Applications and Implications
- Propose a final project masterpiece that integrates the range of units covered
Final project requirements
- project should incorporate 2D and 3D design
- additive and subtractive fabrication processes
- electronics design and production
- embedded microcontroller interfacing and programming
- system integration and packaging
- where possible, you should make rather than buy the parts of your project
- projects can be separate or joint, but need to show individual mastery of the skills, and be independently operable
What will it do?
My plan is to develop the Motorized translational microscopic stage. For the experiments I'm doing with optical tweezers, sample movements have to be precisly controlled. For this purpose, 2 or 3-dimensial motorised stages are usually used. Unfortunately, the price of these kind of stages is quite high, plus they can't be freely adjusted to different kind of setups.
The gold standard of reliable stages are commercially produced solustions with a special software to control the movements of the stage. One good option is Thorlabs XYZ stage. The price of this stage goes up to thousands of euros. My idea is to create the cheaper analoge of XY stage.
Fig 1. Example of the comercial translational XYZ stage.
Who's done what beforehand?
Some of the stages designed "in house" previously:
- Microscope Automated XY Stage (more)
- 3d printed linear stage
- A 3D Printed Toolbox for Opto-Mechanical Components
- Similar projects on STLfinder
- Microscope Automated XY Stage
- Github open project on 3D printed translation equipment
- Stage with a built-in backlight
- Openstage: A Low-Cost Motorized Microscope Stage with Sub-Micron Positioning Accuracy. Approximate cost 350 EUR
- Project from fabacademy 2016
I would HIGHLIGHT the projects:
- A low-cost and high-precision scanning electrochemical microscope built with open source tools, less than 300 dollars, submicron (500 nm) resolution stage based on potentiostat.
- μ SmartScope: Towards a Fully Automated 3D-Printed Smartphone Microscope with Motorized Stage, XY direction of the sample is controlled by servo motors (Hitec HS-55 5 V), Z focusing system - a cheapest stepper motor 28BYJ-48 5 V coupled to M2 Threaded Rod, resulted to the step size 0.763±0.098 μm.
- Design and construction of the motion mechanism of an XY micro-stage for precision positioning.
- Step-by-step guide to building an inexpensive 3D printed motorized positioning stage for automated high-content screening microscopy, approx. EUR 250 EUR, averaged step size (resolution) is 5 μm.
However, for my purpose the embedded backlight is neccessary, and I hope for the lower total costs.
What will you design?
- Platform-case from 4mm Plywood to mount all the hardware parts.
- 3D-printed parts from ABS
- PCB run by ATmega 328P to control the motors of the stage and the PCB run by ATtiny44 for the backlight control (LED light with a brightness control)
- Joystick to control the stage movements OR just a serial communication
- Android application, if I will have enough time
- Stepper motor mounts
- Backlight case
- Sample holder
- 3D-printed: 2 support legs (X axis)
- LED housing (acrylic laser cutting, or ABS 3D printing)
- Joystick housing
What materials and components will be used?
Where will come from?
- Components available at local Fablab:
- PCB: Microcontroller ATmega328P, stepper motor drivers A4988, resistors (0Ω, 499Ω, 10Ω), capacitors, male and female headers, resonator, power jack
- LED lights (NEOPIXEL)
- Linear guids - aluminuim rods, couplers
- Lead Screw 8mm Thread With Copper Nut
- Screws M3, M4
- Materials available in local Fablab:
- 4mm Plywood
- ABS
I'm still thinking about the proper design of the stage and its control, therefore I have to dedcide on the stepper motors types to use. In case I will need the stepper motor of higher performance or some extra components I'm goind to order them from Digikey (delivery takes about 1 week).
How much will they cost?
The preliminary cost estimation of the materials is about 92.78 EUR, plus some extra components for PCBs, Ip hope will male a total price about 100 EUR. The final updated list of components will be posted on the Project Development page.
Preliminary list of components:
| Component | Properties/Function | Qty | Buy/Produce | Price, EUR |
|---|---|---|---|---|
| ROB-10846 Stepper motor | 3A, 400 steps | 2 | Digikey | 33,08 EUR |
| Threaded rod or lead screw | Pitch 2 mm , length 300 mm | 2 | Available at local Fablab | ≈10 |
| Flexible 8mm - 5mm coupler | Coupler between the motor shaft and threaded rod | 2 | Available at local Fablab | ≈2 |
| Stainless rods | Holding the construction | 5 | Available at local Fablab | 6 |
| ???Limit switch DG23-B1LA | 3 | Digikey | 9.12 | |
| Ball bearing | Holding the moving stages on the metal rods | 6 | Available at local Fablab | ≈2 |
| NEOPIXELs or White LED Backlight Module | Backlight | 1 | Digikey | 2.30 |
| TMC2209 SILENTSTEPSTICK | STEPPER MOTOR DRIVER (Smooth microstepping up to 1/256 step!!!) | 2 | Digikey | 27.10 |
| ATtiny44 | Motor and backlight control | 1 | Available at local Fablab | 1.18 |
What parts and systems will be made?
Design will incorporate the following fabricated parts:
- Plywood case for electronics
- 2 Stepper motor mounts to hold the motors, to be attached on the platform
- 2 Couplers
- 3 sliding stages
- 2 support legs
- Backlight housing (acrylic laser cutting + sand blasting and 3D printed case)
- PCBs for ATmega328P and ATtiny44
Fig 2. Preliminary Design of the motorized XY stage
What processes will be used?
- CAD
- 3D printing for the mount components
- Laser cutting for the the sample holder and 4mm Plywood platform
- Electronics design
- Embedded programmimg
What questions need to be answered?
- At the current stage I'm not sure how to connect the boards, or sold the microcontrolles on one single board.
- What maximum resolution can I achieve?
- Will mechanical parts of the design influence the performance? The imperfections of 3D printed parts and Plywood can be the limiting factors and implicate the alignment
How will it be evaluated?
The stage performance will evaluated in terms of precision and resolution of the mechanical movement, particularly in terms of the horizontal (XY plane) direction.
- Mechanical design and alignment for stable performance
- The resolution of the stage should reach 5-10 micrometer/step
- Backlihgt brightness should be enough for the sample lightning
Usefull link for calculation the number of steps for the system:
Fig 1. Calculation of number of steps electronics need to generate to move the axis by 1 mm.
| Leadscrew pitch, mm/rev | Full step | 1/2 | 1/4 | 1/16 |
|---|---|---|---|---|
| M6 (1 mm) | 5 um | 2.5 um | 1.25 um | 0.31 um |
| M5 (0.8 mm) | 4 um | 2 um | 1 um | 0.25 um |
