In nature multiple animals have developed intriguing shooting mechanisms for food capture, defence, and reproductive reasons. Think for example on the amazing tongue shooting capability of the chameleon and the appendage strike of the mantis shrimp.
These shooting mechanisms can offer inspiration for new ideas on the technological development of fast acceleration mechanisms in medicine. High-speed shooting mechanisms can, for example, be used for the endovascular treatment of Chronic Total occlusions (CTOs). CTOs are heavily calcified and are thus difficult to puncture and cross with the small (0.36 mm) guidewire. The required force to puncture the CTO is often higher than the buckling force of the guidewire due to the low bending stiffness (EI) and long (unsupported) length (L). As a result, the guidewire often buckles. Buckling in turn causes procedural failure since the CTO cannot be crossed. Buckling of the crossing tool may be prevented by using a high-speed crossing tools as this increases the buckling resistance of the guidewire and potentially minimizes the puncture force of the CTO.
With this in mind an innovative high-speed crossing tool was developed using nature’s shooting mechanisms as inspiration. The crossing tool (OD 2 mm) incorporates an innovative spring-driven indenter and decoupling mechanism for high-speed puncturing of the proximal cap. First tests have been very promising. The prototype hit the CTO with an average speed of 3.4 m/s and was able to deliver a maximum force of 20 N (without buckling), which is well over the required 1.5 N to puncture the CTO. Additionally, the device was tested on CTO models made out of calcium and gelatine of different consistency. Puncture was achieved with on average 2.5 strikes for heavily calcified (77 wt% calcium) CTO models.
We feel that with continued development of this technique it will become possible to deliver high forces in ultra thin devices, such as guidewires, and as such increase the success rate of the the endovascular treatment of CTOs and other minimal invasive applications.
The FA3D hand is a 3D printed Hand printed with a flexible filament. The fingers of the hand have multiple joints, allowing for adaptive gripping. The fingers have elastic joints and can be printed as one part. Therefore assembly of the finger phalanxes is not necessary.
Due to its adaptive gripping, the FA3D Hand can hold a broad range of objects.
The FA3D Hand consists of 8 3D-printed parts. The parts can be connected with standard bolts and nuts. Steel cables are used to actuate the fingers.
The hand is body powered. It can be controlled by pulling the control cable, by using a shoulder strap.
Commercializing our squid-based steering technology, spin-off DEAM received an investment from the investment firm Carduso Capital in Groningen, the Netherlands. This will make it possible for DEAM to start-up the production phase, focusing on a market introduction second half of 2018.
In the television program “Het ei van Midas”, renowned Dutch biologist Midas Dekkers explores how ideas from Nature can inspire new technology. In this episode, he visited the BITE-group to learn more about our tentacle-like maneuverable instruments.
Renowned dutch biologist Midas Dekkers talks on Pauw about his new program “Het EI van Middas” that discusses nature-inspired technology, giving our octupus inspired steerable instruments as an example.
The Dutch TV-program “De Kennis van Nu” (“The Knowledge of Now”) has made a documentary about the research in the BITE-group, explaining how we use the anatomic architecture of cuttlefish tentacles as a source of inspiration for our research on maneuverable surgical devices.
Wasp ovipositors are thin and flexible needle-like structures used for laying eggs inside wood or larvae. Wasp ovipositors are composed out of longitudinal segments, called “valves”, that can be actuated individually and independently of each other with musculature located in the abdomen of the insect. In this way the wasp can steer the ovipositor along curved trajectories inside different substrates without a need for rotatory motion or axial push.
Inspired by the anatomy of wasp ovipositors, we developed an Ovipositor Needle containing a 2 mm thick “needle” composed out of four sharp and polished stainless steel rods, representing four ovipositor valves. The four valves can be individually moved forward and backward by means of electromechanical actuators mounted in a propulsion unit that is standing on four passive wheels. If the needle is inserted into a gel that represents tissue, and if the four valves are sequentially moved forward and backward, the friction behaviour around the valves in the gel will result in a net pulling motion that drives the needle forward through the gel. The ovipositor needle is therefore self-propelling, meaning that it does not need a net pushing motion for moving forward through tissue like normal needles do.
Ovipositor Needle I is part of the WASP project that focuses on the development of steerable needles for localized therapeutic drug delivery or tissue sample removal (biopsy). In a new prototype that is currently under development, we aim to extend the self-propelled needle with steering capabilities at an outer diameter of just 1 mm.
In nature, several species of parasitoid wasps have a thin and flexible needle-like structure, called ovipositor, which is used to deposit eggs in a host (e.g., a larva) hidden into tree trunks or fruits. The wasp ovipositor consists of three segments, called valves, longitudinally connected that can slide along each other. The animals can drill in different substrates by actuating the valves in a reciprocal motion and steer by changing the relative positions of the valves during probing (i.e. protracting and retracting of the valves).
We are currently developing a novel steerable needle for minimally invasive interventions inspired by the wasp-ovipositor. However, the steering mechanisms used by the animal is not yet fully understood.
The project will focus on understanding how the steering mechanism works and which characteristics of the ovipositor play a relevant role.
The student will use detailed 3D images of different ovipositors to design several replicas of the wasp ovipositor in larger scale with 3D printed techniques. The prototypes will be tested with an experimental facility where motion pattern and speed can be controlled. The ovipositors will be inserted in gelatine of different concentration to study the design parameters effecting the steering mechanism.
Comfort and functionality of upper limb prosthetics is highly dependent on socket performance. Correct anatomical fit is therefore of paramount importance for prosthetic designs. We believe that the complex design process of prosthetic sockets can be achieved automatically using accurate anatomical models of the stump. With the increasing advance in smartphone technology it is possible to reconstruct digital models based on camera information. We plan to explore current technologies for generating 3D digital models from multiple 2D photos and assess such techniques to stablish a framework in which smartphone technology can be used to generate 3D computer models of upper limb stumps. Using precise geometry of the stump and current CAD technologies it is possible to create a socket design that fits accurately into the residual limb. We plan to adopt such process to build fully working prosthetic sockets using 3d printing technology for developing countries.
Contact: Juan Cuellar, J.S.CuellarLopez@tudelft.nl
Solving medical problems through nature’s ingenuity