To fabricate a highly delicate and clean silicone microchip with micro scale channel structures, the first required step is to spin-coat a light-sensitive SU-8 photoresist evenly then dispense a harsh developer to cleanly clear off unevenly settled end-edges at the edge of the circular silicone chip (called the edge-bead remover procedure). If this procedure is not carried out with precise control, the flatness of the deposited photoresist will not be within the tolerance range, which will result in uncontrolled channel dimensions. I wanted to create a user-friendly developer dispenser that is easy to use and has accurate micro pump for precise pneumatic control as well.
What it does
LCD-screen touch controller allows users to set precise flow-rates, exact amount of time of dispense, for several steps if necessary. The flow-rates are determined by choosing different duty-cycle for the pulse-width-modulation for the micro-pump inside this device. Once the user finish choosing all the settings, simply click the "Start" button to begin the dispensing process.
How I built it
From scratch to finish, I had to start with setting up the internal system to work out well as I imagined. Took quite a while to get the electronics set up to work well. Then, connecting the LCD screen with my microprocessor and reprogramming to control everything with the LCD screen. Cad-ing up the custom case for this was quite fun. Took a while, but came out quite nice with a delicate look too done with 3D printing.
Challenges I ran into
Harsh fluid to be dispensed melted some of my components. Choosing the right materials was quite difficult. Controlling the drips falling off after each runs ruins the silicone chips. Being able to make my device drip-free was a challenge that took a while to solve.
Accomplishments that I'm proud of
NO drips at the end of the run, good design overall, good usage in cleanrooms, can be built anywhere with some experience and access to 3D printer.
What I learned
Precise motor control, LCD touchscreen controlling the entire assembly.
What's next for Smart Fluid Dispenser
Switching different fluidics, mixing fluids prior to dispensing, more advanced display technology.