AP projects 2015
Posted in October 2015
We got 4 weeks’ time to create a 3D printer capable of printing artificial meat in shape and texture resembling a chicken breast. A very short time for a pretty hard task. Using our time efficiently however, we managed to get a lot done in just these 4 weeks. The main reason for this is that we had clear goals that could realistically be reached within the time limit.
- Find a recipe that is extrudable in a most optimal way
- Find the best way to solidify each layer
- Create a printerhead that is able to extrude the recipe
- Scan a chicken breast to create a 3D model
- Print a chicken breast
The goals were reached in the order listed above right in time for the Science Exposition on the 27th of October. We accomplished what we did due to a lot of things that went better than we expected.
A smooth ride
Scanning the chicken breast went very well by using the easiest of methods. Combining pictures from lots of angles gave us a high quality realistic 3D model. The printing of the chicken went better than any of us had expected. The recipe allowed itself to be extruded in very narrow lines. This made it possible for us to really create a macro fibrous structure inside the 3D printed product. The final prints also turned out better than we had hoped. The touch and feeling very much resembled real meat and even the color was somewhere close to what it should be. Also flavor wise we made some first good steps. Some people really enjoyed tasting the pieces of 3D printed “chicken”. Of course every good project has some bumps in the road.
We have had a hard time getting a smooth and constant extrusion. We think this is due to inconsistency of the recipe. Now and then the nozzle gets clogged or the extruded line varies in thickness. The recipe needs more attention in the future to overcome this problem. A possible solution would be to use a different way of mixing, or lengthen the mixing time. Another obstacle was flavor. We tried using some chicken aroma’s that we got from a vegetarian snackbar. This did not add the flavor we we’re hoping for. We also tried using chicken spices from a local groceries store and this did give it some resembling flavor. However, the spices only affect the outer layer of the treated product. Overcoming these obstacles is only one of the many things that can be done in the future.
Because we mainly focused on getting a resembling texture and shape we did not have time to get in depth on flavor, which of course is a very important part for resembling real meat. That is why a lot more research should be done on getting a resembling flavor. A possible way to get a better flavor is by adding it in the recipe before printing. This way every part of the printed “meat” will taste the same. Further opportunities are: Optimizing the printer head (a needle at the moment), creating a more solid extruder, experiment with the salt solution to get it perfect and finding the exact amount of salt solution that should be sprayed onto each layer. The 3D printer could also be greatly improved by adding an autonomous spraying actuator, ensuring a higher precision because of less human interference.
3D printed meat has several market possibilities. The fiber structure which can be created by 3d printing has no resemblance in the current market. Using this technique the macro structure of the meat replacer could become much better. First of all it has low investment costs and a lots of opportunities. The 3D printing could be done at home at people by themselves, but also in mass production at a factory. A possibility would be to attach several printing heads onto one 3D printer. This way much more could be printed in the same time using one printer
All in all our eyes have been opened to the possibilities of meat replacers and the ability to print them. Because of the good collaboration of each team member we were able to accomplish more than any of us had thought possible.
After several weeks of research, testing and experimenting the we were ready to demonstrate the world’s first 3d printed chicken breast! We started the day with making the recipe for the prints. At the start of the day we also tested several taste samples which were flavored with spices. We decided the chicken pikant flavor was the most favorable and therefore we used these spices for the tasting at the science fair. After making the recipe we directly started printing in order to be able to show more samples to interested visitors
Next we brought our presentation material to the science fair. We thought we could cook the chicken on the science fair so people could see us prepare the spiced chicken. But its seemed that this was not possible due to safety reasons so we had to this at home. We succeeded with this just in time before the science fair started. Then finally the science fair started and slowly people were entering the building. As the time went on more people came to the science fair and to our stand. At first we had some issue with getting the printer started to show the people how it works. After little maintenance and some time we got it working again. Most of the visitors were really interested in our project. We had a lot of question about what our chicken breast was made, the nutrition, the printing and lots of other questions we happily answered. Most people also tried our spiced chicken and the reactions were divided. Some thought it was disgusting but there were also a lot of people who thought it tasted quite good. But this was not our main goal of the project. The structure of the chicken was important to us and about this the viewers were really amazed, how good it looked and felt as a real chicken breast. Eventually the science fair almost neared its end. A day full of question and interested people.
Afterward there was a lecture about prototyping and next starting cleaning our stand and moving everything back to our lab. We met up witch our coach George to talk about the day and the future of the project. With the group we also discussed about the improvement points. Now we are inspired by the positive reactions of the people who visited our stand.
