This microstent is just 50 micrometers (0.05 mm) wide and half a millimeter...
This microstent is just 50 micrometers (0.05 mm) wide and half a millimeter long.
Source: Carmela de Marco / ETH Zurich

4D printing the world’s smallest stent

Researchers at ETH Zurich have developed a new method for producing malleable microstructures – for instance, vascular stents that are 40 times smaller than previously possible. In the future, such stents could be used to help to widen life-threatening constrictions of the urinary tract in foetuses in the womb.

Approximately one in every thousand children develops a urethral stricture, sometimes even when they are still a foetus in the womb. In order to prevent life-threatening levels of urine from accumulating in the bladder, paediatric surgeons like Gaston De Bernardis at the Kantonsspital Aarau have to surgically remove the affected section of the urethra and sew the open ends of the tube back together again. It would be less damaging to the kidneys, however, if a stent could be inserted to widen the constriction while the foetus is still in the womb.

Stents have been used to treat blocked coronary vessels for some time now, but the urinary tract in foetuses is much narrower in comparison. It’s not possible to produce stents with such small dimensions using conventional methods, which is why De Bernardis approached the Multi-Scale Robotics Lab at ETH Zurich. The lab’s researchers have now developed a new method that enables them to produce highly detailed structures measuring less than 100 micrometres in diameter.

Indirect 4D printing can also be used to create any number of other structures....
Indirect 4D printing can also be used to create any number of other structures. De Marco and her colleagues have also used the method to produce helices made of hydrogel that is filled with magnetic nanoparticles. In a rotating magnetic field, these microstructures start to swim – like artificial bacterial flagella.
Source: Carmela de Marco / ETH Zurich

Indirect 4D printing

“We’ve printed the world’s smallest stent with features that are 40 times smaller than any produced to date,” says Carmela De Marco, lead author of the study and Marie Skłodowska-Curie fellow in Bradley Nelson’s research group. The group calls the method they’ve developed indirect 4D printing. They use heat from a laser beam to cut a three-dimensional template – a 3D negative – into a micromould layer that can be dissolved with a solvent. Next, they fill the negative with a shape-memory polymer and set the structure using UV light. In the final step, they dissolve the template in a solvent bath and the three-dimensional stent is finished.

It’s the stent’s shape-memory properties that give it its fourth dimension. Even if the material is deformed, it remembers its original shape and returns to this shape when warm. “The shape-memory polymer is suitable for treating urethral strictures. When compressed, the stent can be pushed through the affected area. Then, once in place, it returns to its original shape and widens the constricted area of the urinary tract,” De Bernardis says.

But the stents are still a long way from finding real-world application. Before human studies can be conducted to show whether they are suitable for helping children with congenital urinary tract defects, the stents must first be tested in animal models. However the initial findings are promising, “We firmly believe that our results can open the door to the development of new tools for minimally invasive surgery,” De Marco says.

Subscribe to our newsletter

Related articles

3D printed knee implant for arthritis sufferers

3D printed knee implant for arthritis sufferers

A groundbreaking new treatment that uses 3D printed implants and that could bring relief to tens of thousands of knee osteoarthritis sufferers has received approval to be trialled in UK patients.

3D printing programmable structures from the printer

3D printing programmable structures from the printer

Researchers have developed a new process for producing movable, self-adjusting materials systems with standard 3D-printers.

Printable biosensors could make surgery safer

Printable biosensors could make surgery safer

Researchers have developed fully printable biosensor made of soft bio-inks interfaces with a pig heart.

Researchers use bioprinting to create nose cartilage

Researchers use bioprinting to create nose cartilage

Researchers have used 3D bioprinting technology to create custom-shaped cartilage. They aim to make it easier for surgeons to safely restore the features of skin cancer patients living with nasal cartilage defects after surgery.

Using 4D printing to enable spinal fusion

Using 4D printing to enable spinal fusion

4D printing helps create a biomimetic microchannel scaffold made of collagen and hydroxyapatite.

3D biocomposites can repair large bone defects

3D biocomposites can repair large bone defects

Loosening hip implants can cause major damage to the bone and a simple replacement won’t suffice to carry the load during movements. Researchers have turned to bioprinting to solve this problem.

Antibiotics embedded in 3D printed implants used to regenerate damaged bone

Antibiotics embedded in 3D printed implants used to regenerate damaged bone

Researchers have fabricated 3D scaffold implants containing antibiotics at high temperatures. These scaffolds support bone regeneration and manage the bone infections.

Advanced tech enables simulated sinus surgery

Advanced tech enables simulated sinus surgery

The world’s first international online training session utilizing advanced 3D sinus models and a telemedicine system has taken place.

A novel ink to 3D print bone with living cells

A novel ink to 3D print bone with living cells

3D printers may one day become a permanent fixture of the operating theatre after scientists showed they could print bone-like structures containing living cells.

Popular articles

Subscribe to Newsletter