Fabric logic library: A framework for integrated mechanical circuitry in smart pneumatic fabrics

Abstract

This paper introduces a framework for a pneumatic logic library to support integrated mechanical circuitry within Smart Pneumatic Fabrics. Smart Pneumatic Fabrics consist of multiple layers, each engineered with distinct patterning to form pneumatic logic components—such as porous cotton resistors, laminated channels with cross-layer vias, pouch capacitors, and kink-threshold channels. For each basic component in the library, logic models are developed using first principles with key parameters identified experimentally: (1) porous resistors are described by Darcy–Forchheimer flow behavior, (2) channel–via resistance is characterized by weak length and strong width dependence, (3) pouch capacitor response is mapped via a three-regime pressure–mass relationship, integrating pressure–volume measurements with the ideal gas law, and (4) kink-valve threshold channels exhibit linearly varying pressure thresholds with inlet pressure and quantifiable hysteresis. The library’s modularity enables the synthesis of compound components for complex pneumatic circuits. Demonstrating this approach, a three-stage ring oscillator using pneumatic transistor compound components was designed with Simscape™, fabricated via a masked heat-sealing process, and validated experimentally, confirming predictable oscillator frequency with in-situ adjustable oscillation frequency. This library framework advances the systematic creation and integration of sophisticated, electronics-free control logic in Smart Pneumatic Fabrics for next-generation wearables and soft robotic systems.