In the incoming weeks we will report and extend our research in order to publish it as a paper in food journals.
With the ‘Science Fair’ approaching, our priority was to optimize our chicken breast and to try to produce a few successful samples to demonstrate to the world. We started by testing different variables, for example by changing the infill patterns of the prints or by trying to print without needle.
Friday further print experiments were made, trying out various infill methods and speeds or extrusion as we did earlier on (see weblog 20-10-2015). The main problem we encountered was with the extrusion, especially with creating a constant flow. Even with the first few prints we noticed that the material started clogging from time to time or stopped extruding, probably also due to clogs formed in the material. We expected that the clogs in the material were probably caused by the temperature of the material or other variables, such as the thin needle. However, we are still uncertain as to what causes the clogs to occur.
Also the extruder itself showed some mechanical issues. Firstly, the belt that pushes the syringe down to extrude the material kept tangling up and didn’t tighten around the syringe anymore which put the printing to a halt. We solved this by untangling it, fastening it with zip ties and checking it from time to time. Secondly, the motor started acting up and didn’t deliver enough force to keep the gears turning throughout the entire print. We realized that this wasn’t caused by the motor itself but by the electronics that drives the motor (Stepper Driver). That’s why on Monday we replaced the stepper driver and the motor worked fine after that. Finally, the last problem we faced was that one of the gears on the printer gradually came loose due to all the vibrations caused by the movements of the printer. To solve this we fixed the gear by gluing it and fastening the nuts and bolts with lock tight.
Furthermore, we tried printing without the needle to see if this would improve the extrusion. Using a bigger nozzle led to a faster printing time, but the structure became less similar to that of a real chicken breast due to the thicker lines. An interesting finding was that when extruding with a bigger nozzle it is possible to spray the salt-water solution on the filling before it touches the previous layer, which made it possible to immediately extrude a solid line in mid-air (similar to the printing of plastic).
To conclude, we decided to go for the thinner needle which gives a more accurate fiber structure to the samples, even though it will increase the printing time. However, in the future we could see printing with a bigger nozzle as a cheaper alternative to printing with a thinner needle.
Monday we continued trying to optimize the extrusion, by making as many prints as possible and trying to change the printer settings with every print to find the best print speed, infill method and speed for our final chicken breast models. Instead of printing life size chicken breast we chose to print smaller samples that would demonstrate sufficiently the different print methods without taking too long to print. Once we found in our opinion the best combination of settings that we could achieve we went on to print our first successful full sized breast!
By the end of the project all the documentation, settings and models will be published.
We noticed that the first few prints of the day, when the infill was still warm, the material would extrude smoothly without clogging. When the infill cooled down, the clogging started to happen more frequently. This is when we tried to use a heating element to warm up the infill to see if it was the temperature that caused the clogs to occur during the prints. For this we used a heat gun to warm up the material close to the nozzle and extruding right after and while applying heat. The result was that it didn’t change much; it might be a small factor but not a significant one. The conclusion that can be made regarding the clogs in the extrusion is that having a well premixed mixture with no clumps in it is the main thing when trying to avoid clogs. Having a heated mixture might help, but the difference isn’t significant enough to be a relevant factor. Another element that minimizes clogging significantly is the proper use of retraction. At first we had looked over a line in our layer change G-code. It would go to a stop position, extrude a bit and then continue on to print the next layer. However, we did not notice that after extruding at its stopping position, it would retract that very same distance back effectively leaving us with a loose belt and very little tension for extrusion. Some of the salt-water solution might have gotten into the nozzle, hardening our mixture and clogging the nozzle or simply leaving us with half empty layers. So by disabling the retraction every time it switched layers we prevented many of our clogging problems. In fact ever since we did this modification our results have been overwhelmingly positive.
The 3D printer modification
As said in a previous post we are using the custom made 3d printer available at the applied labs for the printing of the chicken breast. This printer was used to print PLA and therefore made several modifications. First of all the original printing head was removed and we placed our custom made, 3D printed, head in place of it.
The motor makes the gears turn. The Gears make sure that with the little power of the motor the material can be printed. The last gear (the biggest one) pulls the transitional belt. Because the transitional belt becomes shorter on the side of the syringe, the syringe is pulled down. This is done fluently with the use of the belt holder with a bearing inside.
Next to this the software used for the printing is modified for this food extruder.
