...
- Normally brewed overnight
- Regular cold brew is normally steeped for 10-12 hours
- Can be brewed faster under higher pressure
- Pressure of compression will be tested
- Use a french press/aeropress method to compress the grounds
- Pressure of compression will be tested
- Will be brewed during launch and using room temperature water
- Will have a control group that will be brewed using regular cold brew methods on the ground
- Grounds
- Coarse
- Will be bought pre-grounded (from whatever company sponsors us)
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Possible Development of a cold brew design?
10/10/24
Spine:
- Materials:
- Model section of spine (focus on vertebrae or discs?)
- Upper spine (neck area) - feels the most force because head is heavy - part of the spine that becomes weakest in older adults
- Lower spine - for someone with a medical condition
- Model section of spine (focus on vertebrae or discs?)
- Brace (non-invasive)
- Extra: skin like material to see how much damage the brace would do
- Challenges:
- How will the brace enact force on the test spine
- Spine has bone and ligament sections. Do we also need to model the squishy ligament sections for this to be accurate? I feel like the squishy ligament sections would respond most to compression (more squishy than bone) so maybe idk
- How to brace non-invasively inside the payload?will the brace enact force on the test spine
- Finding a good fake bone material
- How to brace non-invasively inside the payload?
- What are we measuring? How will we collected data? - displacement, something to measure forces between vertebrae?
- Do we need to simulate weight of the head? - scale down the spine and just add weights on top
- Plan:
- Do we want multiple brace designs
- At least one braced ‘spine’ and one control Do we want multiple brace designs
- Create brace similar to traditional medical brace
- Angled spine to be more realistic to how astronauts actually sit in rocket
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- Individuals in air travel have often been reported to experience hypoglycemia (too much insulin is delivered by the pump during takeoff?)
- Materials
- Insulin/IV drip
- Force comes from gravitational pull, so the drip bag must be kept higher than the place insulin/IV fluid is delivered
- Mechanical IV/ insulin pump
- Functions like a syringe
- Doesn’t function based on gravity, will it still be impacted by the increased g forces?
- Delivery site
- Synthetic model of human fatty tissue?
- Insulin/IV drip
- Mechanical IV/ insulin pump
- Challenges What are we measuring?
- Delivery site
- Challenges
- Flow rate through a small tube? Fluid delivered somewhere?
- Goal to maintain a constant flow rate (drip rate) throughout flight?
- What are we measuring?
10/13/2024
asdf
We did a intense brainstorm and design session for the updated payload project. We decided on the neck brace, and conducted research on different elements of the project.
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- Cervical Myelopathy: https://www.hopkinsmedicine.org/health/conditions-and-diseases/cervical-myelopathy
- Can it also be prevented with cervical collar braces? Most likely
- Results Results from compression of the spinal cord in the neck
- Often treated with cervical collar braces
- Can it also be prevented with cervical collar braces? Most likely
- Cervical collars:
https://www-sciencedirect-com.ezproxyberklee.flo.org/topics/medicine-and-dentistry/cervical-collar
...
- Force Capacity = 50 kN/11250 lbf
- Is this limit going to affect the accuracy of our measurements of the stress/strain imposed on the spinal structure?
- Note that the forces we will be loading onto the apparatus likely don’t need 50 kN to simulate the maximum load case adequately.
- Is this limit going to affect the accuracy of our measurements of the stress/strain imposed on the spinal structure?
- Min. speed = 0.001 mm/min
- Min. speed = 0.001 mm/min
- Max. speed = 762 mm/min
- Max force at full speed = 25 kN/5620 lbf
- Position Control Resolution = 1.8 nm
- Able to provide a relatively accurate amount of force onto the entire spine, which we still have to determine.
- Specs
- Note that we have:
- Which is the maximum space we will have to accommodate the entire apparatus ( given we’re going to be ditching the CubeSat design because of the want to replicate the 75-degree angled decline, we’d have to design some accommodation for this simulation that can fit not only within the
- Able to provide a relatively accurate amount of force onto the entire spine, which we still have to determine.
- Specs
Procedure:
- Enable the machine and for legacy machines you have to wait for the self-test to run on the device, allowing for software to run.
