Inkjet Printer
Description
The inkjet printer was designed for the dispensing of low viscosity solutions containing metal oxide precursors. These solutions, also called inks, are typically formulated in polar solvents such as water or alcohols and modified using more viscous or more/less polar additives to obtain fluid properties that make the ink "jettable".
The mechanics of the system involve two translation stages for x and y motion of the stage and one translation stage for z motion of the printhead.Â
The stage houses the substrate upon which inks are deposited.
The printhead contains the ink to be printed.
My design is based on a commercially-available glass nozzle with 50 micron diameter, designed by MicroFab.
The vision system involves two cameras, an upright "fiducial" camera pointing at the substrate and a lateral camera for inspecting drop formation prior to printing.
The fiducial camera allows for printed patterns to be inspected after printing.
The drop inspection camera allows for the jetting waveform to be adjusted to control drop formation for stable printing.
System Components
A temperature controller is used to set the substrate temperature or platen during printing. This allows the rate of solvent evaporation to be controlled, affecting film formation.
A pressure controller provides a back pressure of gas (nitrogen) to maintain a stable meniscus at the tip of the nozzle.
The motion controller controls the up/down and side to side action of the linear actuators.
The jetting controller applies a voltage waveform to drive the piezoelectric printhead.
Note: a commercial controller, with software, was used, however, a software-controlled arbitrary waveform generator and a voltage amplifier would also suffice.
The vision controller controls the two cameras for drop inspection (drop camera) and sample inspection (sample camera or fiducial camera).
Integration of the subcomponents of the system is done using MATLAB and serial/parallel links with the various hardware components.
Some pictures showing the system in action are given below, tested using a 50:50 mixture of ethanol:ethyleneglycol.
Example: phrase "H.O.N.E.S.T. LAB"
Seen through fiducial camera
Example: the "UT" symbol
Seen through fiducial camera
Example: phrase "H.O.N.E.S.T. LAB"
Captured from mobile phone.
Example: phrase "Martin Mouska"
Captured from mobile phone.