Saturday, May 8, 2021

The best projects from 10 years of Applied Science

 Liquid oxygen BBQ -

Fondant cake making -

Scanning Electron Microscope -

Transcranial magnetic Stimulation -

Supercritical CO2 chamber -

LED in a contact lens -

Pop Rocks candy -

X-Ray backscatter -

X-Ray CT -

Cookie Perfection Machine -

LCD - and

Vinyl LP in electron microscope -

Silicon etching rugate optical filters -

Monday, February 22, 2021

Measuring human digestive efficiency vs. a flame

 "200 Calories" on a nutrition label doesn't describe the total flammable caloric content. I explore the differences between digestible and flammable calories using a homemade calorimeter with glass windows.

Pressure sensor: Schedule 160 pipe on McMaster: 32 ga nichrome wire: Power supply (used for ignition wire): Keithley 6.5 digit multimeter: Tek MSO 4 series oscilloscope: Soylent: Support Applied Science on Patreon:

Sunday, January 17, 2021

Prototyping with Applied Science: Design and build a bite sensor

Join me in brainstorming and building a bite force sensor that allows paraplegic musicians to smoothly control an expression pedal. This video will include construction tips and tricks, methods, material selection, and a little design philosophy.

Tiny linear potentiometer used in final design: Spring-loaded linear potentiometer: Sil-Poxy for bonding silicone rubber to itself and other materials: Sorta Clear 40 - Platinum-cure silicone molding: Light-cure 3311 adhesive: (expensive, but this tube will last a long time) Blue lasers on eBay "5mW" *wink* Braided shield, highly flexible, 4-conductor cable: Fabric reinforced silicone sheet: Mechanical CAD on github: Support Applied Science on Patreon:

Sunday, November 15, 2020

Etching silicon wafers to make colorful Rugate optical filters (porous silicon)

Passing an electrical current through a silicon wafer in a special acid etchant will create a porous layer with a variable index of refraction. I describe how this process works, and how the Fourier transform relates filter design to electrical etch waveform and resulting spectral response.

Notes: 1. The Rugate filters look especially good in polarized light because the reflection from the silicon wafer is reduced, but the reflection from the filter remains strong. I noticed this while holding the wafer in front of my computer monitor. Later, when showing it to friends, the color intensity was poor. Their monitor must have been horizontally polarized, so holding the wafer low, and tilting it upward didn't work! Some monitors are horizontally polarized, and some are vertical. 2. The magnet used to hold down the PTFE cup to the wafer may have a very slight impact on the etch process. The dramatic shift in filter performance at the periphery is due to O-ring restricting the conductive etchant to a sharp edge, creating an electrical field concentration. Outstanding visual Fourier series tutorial: LR-1 spectrometer: p-type wafers on eBay. (You have to hunt around and check the photos for info on the label attached to the box of wafers. Be sure to get wafers less than 0.01 ohm-cm) eg n-type wafers are photosensitive during the etch process. Online graphing calculator page from this video: Original Desmos page that I used: Code for Keithley 2450 control and waveform generation: Fourier transform to understand optical coatings: Porous silicon refs:

Sunday, September 20, 2020

Shooting an electron beam through air

 A special 100nm thick window allows 25 KeV electrons to pass from a vacuum tube to the atmosphere where they hit a fluorescent screen -- a CRT in air!

Shielded GoPro goes through a powerful electron beam: More powerful amateur electron beam in air: Deep technical resource on dielectric charging via electron bombardment: Tons of information on industrial e-beam processing: KF25 to glass tube quick adapter: 100nm silicon nitride windows: More windows: Tritium light sources (eBay removed most): E-beam crosslinking: KF25 cross $18 on Amazon: Lightbulb sockets: Hysol 1C: Applied Science on Patreon: