Microbio Automatic Photography Tool

Description:

A tool to automatically take photographs of petri dishes.

• Holds up to 10 petri dishes
• Frequency of photographs is configurable between 4-24 hours
• Create time lapse images of bacteria and fungus growth

https://bioMAPT.github.io 

Problem:

We had a set of inoculated petri dishes and intended to photograph the plates at regular intervals to document growth. However, as the number of plates grew, it became very tedious and time consuming to line up each plate, focus the camera, get the lighting just right, take multiple pictures of each plate, and make sure we gave each and every picture a unique identifying file name. We needed a way to automate the photographing process so that the lighting and positioning was uniform, and labeling was done automatically. It would also free us from a repetitive task so that we could focus on analyzing the results. 

To solve our problem, we created the MAPT Tower, which stores inoculated petri dishes and takes pictures of them at regular intervals. It opened up the possibility of making some very interesting time lapse videos of microbial growth!

BOM:

1x Raspberry Pi Zero W

1x Creality V1.1.4 control board (from Ender 3) or BTT SKR Mini E3

1x DC-DC Voltage converter board 

1x Pi camera

1x NEMA 11 Stepper Motor

1x T4 150mm lead screw and nut (cut from 200mm lead screw)

2x NEMA 14 Stepper Motors (Ender 3 z-axis motor)

2x T8 Lead screws and nuts (Ender 3 z-axis lead screw)

2x 3mm or 1/8” rods (cheap brass rods are available from hardware stores but bend easily, hard steel rods are available online)

12v 100N 22mm electromagnet

1x Pi camera ribbon cable

2x RJ45 Keystone jacks

2x Endstop switches (eg. from Ender 3)

Adhesive 5V LED strip

1x 5.5mm Female Barrel Power Jack (11.5mm diameter)

1x Ethernet cable (>40cm)

1x micro-USB cable (not mini! Must fit motor control board)

1x mini-USB OTG adapter

Coiled cables recommended

Cables/wires for motors, endstop switches, magnet, LED, etc

10x 4x10mm or #8x1/2in or similar size ferromagnetic screws (eg. zinc-coated)

M2 & M3 screws and nuts

M2x3.5, M3x5 threaded inserts (length may be 3-6mm) 

Tools:

Soldering Iron

Small electronics screwdriver

Zip ties

Print List

For the Petri Dish Tower:

10x Petri Dish Trays

2x Tower Racks

1x Tower Base

For the Motor Tower:

1x Motor Base Plate

1x Motor Carriage

1x Magnet Mount

1x LED Ring

1x Camera Mount

Recommended Print Settings

PLA (PETG, ABS, etc will likely work as well)

0.2 mm Layer Height

0.4 mm Nozzle Size

No supports

Brim on LED ring only

Columns on LED ring and camera mount can deform if layer time is too low

See “MAPT Build Instructions.pdf” for build instructions