Projects
One Surface, Three Ways
Left: 1 oz (35 um) copper, 4 mil (0.102 mm) polyimide substrate, outsourced fab (chemical etch)
Upper Right: 0.2 mm Electrifi Conductive Filament, 1.6 mm NinjaFlex Neon Glow substrate, 3D Printed (Prusa MK3S)
Lower Right: 1 oz (35 um) copper, 62 mil (1.575 mm) Duroid substrate, laser etched (20 W fiber laser)
Fiber Laser
This was the inaugural run of the lab's new 20 W fiber laser!
We embarked on this journey thanks to the abundance of pre-holiday ads promoting Glowforge and other home hobby CO2 lasers. Before laying down any cash, I visited the Fab Lab where Adam helped me experiment with copper foils and 2-layer PCB's on his 75 W CO2 laser. We quickly learned that CO2 is NOT good for metals.
Searching online, I found that this is due to a wavelength mismatch. I found that fiber lasers are the right tool for the job. Better yet, they are cost competitive and require less maintenance than CO2. I gained confidence that this would work by watching a YouTube video of a PCB etch:
https://www.youtube.com/watch?v=-TPm1eSm2J4
Operations are controlled via EZCAD2 software, which was a little challenging to get started with because the instructions were (mostly) in Chinese. I found this video walk-through helpful.
Things started off a bit slowly because I forgot about fine tuning the focal length (height adjustment). This video provides a good overview of setup, alignment, and focal length adjustment on essentially the same machine we purchased. Jump to 8:11 for focal length adjustment. https://www.youtube.com/watch?v=OR1i_UhYxtE
Laser etched PCB's just got a good writeup on Hackaday too: https://hackaday.com/2021/01/11/laser-blasts-out-high-quality-pcbs/In the static image on the right, the text was etched with 1, 3, and 6 passes of the laser. Each pass removes more material and cuts deeper.
3D Printing Flexible Antennas
The last time I ordered NinjaFlex filament, the blue color I normally order was unavailable. So, I chose Neon. The spool sure didn't LOOK very neon when I received it. It turns out that this variant glows in the dark! The item printed is a conformal metasurface (a chance to use the pink foam below!). The squares are conductive Electrifi filament, and the base layer is NinjaFlex.
Towers of Hanoi or Conformal Antenna Fixtures
Academic version:
Extruded polystyrene circles will be used to hold a conformal antenna at different radii of curvature. Extruded polystyrene was chosen for this work because of its low permittivity (Dk ~= 1.05).
Layman's version:
I need to test a flexible antenna; I will wrap it around the outer edge of these circles. Antennas behave differently when solid objects are nearby. Foam is mostly air, and so it will not change the antenna behavior. I purchased a sheet of 2" thick rigid pink insulation at the hardware store, and I cut it with a hot wire. I previously made circles with a hole saw, but the edges were not very smooth.
Fun version:
I bought a new tool (hot wire cutter). It makes nice smooth cuts through foam. We are going to see who is best at Towers of Hanoi after supper tonight.
LED Driver Board
8x TLC59581 driver chips, capable of up to 4096 pixels (12,288 LEDs)
Based on a TI reference design, this circuit will be used to functionally test and demonstrate custom manufactured LED arrays
Animation is on a 512 pixel array designed and built as a tool for cross-checking and verification of driver electronics
Antenna Bracket
The humble bracket. It's not the star of the show, but it holds everything together and maintains alignment.
This bracket has been adapted to multiple orientations, fixtures, and antennas over the years. It has made appearances in published work like this.
If you'd like to make some for yourself, a dimensional drawing is available at this link.
3D Printing - Radar System Enclosure
Printed on LulzBot Taz 6
100% fill, over 50 hours total print time
Approximately 2.5 kg material, outside dimensions 6"x6"x9"
Piezo Drive w/ Flyback Transformer
Flyback circuit with 10:1 SMT transformer
~100V sinusoidal drive to ceramic piezo from single-cell LiPo power source
Thermal images show temperature of transformer and PCB beneath transformer. Based on these images, more heat spreading measures (copper and vias) were added to both the component side and opposing side of PCB
High peak temperatures (shown) are acceptable due to (very) short duration and duty cycle
Thermal imaging w/ Flir One Pro
RTSpec
Real-time spectroscopy measurements (absorbance, fluorescence)
Fluid exchange prevents saturation
Accelerates search for subtle narrowband effects
Pharmacokinetics, biofilm inhibition, nanoparticles, DNA, and more
Modeling Magnetodynamics - Elmer and COMSOL
The goal is to model a rotating metal disc in the presence of one or more fixed magnets.
To this end, I am learning both Elmer and COMSOL. Both tools are multiphysics finite element method (FEM) solvers.
Present #1: Initial/Kickoff Presentation
Some videos of my Elmer progress:
.zip archive for this demo: Link
Elmer Mesh - make a new mesh (.msh) by importing a STEP file (.stp)
Uniformity of RF fields for Unrestrained Animal Studies
Jared Hansen is exploring the in vivo effects of low-level RF radiation.
I reviewed and verified the use of anechoic pyramidal absorbers in Hansen's experiment.
VNA Calibration and Path Loss Measurement
I worked with a group of undergraduates to measure horn-to-horn path loss vs. frequency for a variety of organic polymers.
We created a series of YouTube videos to capture the calibration and measurement procedure used in this study:
https://www.youtube.com/playlist?list=PL_a8OXrB7lkgUl05pQYuq8GNNNwLfSx1t
The group also created a conference poster based on this work:
https://drive.google.com/file/d/0B3Vo5y7DEGrUR3lnV2p5T3JwMHM/view?usp=sharing
Shockpad
Shockpad is a concept for a rugged Bluetooth accessory which arose from a Startup Weekend I had the pleasure of participating in.
Because I was also enrolled in a Systems Engineering MS program at the time, I continued to explore several technical aspects of this product beyond the weekend.
You can find my work over on my blog; relevant posts are dated October-December 2015. Strikecity blog
