Logic-enabled textiles

Abstract

Textiles hold great promise as a soft yet durable material for building comfortable robotic wearables and assistive devices at low cost. Nevertheless, the development of smart wearables composed entirely of textiles has been hindered by the lack of a viable sheet-based logic architecture that can be implemented using conventional fabric materials and textile manufacturing processes. Here, we develop a fully textile platform for embedding pneumatic digital logic in wearable devices. Our logic-enabled textiles support combinational and sequential logic functions, onboard memory storage, user interaction, and direct interfacing with pneumatic actuators. In addition, they are designed to be lightweight, easily integrable into regular clothing, made using scalable fabrication techniques, and durable enough to withstand everyday use. We demonstrate a textile computer capable of input-driven digital logic for controlling untethered wearable robots that assist users with functional limitations. Our logic platform will facilitate the emergence of future wearables powered by embedded fluidic logic that fully leverage the innate advantages of their textile construction.

Keywords: assistive devices; fluidic logic; information storage; logic gates; wearable robots.

Fig. 1.

Pneumatic logic built from textile inverters. (A) Schematic overview of a wearable assistive robot that integrates textile actuators, input devices, and control units (built from inverters). (B) Internal layout of the textile inverter. (C) External features of the device after assembly. (D) Operation of the kink valve, showing the kink angle ϕ. The flow channel ABCD deforms into the kinked configuration A′B′C′D′ when the input pouch is inflated. (E) Equivalent pneumatic circuit of the inverter, consisting of a normally open fluidic relay (kink valve) coupled to a pull-down resistor. (F) The inverter folded in half and then into quarters to show its flexibility. (G) Experimental input and output pressure traces, illustrating the switching action of the inverter and its operation as a NOT gate. (H) Experimentally measured switching hysteresis of a typical inverter device, showing the forward (P₊) and reverse (P_–) threshold pressures.

Fig. 2.

Architecture of the sheet-based pneumatic kink valve. (A) The kink angle ϕ as a function of the pouch overlap s; the red curve represents the theoretical angle predicted by Eq. 1, and the data markers denote experimentally measured angles (averaged over at least three replicate measurements). (B–E) Representative cross sections of offset pouches of increasing overlap, displaying the internal geometry of the middle layer. The experimentally measured kink angles plotted in A were inferred from these images by fitting circles to the pouch walls, as shown with an overlay in C. (E) Shows overlapping pouches with s = 0.88, for which buckling of the channel resulted in a smooth profile devoid of kinks.

Fig. 3.

Modular logic circuits assembled from two textile inverter units. (A) A binary NAND gate, along with its logic circuit, truth table, and experimentally measured pressure traces. (B) An SR latch, along with its logic circuit, state-transition table, and experimentally measured pressure traces for various state-input combinations. The combination S = R = 1 is not a valid input for operating the latch. Full pneumatic circuit diagrams for all modular logic gates are included in SI Appendix, Fig. S17.

Fig. 4.

Textile ICs for user-driven logic control. (A) Actuation mechanism of the pushbutton valve. (B) Internal layout of the textile controller, showing channels, pouches, and vias that enable latch operation in response to user input. A complete pneumatic circuit diagram of the controller is included in SI Appendix, Fig. S17. (C) Photograph of the heat-sealed textile IC with integrated resistors and pushbuttons. (D) Active-low output generated by a single pushbutton in response to finger presses by the user. (E) Experimental traces showing user-applied force on the controller pushbuttons and the corresponding change in the latch output Q.

Fig. 5.

Controlling wearable assistive robots using textile logic. (A) The textile IC configured for controlling a wearable assistive robot. The controller is mounted on the user’s garment using hook and loop fasteners and supplied from a portable gas cartridge. (B) User-driven operation of the textile-based arm-lift actuator. (C) User-driven operation of the textile-based hood actuator. The plot on the right shows an increase in measured skin temperature upon donning the hood in light breeze.

Fig. 6.

Accelerated wear and durability tests on the textile inverter. (A) Cyclical switching of the textile inverter at 50-kPa supply pressure. (B) The inverter being folded repeatedly in half on a bespoke test rig. (C) Experimental pressure traces confirming normal functioning of the inverter after 20,000 on-off cycles and one million flex cycles. (D) Laundering the inverter in a washing machine. (E) The inverter being run over with a pickup truck to simulate rough handling. (F) Experimental pressure traces confirming normal functioning of the inverter after 20 wash cycles and being run over 5 times (i.e., 10 passes of the truck wheels).