Rapid Formation and Testing of Self-expanding NiTi Frames with a Small Form Factor Suitable for Minimally Invasive Implants

Prototyping medical implants with self-expanding nitinol frames involves time consuming design and fabrication processes before testing. Innovative technologies can reduce this timeline, enabling faster prototype design, fabrication, and testing. Traditional technologies work best for mass production.

However, cost-effective techniques are needed for rapid iteration of various prototypes, especially those made from nitinol in the initial phase of implant development. This protocol allows for fast iteration of nitinol frames and testing them for transcatheter delivery. It also allows the assessment of whether a frame or stent meets the minimum requirements for self-expansion.

That is specifically demonstrated in designing frames for an implant to be anchored on the atrial septum using 12 French characters. Our research lab develops proof of concept implantable pressure sensors for remote monitoring of patients'biomarkers with heart failure. We are interested in innovative designs that do not use electronics.

We also leverage advanced manufacturing technologies and artificial intelligence in engineering novel proof of concept implants. To begin, select a nickel-titanium wire and a copper tube. Turn on the stereoscope and manipulate the nickel-titanium wire and copper tube shown on the monitor while visually inspecting them.

Align the wire inside the tube and push it fully into the tube. To prepare 3D printed fixtures, download the STL file for the fixture or template. If any adjustments are needed, download the SDLRD file from the same repository.

Make design adjustments in proprietary CAD software and export it as STL file. Then open the slicing software and import the STL file. Select the object to be 3D printed and click on the pane of slice.

Save the file as a G-code file and save it on a micro SD card. After that, pull out the micro SD card. Now, turn on the FDM 3D printer and insert the micro SD card.

From the screen, select Prepare, then Preheat and choose PLA. Then select Back and print. Choose the G-code file and tap Print.

Wait for the machine to 3D print the part. After the completion of the 3D printing, remove the printed part, and using pliers, cut any support structures. Then file the part where there are coarse edges.

And with a marker, mark the areas to be drilled. Using a hand drill, drill holes in the 3D printed geometry. Pass screws through the holes of the 3D printed part using a screwdriver.

Now hold the nickel-titanium and copper frame and pass it through the central hole. Using tweezers or pliers, fold or bend the copper tube around all the screws to form the desired shape. Then unscrew the screws.

Using a soldering gun, heat the 3D printed fixture to soften it. After that, employ tweezers or pliers to remove the unwanted parts. Then turn on the furnace tube and monitor the temperature using a Thermocable.

When the temperature reaches 500 degrees Celsius, place the copper and nickel-titanium frame in the furnace for three minutes. Afterward, using a hook, take out the nickel-titanium and copper frame and quench it in distilled water. To etch the copper, submerge the nickel-titanium and copper frames in the ammonium persulfate solution for approximate eight hours.

Once the copper is fully etched, use tweezers to remove the frame and triple rinse the released nickel-titanium frame in distilled water. Then turn on the microscope and place the nickel-titanium wire under it to check for any undesirable curvature or dimensions. Begin by designing and printing a nickel-titanium frame for minimally invasive implants.

To cover the sides of the frame With thermoplastic films, open the heat press and laminate the polyurethane elastomer film on the spacer using a fluoropolymer film to avoid polyurethane adhering to the spacer. Place the nickel-titanium wire or frame around the spacer and on top of the film. Then laminate a second polyurethane film and another layer of fluoropolymer film.

Set the temperature to 240 degrees Fahrenheit. After that, close the top of the press, lock it and wait for 60 seconds. Finally, cut the extra parts of the bonded film with scissors.

To begin, design a nickel-titanium frame and cover the sides with hemocompatible elastomer. Hold a French 12 catheter by hand and pass it through a dilator and a needle. Next, secure a silicone piece on the holder.

Using the needle and dilator, create a hole in the silicone piece. Then gradually pass the catheter through the hole and retract the dilator and needle. Fold the nickel-titanium frame and push it through the proximal end of the catheter.

Using the polytetrafluoroethylene rod, push the frame toward the distal end of the catheter, then dislodge the first side of the frame. Now retract the catheter and dislodge the second side of the nickel-titanium frame on the other side of the silicone rubber. Then examine the frame under the microscope to check for any type of failure or undesired deformation.