Test & Validation — Ege Ozemek

Lightbox — Control Characterization

I swept the finished lightbox against both of its control inputs and measured its timing loop on a scope, then fitted the results.

A Tektronix TBS 1102B oscilloscope on a lab bench displaying a clean square wave across the screen at 20 V per division and 100 ms per division. — Switching output on the bench scope (Tektronix TBS 1102B), 100 ms/div.

The same oscilloscope with time cursors placed on the waveform: the on-screen readout shows a measured period of 135.2 ms, a 50.0 ms cursor delta, 20.00 Hz, and a 3.20 V amplitude delta. — Time cursors placed on the output — measured period 135.2 ms.

Measured on the bench oscilloscope
Measurement	Sweep	Result
Eye brightness duty cycle vs control voltage	5 points · 0.862–3.3 V → 16.7–65.4 %	R² = 0.99994
Blink rate vs control voltage	5 points · 0–3.3 V → 5.00–7.35 Hz	R² = 0.974
Heartbeat period	10 trials	1000 ms, 10/10

ToolsOscilloscope · Curve fitting

Pacemaker — Strength–Duration Curve

Threshold current measured against stimulus duration on frog ventricular myocardium, then fitted. The fit set the pulse width the pacemaker firmware uses.

Swept stimulus duration from 1 to 500 ms, recording the threshold current that evoked a visible ventricular contraction at each point.
Nonlinear least-squares fit to the hyperbolic form I(d) = b(1 + c/d): rheobase b = 45.8 µA, chronaxie c = 10.3 ms.
Firmware pulse width was then set to twice the measured chronaxie, taken from this fit.

Strength–duration curve for frog myocardium: measured threshold current in microamps plotted against stimulus duration in milliseconds, falling steeply from about 520 µA at the shortest durations and flattening toward the rheobase. A hyperbolic fit runs through the points, with dotted lines marking a rheobase of 45.8 µA and a chronaxie of 10.3 ms. — Measured points with the hyperbolic fit — rheobase 45.8 µA, chronaxie 10.3 ms.

ToolsCurve fitting · Threshold measurement · Electrophysiology · Python

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Diagnostic Ultrasound — Acquisition & Measurement

Scanning a training phantom on a clinical system: setting up the preset, optimizing the image, and placing measurement calipers.

Siemens Healthineers ACUSON P500, CH5-2 probe on the Early OB preset: MI 1.40, TIS/TIB 0.3, 75 dB dynamic range, tissue harmonics at 3.6 MHz, 11 cm depth.
Distance caliper placed across the target: D1 = 79.2 mm.
Acquired on a training phantom in a teaching lab, not on a patient.

An ACUSON P500 ultrasound screen at Duke BME Teaching Labs showing a B-mode image of a training phantom on the Early OB preset, with acquisition parameters listed down the left edge and a distance measurement reading D1 = 79.2 mm. — ACUSON P500, Early OB preset — distance caliper reading D1 = 79.2 mm.

ToolsUltrasound · Clinical imaging systems