Case Study: Microfluidic Electromagnetic Swimmer & Microscope
The ABIOMATER project was an Horizon 2020 project in collaboration between several EU consortia. The project was focused on the development of novel magnetically actuated meta-materials. These devices were termed "swimmers" as they were designed to be inserted in fluidic channels and remotely controlled via external 3D electromagnetic coils. The application of this project was to provide life sciences with an injectable robot that could swim within the body to carry and deposit a drug payload at specific target sites.
Platform Kinetics role was to design & develop the actuation (3D electromagnetic system) and the imaging/tracking instrumentation and software.
Design & Prototyping
Our development process usually starts with 3D CAD (SolidWorks) designs, these designs allow us to iterate through different versions capturing the specifications physical requirements and enables our customer to see where the project might be heading.
In these designs we can pull together off-the-shelf parts and custom machined parts. In this example we were able to really optimise the coupling between the 3 axis coils and the microscope objective/imaging.
Coil Design & Manufacture
The coil assembly was required to have a working envelope of 50 x 50 x 25 mm with a uniform magnetic field up-to 25mT. Using field calculations and the physical design constraints we were able to reach an optimised design. Each coil was designed to use a custom machined form, each coil form connecting to create a self contained assembly.
The coils were wound in-house. They were tested and chacterised using a network analyser (for their impedance) and a 3 axis gaussmeter which allowed the field to be mapped across the working envelope.
The micrsocope was designed as an upright configuration with an epi-illumination LED light source (490nm) the brightness of which could be manually controlled. The camera was a Mikrotron Eosens Mini, which was required to run at 1000 FPS to capture the swimming motion of the devices. A single objective could be used and were typically 10X or 40X (this was later changed to be selectable between two). Nikon eyepieces were fitted to allow the operator to observe the experiment if the camera was not required. The majority of the optical parts were from Thorlabs CERNA range.
Electronics & Control
The electronics and control system was produced in a 19" rack format. Each coil had its own amplifier bay containing 100VDC power rails and 10A amplifiers. Each amplifier could produce a sinusoidal waveform up-to 300Hz. The 3 amplifiers were synchronised using a custom central waveform control board which received commands over USB from the PC. The PC was also in a rack bay and ran a python based UI to allow the operator to set-up and run their experiment.
The software was based on python and used Wxpython to act as the UI. The software served to control the electromagnetic field (frequency, amplitude and phase), but also to capture and analyse the motion of the swimmer. The camera could be configured via the UI and some basic capture and tracking functions were implemented using techniques provided via openCV.