A materials scientist needed help with the electronics for a device that
could detect and identify several operational parameters of phosphorescent
materials. If these materials, which are normally invisible, are illuminated by
a strong light, they emit light for some time after the illumination is removed.
Similar materials are applied to the inside of your television tube to produce
the light that creates the pictures you see. My client's company, having found a
supplier of the materials, was interested in using them in various security
applications.
First, we met with the suppliers and a consultant of theirs who had designed
some detection circuitry. Then I built some simple detection circuitry so we
could characterize various grades of the material. We also obtained a prototype
detector from the supplier's consultant and found it close to meeting our
functional requirements.
My client's company wanted to develop a product that had more consumer appeal
than the prototype's boxy 'calculator' look, so we worked with an industrial
designer and a mechanical designer to engineer a slim, hand-held package that
would fit comfortably in a shirt pocket. I redesigned portions of the
electronics and created a schematic. The product, powered by three AAA
batteries, included a PIC microprocessor, a one-button user interface, an
indicator LED, one high power illumination LED, and a super high gain
photo-detection front-end. I wrote the firmware in assembly code, and tested a
prototype.
Then came the difficult part. We, that is, the mechanical designers and I,
had to negotiate our way through several iterations of printed circuit board
design, parts placement, and mechanical design until we found a package that
provided adequate volume and form for the electronics, yet still satisfied the
client's desire for a small and comfortable product. I manufactured 25-30
prototypes, the industrial designer made the enclosures, and I performed the
final assembly.
Later, I followed up this project with some research into some advanced
algorithms for analyzing the phosphorescent data and identifying the materials.
This project showcases my experience with working with other scientists,
engineers, and designers to accomplish a multi-disciplinary task. It also
highlights my experience in low-noise analog design, PIC microcontroller
development, ultra-low power design, software design, assembly language
programming, controls, optics, and electro-optical detection.
