2017 · ODE Lab · Harvey Mudd research
Research in the Open Devices Engineering (ODE) Lab building low-cost, open-source instruments for semiconductor fabrication. The main project was a network analyzer that cost about $15.
Measuring the resonant frequency of a MEMS cantilever usually needs a benchtop network analyzer, which is expensive and out of reach for a low-cost lab-on-a-chip system. The lab built open-source instruments that anyone could make, so the goal was to do the same measurement for around $15.
Designed, built, and tested a PCB that generates and measures sine waves from 10 kHz to 20 MHz. I wrote the embedded C to drive a direct digital synthesis (DDS) chip from an STM32 over SPI and set up the microcontroller. Everything used an open-source toolchain, so the design is easy to reproduce.
Explored time-interleaving to raise the effective sampling rate without paying for expensive high-speed ADCs.
I also built other open hardware for the lab: an Arduino-like STM32 board, an LED-matrix PCB for a spectrometer prototype, a clip-on JTAG connector for faster programming, and Hall-effect sensor testing for precise RPM control on a spin-coater.
A working network analyzer for about $15 that could find a cantilever’s resonant frequency, making the lab-on-a-chip system cheaper to build and reproduce.