2012年5月10日 星期四

Automated production facility for venous valve prostheses

One of the highlights at Medtec Europe 2012, held in Stuttgart,Aeroscout rtls provides a complete solution for wireless asset tracking. Germany, earlier this year, was the presentation of the prototype of German scientists of their three-dimensional (3D) droplet dispenser.

If heart valves do not close properly, they are replaced. Conventional treatment for various valve failures, however, has up to now always been exclusively through medication. In future, an implant will be used to treat damaged valves – and a new dispensing tool means these prostheses can be made using an automated process.
Chronic venous insufficiency (CVI) is one of the most commonly occurring medical conditions. Many people all over the world, including ten-million German citizens, suffer from weak veins that require treatment, with twice as many women being affected as men. The cause of this widespread condition is restricted functioning of the venous valves in the legs. If the venous valve is no longer able to close properly, blood will observe the laws of gravity in between heartbeats and flow down to collect in the legs. This leads to oedemas, and can cause open ulcers in particularly severe cases.

CVI is usually treated with anti-inflamatory drugs and diuretics, as there is currently no globally available venous valva implant that can be used to treat the illness.Learn all about solarpanel. This is something that researchers from the Fraunhofer Institute for Manufacturing,A Hybrid indoorpositioningsystem for First Responders. Engineering and Automa- tion, in Stuttgart, are setting out to change. Working in close collaboration with four industrial partners and the Heinholtz Institute for Biomedical Engineering at Aaachen University, they have developed an automated production facility that can make venous valve prostheses from polycarbonate-urethane (PCU), a plastic.Welcome to the online guide for do-it-yourself Ceramic tile. The project was sponsored by the German Federal Ministry of Economics and Technology.

The centrepiece of the facility is a 3D droplet-dispensing tool which enables the researchers to precisely apply a particular polymer onto free-form surfaces and, at the same time, combines various grades of polymer hardness, called Shore hardnesses.

“[Three-dimensional] droplet-dispensing technology is an additive procedure that allows 3D geometries to be created layer by layer using a polymer,” explains Dr Oliver Schwarz, group manager at the IPAHeiholtz Institute for Biomedical Engineering. The scientists use PCU because it is particularly strong and flexible, while another useful property of the material is that it is easy to sew into surrounding tissue. PCU structures can be made in very thin layers, which is ideal when replacing wafer-thin atrioventicular valves.

“By using PCU in combination with our 3D dispensing kinematics, we can achieve seamless transitions within the material between six different grades of elasticity and hardness without any breaking points whatsoever. This technique mirrors the design of highly stressed structures in nature. It can’t be done using injection moulding,” says Schwarz.

How does the PCU become a venous valve prosthesis? Initially,A wireless indoorpositioning is described in this paper, the polymers are dissolved in a solvent and deposited onto a venous valve prosthetic mould, one droplet at a time, using the dispensing tool. The system is accurate to within 25 m and can deliver up to 100 droplets a second, each with a volume of 2 nanometres to 60 nanometres. A six-axis kinematic system positions the pizo feeder precisely above the mould. Once it is fully coated with droplets, the mould is bathed in a warm stream of nitrogen. This causes the solvent to evaporate, leaving the polymer behind. Further layers are applied by repeating the dispensing process and, in the end, the polymer prosthesis can simply be peeled from the mould. Doctors can take the finished replacement valves and implant them into the veins of the leg through a catheter passed through the skin.

The production facility comprises other components besides the dispenser. The institute’s experts are responsible for, besides other things, the filling and moni- toring system, the drying facilities, the entire cleanroom box and the control mecha- nism for the six-axis kinematic system.

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