- Tools:
- Buttons: able to perform big movements of the crosshead
- Thumbwheel: for more precise movements of the crosshead
- Red Button ( able to Red Button ( able to stop unexpected movements of the crosshead )
- Spring Device ( used to mitigate the effect of unexpected movements of the crosshead )
- Remote Buttons: able to perform big movements of the crosshead
- Thumbwheel: for more precise movements of the crosshead
- Calibrate the device every 8-12 hours
- Grips ( depending on how big the apparatus is, we’d have to design for this )
- It’s the same idea for holding for the limits on the grip ( we’d have to attach an air hose to actuate the grips on the apparatus
- Use the specimen aligning device to help with aligning the apparatus onto the grips
- Move the limit switches according to the movement to prevent collision of the crosshead to the lower base of the grips
...
- What needs to fit?
- At least two simulated spines with weights (simulating head weight) and braces attached, along with all sensors.
- How much space do we have to work with?
- 10 cm x 30cm
- What weight do we have to work with?
- 8.8 lbs
- 2.25 lbs of boiler plate mass
- How do we attach the “fake spines” to the structure?
- Option 1: 3D print stabilizers to attach to the top/bottom which attach to the frame.
- Option 2: Connect with some form of glue/epoxy/resin to the frame directly.
- If the spine(s) is “angled”, how do we minimize wasted space? Not much space for an angled spine
- At 0 degree angle, length < 30 cm
- Maximum angle from vertical can be 19.84° - length < 31.62 cm
- Usual angle from vertical is 75-85°
- Spine length < 10.35 - 10.03 (basically 10 cm)
- Not much space for an angled spine
- What sensors are going to be as a part of payload, and where do they need to be (relative to the spine)?
- If the spine is placed vertically, sensors can be arranged around the spine, and at the base. They can also be attached directly to the spine/brace.
- If the spine is horizontal, there is room for either more sensors or more spines.
- What weight is going to be on top of the spine?
- Depending on how scaled down the spines are, the weight will vary (see section 8)
- What scale are we using?
- A human spine has an approximate length of 71cm (male) to 61cm (female) in the neck region (first seven vertebrae, C1-C7)
- If the simulated spines are approximately 30cm in length, the simulated head should be around 3.1 lbs (assuming average head weight is 7.5lbs).
- If the simulated spines are approximately 10cm in length, the simulated head should be around 1.05 lbs (assuming average head weight is 7.5lbs).
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- 3D Printed Spine ✅
- Neck mold
- Springs?
- Alternatives:
- Foam
- Silicon or silicon gel
- Alternatives:
Concerns:
- Putting the vertebrae inside of a liquid gel mold that will then solidify will fill every crevice of the neck vertebrates and COULD prevent the compression
- Choosing the right material for modeling intervertebral discs
...
- Design Requirements:
- The highest temperature experienced is going to be the exterior temperature of the environment which is 100 F
- We want extremely small tolerances so minimal changes during the manufacturing process
Material | Cons | Pros |
Dragon Skin 10 (Needs a degassing process to remove excess bubbles, have to see if we have a vacuum chamber, and this may apply to other materials)
| Have to create subtractive molds for the portion between the bones that are almost completely accurate Shrinkage is possible, depending on the conditions | Superb service range temperatures ( -65°F to +450°F or -53°C to +232°C ) Molds are reusable so its easy to create multiple Skrinkage, though possible, is minimized ( <.001 in. / in. ) |
Soft Flexi Foam | Has no resistance to compression Have to manufacture the soft flexi foam so it accurately reflects the disks | Easy to conform to the vertebrae because of its “foamy” nature |
Silicon - What kind of silicon are we using? I think Dragonskin is also a derivative of silicon | ||
Ecoflex 00-50
Should be Ecoflex 10 or 20 ( available on the website ) if it wants to simulate human tissue | Basically has the same pros/cons as Dragon Skin 10, with the curing process and temperature range Able to simulate the compression of the disks as it retains its shape following compression | |
Ballistic Gel Maybe we can do a combination of Ballistic gel with some other material to simulate the spine | Impact forces Environmental temperatures, the shelf-stable temperature is -10OF - 95 OF | Certified because of extensive use in the medical industry |
Medical-grade plastic (polyethylene) |
Shopping List Materials:
Material | Price per unit | Quantity (# units) | Purpose |
SimuBone Filament Roll | $98 | 1 | 3d printing material for vertebrae - each set of vertebrae uses 20 grams of material (1 spool comes with 750 grams) |
FlexiForce A201 Sensor (8 Pack) https://www.tekscan.com/products-solutions/force-sensors/a201 | $153 | 1 | Measure the compression forces on the spine. |
Raspberry Pi Zero | $25 | 1 | Breadboard with an MPC3008 integrated circuit converts analog signals from force sensors into digital signals that can be read by Raspberry Pi Zero. Raspberry Pi Zero retrieves the data. |
3.7v 18650 cylindrical lithium-ion batteries (2 Pack) | $19.95 | 1 | Powers the system. |
Questions To Ask
- We are members of the MIT rocket team. We are launching a rocket with the purpose of simulating the effects of the g-forces on the cervical spine with and without a neck brace of our own design. We wanted your expertise to choose the materials for our spine model. Specifically, which material would be best for the intervertebral discs and a “container” to hold the model representing the human neck.
