Building a fluidic computer
Any computer requires two features. First, all the basic elements – electrons in a classic computer but droplets in our computer - should be controlled in a synchronous manner. Second, these elements should interact with each other and perform logic operations.
How do we propagate droplets in a synchronous manner?
A bias magnetic field, orthogonal to the chip, polarizes the droplet. A second magnetic field, in-plane with the chip, and periodically rotating, polarizes the “I” & “T” bars and thus acts as a clock for the system. This enables synchronous and parallel manipulation of any number of ferrofluid droplets on permalloy (soft magnetic) tracks.
We have built the following experimental setup to run droplets on our chip:
The fluidic chip is placed inside a single coil that provides the bias magnetic field. Around the single coil, two orthogonal Helmholtz coil pairs are placed thus providing the in-plane rotational field. The optical system is also displayed, showing the input port for the LED light source, the light collimator lens and the diaphragm. Also, the whole optical path is illustrated starting from the fluidic chip and continuing to the objective lens, the beamsplitter, a 90 degree mirror and additional collimation lenses, leading up to the sensor of the high-speed camera. The high speed camera is mounted on a X-Y translation stage on top of a lab jack. The experimental set-up is assembled on an optics table.
How does our computer operate logic operations?
i) First, what is a logic gate?
ii) How do we implement a logic gate in our circuits?
In our computer, a logic gate is defined by a unique junction geometry that receives, as its inlet ports, droplets propagating on different tracks of “I” and “T” bars. A magnetic repulsive interaction force prevents the incoming droplets from merging and diverts them to specific outlet ports.
iii) How do our experiments with logic gates look like?
Visit the "explore the paper" section!
A few example of designs... (to be moved to the sections "Gallery of designs")