Write on paper.
See it digitally.
A smart pen that streams real-time sensor data to a host, where deep learning translates your physical writing into digital strokes on any canvas app.
A smart pen that streams real-time sensor data to a host, where deep learning translates your physical writing into digital strokes on any canvas app.
No computation on the pen. All intelligence lives on the host.
Use the 3D Pen like any normal gel pen. Write, draw, or sketch on real paper.
Pressure, dual IMUs, and capacitive touch sensors stream data at 8kHz wirelessly.
A deep learning model on the host translates raw sensor streams into 2D stroke coordinates in real time.
The pen registers as an OS-level input device. Your strokes appear in any canvas app.
All electronics fit in a 2.75mm annular gap between the refill and the outer shell.
0 – 15mm
Removable threaded nib (M10x0.75) in black POM. Unscrews to insert standard gel refills.
15 – 55mm
FSR 400 Short pressure sensor (40mm zone) plus IMU #1 (ICM-42688-P) for nib-end motion tracking.
55 – 80mm
Azoteq IQS263 capacitive touch slider with 4 electrode pads. ADXL367 wake controller for power management.
80 – 110mm
nRF52840 (ARM Cortex-M4F) with integrated 2.4GHz radio. PCB IFA antenna for wireless streaming.
110 – 135mm
10180 Li-ion battery (100mAh), BQ51003 Qi receiver, BQ25100 charger, MAX17048 fuel gauge, IMU #2.
135 – 150mm
Sealed end cap with 9mm Qi receiver coil and ferrite shield. Debug flex tail exits before seal.
Exploded view: 12 components from nib cone to end cap
| Parameter | Value |
|---|---|
| Dimensions | 150mm L × 11.5mm D |
| Weight | 20 – 28g (polycarbonate shell) |
| Refill | Standard gel pen (110mm × 6mm, Pilot G2 compatible) |
| MCU | nRF52840 — ARM Cortex-M4F, 256KB RAM, 1MB flash |
| IMU | 2× TDK ICM-42688-P (6-axis, 32kHz max ODR) |
| Pressure Sensor | Interlink FSR 400 Short (0.3mm, 5.6mm active area) |
| Touch | Azoteq IQS263 capacitive slider + proximity |
| Wireless | Nordic ESB at 2Mbps (BLE secondary for config) |
| Data throughput | 6ch × 8kHz × 16-bit = 768kbps |
| Battery | 10180 Li-ion, 100mAh, 8–14+ hours active |
| Charging | Wireless (Qi-style) via cradle |
| PCB | 2-layer flex polyimide, helical wrap, 230mm × 10mm |
| Firmware | Zephyr RTOS via nRF Connect SDK |
| Host inference | ONNX Runtime, <10ms per window |
| HID | OS-level digitizer pen (Usage Page 0x0D) |
| OS Support | Windows, macOS, Linux |
AI-generated concept renders and the original hand-drawn sketch.
This is an independent open-source hardware project. Your support funds components, PCB fabrication, and prototyping.