summer 2020 Design Prompt Overview

A challenge in developing effective biomedical technologies and therapies is the difficulty of shaping clusters of cells into detailed three-dimensional (3D) structures. To address this challenge, the UF Soft Matter Engineering Group requests the complete design and fabrication of 3D Bio-Printers that mount to the turret of the lab’s Nikon Eclipse Ti confocal microscope. The purpose of this 3D Bio-Printer is construction of biostructures in a Liquid-Like Solid (LLS) medium via deposition/retrieval of cells. For purposes of biomedical and mechanical engineering research it is desirable to carry out building of biostructures in real-time and visualized under confocal microscopy. So, the 3D Bio-Printer and the microscope must be able to function simultaneously in parallel.

Need to create high-resolution structures from soft biological materials has driven existing 3D printing technology far beyond the traditional practice of liquefying, extruding, and re-solidifying solid materials as seen in conventional rapid prototyping processes. It is now possible to shape liquids in 3D space by capitalizing on LLS exhibiting large, reversible rheological changes resulting from small physical or chemical perturbations. However, with few exceptions relegated to one-off research applications, it was practically impossible to reproducibly form soft living materials into complex 3D structures at high spatial resolution.

The aim of this project is to convert designs for existing highly-specialized laboratory prototypes into a commercially viable line of products. We need a 3D Bio-Printer that can print complex living cell structures into LLS that is 1) repeatable, 2) reliable, and 3) robust enough to be mass produced for sale to commercial and industrial laboratories. Potential early adopters of these machines will be drug companies, biomedical device manufacturers, and biomedical research institutions. The UF Soft Matter Engineering Group wishes to engage student teams from the EML4501/4502 Capstone Design sequence to develop commercial-quality 3D Bio-Printers capable of producing living structures by leveraging the unique properties of soft matter.

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Customer Needs

The following is a list of requirements given to us by our Customer, UF Soft Matter Engineering Group. Controller design is not within the scope of this project; however, the mechanical system (including motors, actuators, etc.) must be capable of meeting these requirements. Printers will be controlled using a Smoothieboard 5x, and extra credit will be given for designing for compatibility with this controller type.

The 3D printer will be mounted to the condenser turret of a Nikon Eclipse Ti confocal microscope. Coarse motion of the axes will be handled by the microscope operator. The only motion required is that to translate the stages within the print volume.

General Requirements:

1. Mountable: Printer must be mounted to the condenser turret of a Nikon Eclipse Ti confocal microscope
2. Size: Primary structure must fit within a 100 mm cube
3. Weight: 200 g max
4. Linear accuracy: < 1 cell diameter
5. Linear speed: Min ~ 1 μm/s, slower is better; cannot cause LLS instabilities at high speed.
6. Maximum print extents: Must be able to print through the full volume of a single well of a standard biological 96 well plate. Z-travel should be equivalent to X/Y max.
7. Motion must be transmitted to printer stages from a remote source. Motors are not allowed to be mounted directly on 3D Bio-Printer stages. This means that no motors are allowed to be connected to or within the 100 mm cube defined above. No piezoelectric actuators can be used as they are not controllable with a Smoothieboard 5x controller.
8. Feature size: Must be able to print experimentally relevant feature sizes.
9. Cost: Sale price point is $4000.
10. Product Lifetime: 3D Bio-Printer will be in use for up to 8 hours per workday. Must last a minimum of 5 years of continuous use.

 

Print Head Requirements:

11. Maximum flowrate: Controlled by feature size being generated. Features must be experimentally relevant sizes for current research.
12. Alignment: At middle of travel, X and Y axes must be aligned with optical axis within accuracy limits and constrain needle to within 1 degree of vertical.
13. Print Material: Print head must be capable of both depositing and extracting material
14.  Print Medium: Printers will be depositing/extracting a fluid with an approximate viscosity of water and a yield stress of around 10 Pa. The extraction tip must move within this medium.
15. Tip Disposability: Tips must be either disposable or reliably sterilized

 

Additional Requirements:

16. No metallic or bio-reactive wear debris can be produced
17. Able to sterilize with common laboratory methods
18. System will need assembly/disassembly by a lab technician (i.e. not an engineer)
19. Printer will be operating in a biosafety clean-room environment (BSL-1)
20. Holding/dispensing print material will not kill cells

 

Extra Credit Requirements:

21. Controllable: Controlled via a Smoothieboard 5x