- Participants designed a low-cost impedance-spectroscopy platform for cell or nucleic-acid analysis: an AD9834 DDS (0–75 MHz) feeds a simple peak-detector/phase-discriminator circuit read by an AVR to generate Bode plots without a high-speed ADC, and they compared this to the integrated AD5933 chip (0–100 kHz) and the higher-end AD9958 (500 MHz dual-output).  
- A DIY flow-cytometry thread explored slowing microfluidic flow and imaging with a high-frame-rate camera, then pivoted to using a hemocytometer as a continuous yeast counter; nmz787_i suggested OD600, impedance spectroscopy, and Coulter counters as alternatives, while ParahSailin_ warned that yeast clogs commercial cytometers.  
- The group shared a 1-million-lumen, 500-ns LED flash (180 A, 2.8 kW for 0.5 µs) for ultra-high-speed photography and used moiré patterns and holographic microscopes to illustrate how nonlinear spatial operations mirror RF heterodyning, recommending GNU Radio Companion and a $10 RTL-SDR dongle for hands-on DSP learning.  
- A $200 USB thermal camera (206×156 px, 9 Hz, 8–14 µm) was highlighted as a dramatic price drop, and vanadium-dioxide VO₂ films (68 °C phase-change, 100 fs switching) were cited as ultra-fast optical/IR modulators for future DIY sensors.  
- Mechanisms of transcranial direct-current stimulation (tDCS) were dissected: a “bimodal polarization” model explains immediate neuronal effects, but long-term after-effects remain unexplained; links to PubMed review PMID 22949089 and ultrasound neuromodulation papers were provided, contrasting tDCS with invasive $26 k deep-brain stimulation.