U.S. Department of Agriculture
Electrical Engineer (Clinic)
August – December 2024 · Harvey Mudd Engineering Clinic, with Auburn University
Developed a next-generation Electrical Penetration Graph (EPG) instrument for studying insect feeding. Final units were validated on three insect species across four lab visits.
Highlights
- Developed four revisions of mixed-signal PCBs in KiCad for low-level biological signal amplification and digitally controlled AC/DC excitation.
- Owned component selection, LTspice simulation, board bring-up and rework.
- Designed a validator PCB for testing prototype analog boards, which the client adopted as a standardized test procedure.
- Final units produced waveforms entomologists could recognize on 3 insect species across 4 lab visits.
The problem
An Electrical Penetration Graph places an insect and a plant into a tiny electrical circuit. As the insect feeds, the signal changes in ways entomologists recognize as specific behaviors. The signals are very small, so the instrument needs a clean, high-gain front end and a carefully controlled excitation source. Our sponsors at the USDA and Auburn University wanted a next-generation design.
What I built
I developed four revisions of the mixed-signal PCBs: an amplifier chain for low-level biological signals, plus digitally controlled AC and DC excitation. For each revision I picked the components, simulated the analog path in LTspice, laid out the board in KiCad, and then brought it up and reworked it on the bench.
To make testing repeatable, I also designed a validator PCB that lets you check a prototype analog board against known inputs. The client adopted it as part of their standardized test procedure.
Results
The final units were validated on three insect species over four lab visits and produced waveforms the entomologists could recognize.