Subfab Drain Sentry, MakeOHI/O 2026 — Intel Challenge

By Sahil Gandhi, Aneesh Jonnala, and Samanyu Vyakaranam

Code written by Aneesh Jonnala

Real-time semiconductor wastewater classification on a Raspberry Pi Pico 2W. Measures TDS and temperature, applies thermal compensation, and routes water to reuse, filtration, or brine management using SEMI F63 thresholds.

Routing Logic

LED	TDS	Temp	Action
🔵 Solid	< 1 ppm	≤ 35°C	Direct UPW reuse
🟢 Slow blink	1–500 ppm	≤ 35°C	RO/DI filtration
🔴 Fast blink	> 500 ppm	> 35°C	Brine / discard

Hardware

• Raspberry Pi Pico 2W
• DFRobot SEN0244 TDS → GP28
• DS18B20 temperature → GP27
• RGB LEDs → GP6, GP12, GP10

Math

coeff  = 1.0 + 0.02 × (T − 25)
V_comp = V_raw / coeff
TDS    = (133.42V³ − 255.86V² + 857.39V) × 0.5

Setup

1. Add Pico 2W board support in Arduino IDE
2. Install OneWire and DallasTemperature
3. Flash sketch_final/sketch_final.ino
4. Serial monitor at 115200 baud