prox-sense

prox-sense is a series of printed circuit board (PCB) designs for designed to bring robust and discreet capacitive proximity and touch sensing to artists and makers.

Video demonstration and poster: Hidden Touch: Open Source Sensors for New Interaction

This repository contains the KiCAD schematics, boards, and Gerber files required to produce the sensing boards. License notice below.

Premise

Existing systems for creating interactive experiences:

• Expensive
• Can be difficult to use or understand
• Limited or nonexistent proximity detection (existing capacitive options)
• Dense arrangements of proximity sensors may not function (existing capacitive options)
• Connectivity options do not scale up to large systems of sensors
• Equivalent/alternative optical systems are intrusive, expensive, or predictable (cameras, vision systems)
• Require large amounts of processing or setup
• Existing tactile systems are predictable (buttons, knobs, touchscreens, etc.)

prox-sense promotes discoverable and new interactions:

• Inexpensive
• Focus on proximity detection
• Proximity through solid and opaque objects (sensors can be entirely hidden)
• Directional proximity detection options allow for dense arrangements
• Interaction is led by the objects the sensors are hidden in and the resulting interactions, not the sensors and sensor limitations
• Small sensors allow for small detection areas and objects
• Simple connectivity scales up to large systems without limiting the maximum number of easily-connected sensors
• Open source and free to produce

Boards

Currently all boards are based around the Microchip MTCH105

• Simple GPIO interface for detection and sensitivity adjustment. The standard logic output can be used directly with microcontrollers, logic circuits, transistors, muxes, and port expanders
• Rejects liquids and other uncertain signal sources
• Supports guard reference signal for solid interference mitigation
• All boards currently use the same schematic but vary the copper/trace layout to achieve different detection patterns

Directional board

• Detects proximity and touch only directly in front of the sensors
• Rejects rear and off-axis (side) detection using guard signal
• Guard signal on edge allows for close-packing of sensors

Omnidirectional board

• Detects proximity and touch from all directions
• Guard signal on edge allows for close-packing of sensors

License Notice

Copyright Perry Naseck 2022.

This source describes Open Hardware and is licensed under the CERN-OHL-S v2.

You may redistribute and modify this source and make products using it under the terms of the CERN-OHL-S v2 (https://ohwr.org/cern_ohl_s_v2.txt).

This source is distributed WITHOUT ANY EXPRESS OR IMPLIED WARRANTY, INCLUDING OF MERCHANTABILITY, SATISFACTORY QUALITY AND FITNESS FOR A PARTICULAR PURPOSE. Please see the CERN-OHL-S v2 for applicable conditions.

Source location: https://github.com/DaAwesomeP/prox-sense

As per CERN-OHL-S v2 section 4, should You produce hardware based on this source, You must where practicable maintain the Source Location visible on the external case of the prox-sense or other products you make using this source.