and 800° C.

Boer Wiebe Barteld De

Papers

Semiconductor device with a tunnel diode and method of manufacturing same

Method of manufacturing a semiconductor device with a schottky junction

Silicon germanium semiconductor device and a method of manufacturing the same

Method of manufacturing semiconductor device with a tunnel diode

Silicongermanium semiconductor device and a method of manufacturing the same