With all of the power of the Arduino platform, you can often build simple control devices which can allow for much more accuracy than if done by hand, without needing all the high grade equipment right away.
Usage: Accurate Volume Dispensing
This has been implemented using LEGO already, but can be built using Arduino, for a highly customisable approach.
In the below example we will upcycle a CDROM mechanism as an alternative to the LEGO linear actuators
Why Linear Actuators?
Small linear actuators are ideal for the job, and essentially consist of a small motor, with a screw attached, with the piston being wound up and down the rod. This means that they need to do 1 turn to move only 1 pitch length down the screw, making them extremely accurate (and powerful).
Dispensers can simply be standard inexpensive syringes, which can be mounted to the linear actuators in a variety of ways depending on what is in use (and could be as simple as elastic bands).
As they come in a variety of sizes, we will need to calibrate our mechanism to dispense the correct amount from each dispenser type in use.
For now we will only calibrate a single dispensers' movement, to give us a 0.1ml sample per time.
In our example we will wire the stepper motor to the L298N Stepper Motor control board, and wire the control board to the Arduino as shown below (an External 5v supply should be used to power the 5v rail of the motor driver).
Which when you have finished should look similar to the below....
Once the hardware is hooked up, we can quickly put together our Arduino code, and go through calibrating our setup.
Here we will use the "Stepper Library" which allows us to easily run the stepper motor without needing to understand how stepper motors work.
Initially we will use the Visual Micro Serial Debugger to calibrate our system, to save time, and ensure we are dispensing as accurately as we expect. This requires us to mount the dispenser of choice, and then run the code through to perform a movement. If this is incorrect, amend the values until you acheieve the movement desired.
Example Code shown in the below video is available at this location
In the below video you can see how we setup our code, upload it to our board, and calibrate our dispensing system while it is connected to the PC.
View the Video on Youtube
Interfaces / Monitoring
This setup can be expanded, and depending on the board in use further web interfaces, and remote monitoring of the systems can easily be achieved using the Arduino platform, as well as environmental monitoring for when these factors affect the degredation of the sample.
Populate Sample Plates
The same mechanism could be mounted to a 3D printer (or similar 3 axis machine) to allow samples to be dispensed automatically into well trays accurately, or other mediums.
Minature linear actuators can be purchased from a variety of suppliers, for a wide range of travel length, speed and torque.
The mechanism used above could be reduced with some 3D Printed parts (similar to this)
Find Out More
Serial Debugger Explained