The plasma feature

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The archive

The complete record of the plasma platform — the walkthrough, every plate, both raw clips, and the reviewed papers. The edited version of this is the feature; this is everything.

Assembled from the lab folder as handed over. The plasma feature carries the case for the machine; this carries the rest.

A The walkthrough

Six and a half minutes at the bench, narrated. The one place the work is explained rather than shown. Nothing downloads until you press play.

Film A full walk through the platform — the arm, the discharge, the diagnostics, and what each part is for. Recorded in one take.

B The system working

The arm holding the torch at standoff over a tissue phantom, and the run that shows the standoff is what stays constant, not the position.

Fig. 1 The full twenty-six second treatment run, untrimmed. The torch is under path control; the gap between its tip and the phantom is the entire problem this machine exists to solve.
Fig. 2 Treating a wound phantom — full-resolution frame from the run. The glass tube is the discharge electrode.
Fig. 3 Six frames across the run: the torch head displaces rather than dwelling, which turns a point dose into a treated area.
Fig. 4 The full bench mid-run: CAD open on the laptop, oscilloscope on the discharge, phantom under the torch, posters behind.

C Electronics and mechanics

One board, six axes, a set of printed links, and the board project and stress analysis behind them.

Fig. 5 The control board: six TMC5160 Pro drivers under the red heatsinks, a Teensy 4.1, bulk power, encoder inputs, hardware e-stop.
Fig. 5a The EasyEDA layout for that board — the TMC5160T Pro carrier, rev 1. Designed and routed in-house; an earlier revision of the controller was done in KiCad.
Fig. 6 The assembled arm alongside the board, wired and powered. Printed PETG links. Reduction varies per joint: ~10 Nm at the shoulder through a 20:1 planetary, 4:1 belts at the wrist. 1 kg near the base, 0.5 kg across the full workspace.
Fig. 7 Every joint module, stepper, and the driver board laid out. Every structural part was printed rather than purchased.
Fig. 8 A single joint: printed housing, integrated ring gear, encoder bore, and ventilation for continuous duty.
Fig. 9 The mechanical design: belt-driven joint, bearing stacks, ribbed base, fastener stack-up.
Fig. 9a Static von Mises stress analysis on the structure — the FEA that says the printed links hold the load before one is cut.

D Plasma and diagnostics

Knowing what the discharge is doing, which means measuring it and not assuming it.

Fig. 10 Dielectric barrier discharge in the chamber. The violet emission is the excited nitrogen and oxygen species that do the antimicrobial work.
Fig. 11 The torch firing in a darkened lab with an Ocean Optics HR4C4660 acquiring on the laptop, process gas behind.
Fig. 12 The full diagnostic bench: CTP-2000K generator with live voltage and current, oscilloscope, spectrometer laptop, gas supply.
Fig. 13 The chamber on its own — glass tube, internal ring electrodes, gas feed, HV leads.

E Biology and validation

The other side of the dose: what the plasma does to a bacterial load, characterised in culture.

Fig. 14 Shaker incubator with culture flasks, from the E. coli work characterising plasma dose against bacterial load.
Fig. 15 Running library prep and sequencing at IntelliScience.
Fig. 16 The Teensy 4.1 that runs motion control. The 40 °C thermal cutoff runs host-side in Python at 10 Hz, not in firmware.

F What it looked like before

Kept in on purpose. A portfolio that only shows the finished machine is a claim about taste, not about work.

Fig. 17 The arm moving before the control loop was tuned: twitchy, overshooting, unusable. The full nineteen seconds. Everything in group C exists because of this.
Fig. 18 And where it started — red printed arm, drivers loose on a breadboard, jumper wires. Every part of this was replaced.

G The papers

The reviewed record, as filed. Open in the browser or download.

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