Now the first organic chicken breast will be 3D printed. To do this we use the 3d model we obtained from the 3d scan and we use the lupine/Alginate recipe with 30% less alginate than set. The first print will be made with three outer layers filled with an infill with a linear cross infill of 98%. After each layer manually the saltwater concentration (double as prescribed in the recipe) was added using a plant sprayer.
At the beginning the print did not work out correctly. We changed the layer height, the printing speed and the extrusion rate settings to make the printing more accurate. This worked out. In total the printing time was about 50 minutes for the chicken breast with a size of 50*105*15 mm. At the end the extruder was not printing straight lines anymore and clogs arose in the print. Probably this was due to the incorrect height of the extruder in comparison with the printing bed. The real line thickness was not the same as the expected one. Possibly as well the resistance grew inside the nozzle which caused a delayed print. As a result we got the following:
The good things about this print are that the layers are not visible from the outside. Further the side has quite a smooth surface. The biggest downside is that the top was not printed correctly.
More important the inside had a really fibrous structure as can be seen below.
A small part of the ‘chicken breast’ is tasted by one of the team members and as he responded: “You could really feel the fibers in your mouth. Further it was completely solid.” So luckily there were no parts where the mixture could be squeezed out. The food had no good taste yet. It was neutral and a little bit salt, but not too much.
For the second print we mainly changed the infill pattern. Now we used a concentric infill. The bottom part was really nice and fibrous. But in next layers strings melted together and bobbles appeared. Therefore we stopped the print.
Now we used again the concentric infill pattern. Now we changed the infill density from 98% to 90%. In this way we hoped the lines would clog less likely. Unfortunately this did not work out the way we hoped it would be and again clogs appeared. Probably the concentric pattern is not efficient for the printing of the organic meat.
This time we tried to print the chicken breast again with the cross linked infill, which we used for the first print. Now we used again the 90% infill density (same as print 3). The start went fine but the needle constipated after a while. First it was letting through much less material which caused material concentration at certain places and later on no material at all was extruded and the printer jammed. In this print we saw that the layers did stick to each other. This could be due to an overflow of saltwater added. Otherwise we must think of using a binder for the different layers.
In the incoming days we will go on experimenting with 3d printing. The modification will be during making the mixture. We will blend the mixture longer than in previous trials. This way we hope to get rid of lumps which cause the needle to clog.
We will as well try to add some flavour to the food. We will try to do this with mixing some ‘chicken flavour’ species with the salt water solution.
As we want to create an organic chicken breast, it is important to know the shape of it. The chicken breast will be 3d scanned in order to make it a 3d CAD model. Several 3D scanning methods are tested.
It does work but there is no fluent surface. A lot of repairing will be required in order to use this file for printing.
This is a device which makes a 3D photo. For acquiring a full 3D image several photo’s must be combined. The 3D photos made were not very accurate. Details were not visible. And the 3 dimensional forms were not correct some times. Besides there was no clear subscription of how to make the full 3D model with the programme.
Autodesk 123D Catch
This programme works the best for the chicken breast. After making a wide series of photos of the chicken breast the programme made a fluent 3D model of it.
In order to see the 3D model of the chicken please click the link below.
We started the week with preparing for 3D scanning. Bought a raw chicken breast which we wanted to make a digital model off. First we started using an app(123DCatch) which turn several photos of the object into a digital 3D model. We didn’t succeed using this method and are hoping to do it next week using the Fuel3D scanner.
During this weeks coach meeting we discussed:
-Several 3D scanning solutions/options
-How we could find out the thickness and length of fibres in a chicken
-The possibilities of printing multiple strands or just one
-We will mainly stick to the recipe we got this far
-How to bind the strands of material we print. Maybe we need a binder or we should use less salt.
-That during printing the excess water should be drained
-How are we going to add the salt solution? Spraying or needling.
-When will we start printing? As soon as possible
We need to make some adjustment to it, so it can print meat replacers instead of plastics. We came up with several options to make this possible.
-Using a syringe to store the recipe
-Using a needle to extrude
-Using a spray or syringe to add the salt solution
-Using a motor to control the extruding
-Using a custom made printing head to print the material
New printing recipe
Last week we did experiments with the 30% less alginate mixture. We wanted to test if it would be possible to extrude the material with a small syringe using the original recipe.
The biggest difference between those recipes is the thickness. The 30% less alginate variant is easier to handle, it’s easier to extrude in the syringe. Also we tried if a different way of mixing the powders with water would matter. So far there was no influence. In conclusion we will stick to using the recipe with 30% less alginate for easier printing.
