# What Works - What doesn't...

A project log for Individualised nasal CPAP cannula for preterm kids

Preterm infants come in lots of different sizes. Nasal CPAP cannula come in few sizes. Read on to see if we can 3D print a solution.

Ben Hartmann 08/17/2015 at 10:110 Comments

The basic template with customisable dimensions works from a software perspective and prints (just). You may notice when the object rotates on the screen I need to write the code to cut out the internal surface of the main cylinder where the two nares tubes intersect it. Found the math - just not written the code yet.

I am currently optimising the printing. So trying different profiles and wall thicknesses for the cylinder tube. I am finding an eliptical (in profile) cylinder prints well as does a cylinder with a circular outer surface and eliptical inner surface. Bridging the top of the cylinder is obviously the difficult part of the print.

Next step will be to import a 3D facial scan into a Processing sketch as a PShape object and work out how to extract the data I need to match the basic template to the profile of the infants face. Got some ideas on how to write a loop to run through the points that define each face in the PShape and extract a plane (through y axis). Given this is the first programme I have ever written it is a little daunting.

Currently the Processing sketch draws the cylinder by drawing the circles each end of the cylinder (inner and outer) and then essentially joining them up with a series of triangular surfaces. I figure if I can get a profile of the face, directly under the nose, and then slice that line into a number of segments I can then draw a whole bunch of connecting cylinders that follow the profile of the face.

That's the plan anyways. At the very least I am pretty happy with my progress for a complete novice.

I plan that this will be the first prototype - design elements may change once the proof of concept is complete. A few interesting ideas have cropped up while printing these test versions. We do think it might be interesting to look at the internal structure of the main cylinder. Creating turbulent air flows within this form may improve ventilation. This could well be an interesting application of the rapid prototyping concept. Particularly as the glaring obvious issue this product will have is that there is currently no FDA (or TGA in Australia - where we are based) approved flexible 3D printing filament. Partly the point of this Hackaday Prize entry is to demonstrate the potential uses of such a filament.