How I Built an AI Assistant on My Wrist for Under $15 Using ESP32 + Claude API

The Idea What if you could have Claude AI on your wrist — not on a $400 Apple Watch, but on a $4 microcontroller? I built exactly that: a wrist-mounted AI assistant using an ESP32-S3, a tiny OLED screen, a microphone, and the Claude API. Total parts cost: under $15 USD. It can: Answer questions via text or voice Translate between 5 languages in real-time Monitor your heart rate and give health insights Run any custom AI behavior via system prompts The Architecture The key insight: Claude doesn't run on the chip. The ESP32-S3 handles sensors, WiFi, and display. All AI processing happens in the cloud via API. You press button → ESP32 records audio ↓ Audio → Google Speech-to-Text API → text ↓ Text → Claude API → response ↓ Response → OLED screen on your wrist End-to-end latency: 2-5 seconds. Hardware (Total ~$15) Part Price ESP32-S3 DevKitC $4-6 SSD1306 0.96" OLED $1.5-2.5 INMP441 I2S Microphone $1.5-2 3.7V LiPo Battery + TP4056 $2 Dupont wires + breadboard $1 The Core Code Here's the sim