First we assumed the fibres made with the syringe wouldn’t thick together, luckily they do. On the picture u can see how they stick together. But we may need to find a better way to make the fibres stick together. Now the bond is weak. At our group meeting we thought maybe we can use a food binder like mazena. This way it could become a more a solid piece and simulate the chicken breast better.
To find the best possible recipe for the 3D printing we decided to conduct more experiments, changing the different variables to see what works best. We closely documented these experiments for more understanding and reference.
- Create a fibrous lupine-based product with 30% less Alginate.
This might create a product that has a higher fluidity, making it better suitable to extrude from a syringe or even a needle.
- Instead of adding CaCl2 try adding CaSO4.
The instructions mentioned that both salts might work, we want to try to see if it is as effective.
- Experiment with different salt concentrations.
The salt solution is a key factor in solidifying the fibrous lupine-based product, perhaps using a higher concentration solution could create a sample with more structure and, or strength.
- Less Alginate
Instead of mixing 20g lupine with 10g Alginate, we used 7gr. The rest of the preparation were standard procedure, so the only difference was the Alginate. This resulted in a mixture that, as expected, had a higher fluidity and was less of a gelatin fluid. It also was a lot smoother and had fewer chunks.
We even managed to extrude it through a 0.5mm needle, creating the possibility to extrude very accurately. An extra benefit is that the salt solution can reach deeper into the product, creating an extruded line that is almost 100% solid, as can be seen below.
In the rest of the experiments we continued to use the solution with 7 gr Alginate, partly to reduce waste, and partly for convenience.
- CaSO4 instead of CaCl2
As can be seen in the picture down-right, the calcium-sulphate solution looks milky white, instead of the clear look we got with the calcium-chloride solution. To get an equivalent molar amount of CaSO4, we dissolved (111/136*5,4) = 4,4 grams in 135 mL of water. We tested this solution on a couple of extruded lines of the product mentioned in experiment 1, by dripping it on the product with a syringe. For comparison, we did the same with the calcium-chloride solution, on a different extruded line. Immediately it became apparent that the calcium-sulphate solution was a lot less effective than the calcium-chloride solution. The strands of Lupine product were still very fluid, and hardly had any bonding, in comparison to the strands we exposed to the calcium-chloride, which were bonded nicely, and had a certain strength.
- Different salt concentrations
To indefinitely rule out the use of the CaSO4 solution, we tried creating a highe
r concentrated solution. For this, we added another 5 grams of CaSO4 to the solution we already had, making it a solution with a concentration of approximately 9.4 gr / 135 mL. Apparently doing this
crossed the maximum solubility boundary, as a lot of the salt could not dissolve. We tried the solution on a new strand of the product, and the effectiveness hardly improved.
After ruling out the CaSO4 solution, it was time to experiment with different concentrations of the CaCl2 solution. We did this by adding, consecutively, a factor 0.5, 1, 2, 3 and 4 of the original 5.4 grams, to (5 times) 135 mL of water. After creating the different solutions, we created 5 different strands of the product. These strands where then used to drip the solutions on, giving us 5 different strands to test and compare. To test the strands, we used the criterion Strength. We measured the strength of the 5 strands using a digital force meter. Because the strands had a varying thickness, we tested the each of the 5 strengths in three different thicknesses (as they all showed a thick, medium thick, and a thin part).
Remark: Because the strands had a slightly different thickness, the measurements might be slightly inaccurate.
A table showing the strength’s for each thickness of the 5 different strands:
|Concentration [gr/135 mL]||2,7||5,4||10,8||16,2||21,6|
|Strength Thick [N]||0,5||1,6||2||2||2|
|Strength Medium [N]||0,9||0,6||1,2||1,8||1,7|
The following graph represents the data noted in the table above:
Less Alginate seems to be a good choice for further use, as it has a more fluid and less gelatin structure, it is more suitable to be extruded out of a smaller hole.
CaSO4 can be ruled out as a solution to solidify the product with, because it has been proven to be a lot less effective than CaCl2.
A higher concentration definitely seems to be a good choice for solidifying the product. The chart shows that there is a certain inaccuracy because of the varying strand thickness. Nevertheless, a trend can be deducted showing that a higher concentration results in a higher strength of the strands. What can also be concluded from the chart is that it is very likely that there is a maximum concentration that has an optimal result. Judging from the three categories (thick, medium and thin) it might be best to use a factor 3, or a concentration of 16,2 gr/135 mL in the solution.