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Parallax Insider News

Propeller 1 Multicore Microcontroller Tests N95 Alternative Face Mask

  • By: Ken Gracey Published: 20 April, 2020 0 comments

Dear Community,

Paul Voss, a Professor from Smith College and an inventive engineer, has two interesting applications using the Propeller 1.  The first is a timely test fixture he made for the MITMedia Labs MASK Project: N95 Alternative Face Mask project. The second is something we'd all like to have when the COVID-19 pandemic has eased - the SpecCNC AeroForm Complete CNC Hotwire Foamcutter. If you've ever built a model plane from balsa wood and Monokote or spent days browsing the Tower Hobbies catalog while considering their "layaway plan" then this load-and-cut machine would've been beyond your wildest dreams!

Propeller 1 Test Fixture for the MASKproject: N95 Alternative

 N95 Alternative mask prototype with removable filter media

The MIT Media Lab MASKproject was formed by a group of inspired engineers who are setting out to save more lives by making an alternative N95 face mask. Their goal is to make a reusable face mask which is mass manufacturable with rapid deployment, open hardware, sterilizable, modular, and filter-media agnostic that aims to hit the N95 efficacy criteria.

Parallax customer and Smith College Professor Paul Voss is a contributor to the project with a test fixture, based on the Propeller 1 Multicore Microcontroller. His test rig measures respirator filter performance (flow, resistance, particle penetration). Paul indicates that the project is moving fast with prototype injection-molded parts already coming off the line.  His text fixture accepts filters into this cardboard/plywood structure where measurements are taken during air movement through the filters (which are embedded in a PVC tube from the hardware store).

 N95 Alternative

I asked Paul about how he produced the circuit board so quickly. The circuit board was actually created for his Aerial Design Course at Smith College and it uses a Propeller 1, Analog Devices 16-bit 6-channel A/D, two Freescale pressure sensors, 3.3 and 5V reference voltages, and numerous pins for servos, LCD, Ping))) Ultrasonic Sensor and a 9 degree-of-freedom gyroscope/accelerometer/magnetometer. The project was coded in Spin and the circuit board was quickly adapted as the test fixture for MASKproject.

The values shown on the LCD are:

  • PA = Ambient pressure [Pa]
  • DP = Differential pressure across filter material in the test section [Pa]
  • HT = Height of variable-volume tube measured by Parallax Ping))) [mm]
  • DH = Change in height over five-second period [mm]
  • QT = Volumetric flow rate through the filter test section [LPM=liters per minute]
  • VT = Velocity of air through the test section [mm/sec]
  • QM = Volumetric flow rate through the prototype respirator assuming same velocity [LPM] 

The efforts of Matt Carney, Paul Voss and the MASKproject team are incredible and recognized!

LCD readout from Propeller module gathered data

SpecCNC AeroForm: Complete CNC Hotwire Foam Cutter Based on Propeller 1

 Complete CNC Hotwire Foam Cutter Based on Propeller 1

This is another inspiring Propeller 1 Multicore Microcontroller project from Paul Voss - one which makes us look forward to summer, hobbies and outdoor activities. The AeroForm is a complete CNC hotwire foamcutter that brings professional aeronautics capability to schools, businesses, clubs, and home workshops. We have one of Paul's SpecCNC AeroForm cutters in the Parallax office in Rocklin, California and I had to put it in a box and pack it up because it was so much fun. Some details:

  •  Ready-to-run machine assembles in a few simple steps
  •  Simple and versatile push-button operation - no computer or special software required
  •  Rapidly make wings, stabilizers, and other aircraft parts from inexpensive foam board
  •  Set chord, taper, sweep, washout, and even add custom spar channels
  •  Choose from dozens of performance airfoils or use your own coordinates on the SD card
  •  Use the miter function to cut accurate angles for dihedrals, winglets, and assembly
  •  Use the manual lathe function to cut approximate nose cones
  •  Set cutter offset, feedrate, and heater power for different foam types (EPS, XPS, EPP)
  •  Finished parts up to 24" x 12" x 4" are easily assembled into much larger models
  •  High-quality made in USA from solid wood, stainless hardware, and custom electronics

And you may be asking: can I buy one of these? Yes! Paul's SpecCNC AeroForm web site provides purchasing details. Be patient with him if you're going to make a request - not only is he busy with the MASKproject above, he's a full-time professor and must sort through the inquiries to make sure they're within his production and support capabilities. It's quite common for already-productive engineers to limit their ability to meet demand they can handle.    

Foam glider parts cut with the AeroForm

After you cut out the parts, you can simply glue them together and make an incredible glider. Below is a picture of the Stratolaunch, an unpowered glider. With some glue and wooden dowels, the foam can quickly be attached to a fuselage.

Glider made from AeroForm cut parts

Paul has also created R/C versions flown with brushless motors and LiPo power packs.

Let these projects be an inspiration for ideas of your own!


Ken Gracey and the Parallax Team