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- Putting the vertebrae inside of a liquid gel mold that will then solidify will fill every crevice of the neck vertebrates and COULD prevent the compression
- Choosing the right material for modeling intervertebral discs
November 10, 2024
Young’s modulus of intervertebral disk: 30 MPa in the linear elastic regime (that’s actually really high)
Words when presenting: ultimate strength and young’s modulus
Possible Links:
Here is a type of polyurethane foam with roughly the correct density that gives a Young’s modulus in the 10-30 MPa range: https://makerstock.com/collections/foam/products/cnc-and-modeling-foam-rigid-polyurethane-foam-high-density-8lb-ft3
Material | Young Modulus (basically how much it deforms under stress) | Stress-Strain Curve | Ultimate Strength |
Intervertebral Disk | 30 MPA / 0.03 GPa | ||
Rubber (Small Strain) | 10-100 MPa | ||
0.517-62.1 MPa | 0.138 - 165 MPa (tensile strength, ultimate) | ||
150-520 MPa | 10.3-18 MPa (tensile strength, ultimate) | ||
Polyethylene | |||
UHMW Polyethylene (used in actual disc replacements) | 760 MPa | ||
Polyurethane Rubber | 6 MPa | 25 MPa | |
EVA (Ethylene Vinyl Acetate) (this is what shoe soles are made of!) | Pure EVA, 0.3 wt%, 2 wt% stress-strain curve, Young’s modulus, elongation | ||
0.16g/cm^3 polyurethane foam | 15 MPa | ||
Memory Foam (a type of polyurethane foam) | |||
Notes for substitute intervertebral disc material:
Lumbar spine stress-strain curves?
From this article: “Stress–strain characteristic curve of the intervertebral disc at different strain rates. Both the yielding and cracking phenomenon occur at fast and medium loading rates, while only the yielding phenomenon occurs at slow loading rates. (A) The mechanical behavior in L1–2 Segment; (B) The mechanical behavior in L3–4 Segment; (C) The mechanical behavior in L5–6 Segment.”
Note: Material for head weight
Material | Height | Density | Radius | Outer Diameter | Shape | Weight (not accounting for hole) | Price |
Brass | 0.303 to 0.315 lb/in^3 | 1.5 | Cylinder | 3 lb | |||
Stainless Stain | 1.48 in. | 0.27 to 0.29 lb/in^3 | 1.5 in. | 3 in. | Cylinder | 3lb | $86.70 for 6 in |
Low-Carbon Steel |
Vertebrae
https://www.thingiverse.com/thing:4801717
Proportion Head to Vertebrae:
Piece | Real Human | Prototype |
Head Weight | 10 lbs | 3 lbs |
Vertebrae Weight | 44.1 grams | |
Head Weight | Vertebrae Weight | |
Real Human | 10 lbs | 44.1 grams |
Prototype | 3 lbs | 20 grams |
Determination of Proportion:
50% scale for the vertebrae, 30% scale for the head (maximum size for each permissible by dimensions of payload)