UCL1: Novel Materials for Bio-Medical Applications

The Initial System:To Do:• Contact companies• Take

measurements• Order components• Laser cut• Solder• Design a system

set-up

The Updated System

• Longer distance to extrude along

• All components are level• Sturdy & fixed• Protected • Fancy

Thomas Sanladerer Filament Diameter Sensor

Uses a Hall sensor & magnet pairing to detect magnetic fields and convert to potential differences. This is converted to ADC input via the Arduino which can be calibrated within the sketch (right column indicates diameter in millimetres). There is some magnetic interference causing noise to effect the outputs, my next step is to develop something to cancel this out.

My First Filaments:The clear colorfabb_XT filament below indicated that there were a lot of air pockets in my filaments which could cause issues when trying to print.

The next step in my development of this system was to reduce the air pockets as far as possible & create filaments of consistent diameters.

Improving the quality of filaments

I extruded the colorfabb_XT filaments again at 200 degrees Celsius rather than 240 degrees Celsius I had used previously. This allowed for a much slower extrusion speed. This immediately resulted in a drop in the number of air pockets.

To improve the quality further I’d propose that we remove an element of the extruder that prevents the raw granules from entering the Auger screw at an even distribution. I’d also suggest a more narrow hopper to prevent granules from sitting at the sides of the entrance.

To improve consistency in filament diameter, it would be beneficial to develop a casing for the diameter sensor which reduces noise in the readings by cancelling out interfering magnetic fields.

I made a filament using 50% failed prints and 50% PLA granules. I was only able to attempt this once before the end of my internship but I saw a big potential in making filaments from recycled materials using this set-up. Issues arose from the unevendistribution of the materials, resulting in a slow extrusion, discoloration and uneven surfaces. However, with a few adjustmentsto the hopper, where materials are funnelled into the extruder, I think this could make a big impact on the waste involved with 3D printing plastics.

My Recycled Filament

Public Engagement• Teaching Year 8 boys about

Ultrasound• Teaching Year 2 children about 3D

printing & organs in the body

• Speaking with school-children enabled us to question what they thought it meant to be a scientist.

Q: What is a scientist?A: Curious, respectful, resilient

• Breaking stereotypes allows students to view science as a possible pathway for themselves; rather than a job done by adult men in lab coats.

Attending workshops & workplace events:• Frugal innovation workshop with

Dr Prashant Jha• WEISS away day• UCH nurses training

Workshop: learnt about how medical issues can be solved at low costs to increase accessibility & pitched our own solutions to common issues. Also learnt about the opportunity to work for Dr Prashant Jha as an intern in San Francisco.

Away day: observed the achievements of WEISS in the past year & spoke to members about their own journeys. This gave me some ideas what I would like to do after graduating.

Training: learnt about PCNL kidney stone removal & the tools/technology uses to do so.

Kidney Phantom for PA Imaging

(left) First model printed, over-extruded and too much carbon black dye in healthy material. (right) The completed half shell kidney print using the WelGax printer. The second model was good and we were able to scan it and confirm the mixture for the healthy & unhealthy tissue were suitable for PA imaging.However, the model was under-extruded so we printed again to create a whole model without gaps for the internal structure.We planned to then print another model with the internal structure made from a material with contrast somewhere between the healthy & unhealthy tissue.

Below is the set-up used to mix the material used to print the phantom. We used gel wax, glass microspheres, titanium oxide and optional dye. We used a hand mixer, a sonicator and a de-gas chamber to mix on a particle level and remove air pockets.

First Photoacoustic Image Second Photoacoustic Image

We used glass microspheres, titanium oxide & carbon black dye for the unhealthy tissue in both models (red shapes in both images). The first scan showed that our healthy tissue was too attenuating and we needed to change the material composition.

The healthy tissue composition was the same as the unhealthy but had much less carbon black dye. When making the second model we didn’t use dye and the results were much better. We were told to fill the internal structure with a material in-between the healthy and unhealthy tissue to give a contrast & detail in the scan.

Third Kidney ModelWe improved the extrusion rate by increasing the heat bath. This reduced the air holes in the model making it much more suitable for photoacoustic imaging.

We filled the internal structure with a material in-between the healthy & unhealthy tissue; adding some unhealthy tissue into a pocket.

The final imaging session we did showed a nice contract between the external and internal structure. However, the unhealthy tissue blended too much with the internal structure and we were advised to make the tissue using much more dye. This is something we will pass on to those continuing with the project.

A big thank you to Ogden Trust, Daniil, Guy & Karol for making my 8 week internship at UCL not only possible but also unforgettable in the best of ways!

The people I’ve met & the tasks I’ve been set have inspired me even more to pursue a career in medical physics & research.