Patent ID: 12194287

DETAILED DESCRIPTION

FIG.1shows a human heart10and the surrounding lungs20, wherein an intravascular blood pump100is inserted in the left ventricle11. Pumping the blood pump100supports the pumping function of the heart10by moving oxygen-rich blood coming into the left ventricle11from the pulmonary vein12into the aorta13. The intravascular blood pump can be designed for continuous pumping, for example, or the pump is based on a pulsatile system, for example, in which the pump speed is modulated.

FIG.2schematically shows the components of an intravascular blood pump100that is equipped according to the invention with a surface coating structure for the formation of electrical conductor tracks. The blood pump100comprises a tip110, wherein one or more electronic components112, in particular sensors, can be provided in a region within the tip110. The tip is closed by a slidable cap111. A first region120(inlet cage) with blood through-openings121adjoins the tip110. Blood can be drawn into the blood pump, for example from the left ventricle, through the blood through-openings121. This is adjoined by a flow cannula130and a second region140(impeller cage) having further blood through-openings141. This is adjoined by region150for a motor-operated pump device. Inside the region140there is a rotor (impeller), for example, that is operated via the pump device150, so that the pumped blood can exit through the blood through-openings141. The pump device150is adjoined by a back end160, via which the electrical connection is made. A supply cable170is provided for electrical supply and control. The motor-operated pump device is preferably a rotary pump (flow machine), wherein a reversal of the conveying direction can also be provided if necessary.

The surface coating structure according to the invention allows sensors or sensor regions, for example breakage sensors or strain sensors or temperature sensors, to be realized, in particular in the region of the flow cannula. The surface coating structures can also be used to electrically connect any existing electronic components112of the tip110to the supply cable170. This allows the length of the flow cannula130in particular, but also the regions120and140and the region with the motor-operated pump device150, to be bridged. Different components can be combined and realized as one structural element. For example, the first region120can be combined with the flow cannula130to one structural element, which can then very advantageously be equipped with the surface coating structure according to the invention for the formation of conductor tracks.

FIG.3shows a combined configuration of the first region with blood through-openings221, which is directly adjoined by the flow cannula230. The flow cannula230is advantageously realized as a flexible inlet hose or as a flexible hose guide. In this example, the flexible flow cannula230is realized by a spiral-shaped structure formed by circumferential windowed webs300. A laser-structured tube made of NiTiNoI material, for example, can be provided as the coatable material for this purpose. On the right side of the laser structured tube there is an elongated opening, which is provided for the passage of a guide wire in a per se known manner during the implantation process. The skeleton or web structures300of the NiTiNoI material are electrically functionalized by surface coating for the formation of the conductor tracks, whereby the conductor tracks can in particular be used for electrically connecting electronic components and/or for the formation of sensors. The spiral structure of the NiTiNoI tube can be produced by laser structuring. The exposed windows of the laser structured form can be closed by flexible materials, for example by silicone or polyurethane. The flexibility of the hose guide can also be achieved with other structures, for example by zigzag or wave patterns. The surface coating structure as such can be applied according to the method already described above. In this context, reference is also made to an article by Bechtold et al. (Biomed Microdevices, 2016 December; 18(6): 106) and an article by Lima de Miranda et al. (Rev. Sci. Instrum., 2009 January; 80(1): 015103), whereby these articles deal with surface structuring in general. Bechtold et al. describe the coating of thin films made of a nickel-titanium alloy to form insulated electrodes on the outer surface. Lima de Miranda et al. describe a rotational UV lithography for cylindrical geometries. The laser structuring of the NiTiNoI tube to form the spiral structure, for example, can take place before or after the electrical functionalization.

FIG.4shows a detail view of the resulting exemplary conductor track structures on the flow cannula230. The webs300of the laser-structured spiral structure (seeFIG.3), which to a certain extent form the framework of the flexible flow cannula230, leave windows301open. The windows301are preferably closed in a flexible manner, for example using silicone or polyurethane. The webs300together with the closed windows301form the hose guide of the flow cannula230. According to the invention, electrical conductor track structures302,303are applied to the webs300using lithography and coating technologies.

For the actual production of the electrical conductor tracks, a lithography mask comprising the corresponding coating structures (electrical conductor track structures) is applied for each layer. The lithography mask can be a chrome-coated quartz substrate, for example. Non-conductors such as photoresist or polyimide can be applied over a large area by dipping, for example. Non-conductors such as parylene C can be deposited in a vacuum, for example. Initial metallic layers are in particular applied by sputtering, thicker layers by electrodeposition.

There are two main approaches that can be used in the production process: According to Method 1, the tube material (for example NiTiNoI) is first provided with the electrical surface coating for the formation of the conductor tracks. In the next step, the flexible structure is produced, for example, by laser cutting (laser structuring), whereby the coating structure and the laser cutting contour are geometrically aligned to one another. In the last step, the windows of the flexible structure are closed, for example by dipping or overmolding. According to Method 2, the pipe material is structured first. The surface functionalization for the formation of the conductor tracks is then produced using the lithographic processes. Lastly, the windows of the flexible structure are closed as in Method 1. Method 1 has the advantage that the lithography process is simplified. Method 2 has the advantage that shape embossments in the NiTiNoI material are possible directly after the structuring of the pipe material; for example to “save” bends or cross-sectional changes to the cross-section of the starting material (e.g. widenings of the cross-section). Because of the process temperatures needed for the shape embossment, it is generally advantageous to perform this step before the lithographic surface coating.

FIG.5shows particularly preferred configurations of the conductor tracks, in which the conductor track structure is designed as a sensor (left) or as an electrical connection and additionally as a sensor (right). As inFIG.4, the flow cannula230is equipped with conductor tracks302,303, which are formed by surface structuring of the webs300of the flow cannula230(right part of the illustration). Meandering conductor tracks are provided as well, which form the sensor regions304(left) or the additional sensor region305(right). Straight sections of the conductor tracks can be provided between individual sensor regions304, or the sensor region305is formed by a continuously meandering conductor track. The input and output lines306,307of the sensor regions304can be made of a different material than the sensor regions themselves. A plurality of sensor regions can be implemented via separate input lines or even with a common return channel line308, for example.

For a temperature sensor, for example, it can be provided that the conductor tracks of the sensor regions304or305are made of platinum, because platinum has a very linear resistance-temperature relationship. The input and output tracks306,307,308expediently have the lowest possible resistance in order to have little influence on the sensor signal. The conductor track structures can also be used as strain or breakage sensors, for example. They can also be used as capacitive sensors, electrode surfaces or contact pads for further sensors, for example.

FIG.6shows a preferred electrical contacting of the conductor tracks302,303via electrical contact pads310,311,312,313. This electrical contacting can take place, for example, at the end of the flow cannula230, i.e. in the direction toward the second region140. However, it is also possible for the conductor tracks to also be guided over other components of the blood pump, for example over the region140,150to the electrical connection region160. The electrical connection can be established by conductive gluing, soldering, bonding or frictional connection, for example. The connection can be made directly from NiTiNoI component to NiTiNoI component, for example, or from NiTiNoI component directly to a cable or a thin-film substrate, depending on the configuration of the blood pump.

FIG.7shows a cross-section through the resulting layer structure that realizes the electrical conductor tracks.710represents the underlying NiTiNoI structure or another coatable material as the support structure of the flow cannula.720represents an insulating base layer, for example made of silicon oxide or polyimide.730shows the metallic conductor track structures, for example made of gold.740represents an insulating cover layer, for example made of silicon oxide, polyimide or parylene. A multilayer structure, for example a two-layer structure as illustrated inFIG.8, can be created by repeating the surface coating several times (surface lithography).710,720,730and740represent the coatable structure, the insulating base layer, the first layer of the conductor track structures or the insulating cover layer, as inFIG.7. A further conductor track750disposed at a slightly higher level is additionally provided in the spaces between the conductor track structures730. During production, the space (empty space) between the conductor track structures730on the lower layer is used for the metallization of the upper layer by disposing the metallic conductor layer in this space. This offset arrangement of the conductor tracks on different levels prevents the formation of larger protrusions or roughnesses of the surface structure in the regions in which metallic conductor tracks would be on top of one another. This can occur in particular in higher multilayer structures having six or more layers. In this respect, this embodiment with an offset arrangement has the advantage over a purely coaxial embodiment that the resulting layer thickness of the conductor structure as a whole is reduced. This embodiment is also particularly advantageous compared to a coplanar design, because the overall conductor width is reduced. If an offset arrangement of the conductor tracks is not desired or possible, it is alternatively also possible to compensate any unevenness that may occur due to superimposed conductor tracks, for example with a silicone layer or the like.

FIG.9shows a further structure of a multilayered conductor track structure. Four narrow conductor tracks910and two wide conductor tracks920are disposed one above the other on the coatable material (not shown in detail). The narrow conductor tracks910serve as a communication bus for a pressure sensor and a temperature sensor in the tip of the blood pump, for example. The wide conductor tracks920have a lower resistance (electrical power) and are used, for example, to connect an ultrasonic element in the tip of the blood pump. To produce such a structure, a total of seven layers are required for the surface coating.FIG.10shows a similar example of a 5 multilayered structure having four narrow conductor tracks1010and two wide conductor tracks1020. Metallizations, which shield the conductor tracks1010and1020against one another and to the outside, are additionally provided as a shielding1030, so that a defined line impedance and less high-frequency radiation are achieved along with a shielded routing of the signals. A total of 11 layers are required to produce such a structure. In the contact pad region, the up to 11 layers can expediently be widened accordingly and, for example, passed into the top metal layer through a vertical through-connection.