Fig. 3: Soft-actuator-integrated nerve cuff electrodes.

a, Examples of the proposed nerve cuffs with targeted shape transformation paths and bending curvatures that are adaptive to nerve dimensions and surgery needs, realized through the prescribed arrangement of actuator elements. b, Optical micrographs of a flat cuff device that can be bent into curls with a bending radius of 170 µm. The cuff integrates two recording electrodes at the left and right edges, with aligned micro-striped actuators in between. c, Photograph series showing the swift actuation following a helical path in 2.1 s, enabled via the design of asymmetrically patterned actuating elements. The black-coloured strips are PPy(DBS)/Au. The applied voltage is 0.6 V. d, Exploded device render showing each layer of the robotic thin-film nerve cuffs. Here, for simplicity, the depiction excludes the conducting Au tracks within the Au layer. e, Photograph of the device bonded to a flat flexible cable (FFC) connector showing the overall structure. The optical micrographs on the right show a detailed design of the implanted interfacing section. f, Stress–strain curves for thin-film devices composed of 1.95 μm PaC, 10 nm Ti, 100 nm Au and 6.70 μm PPy(DBS). Five samples were tested. The photograph in the inset shows a microfabricated nerve cuff conforming to a finger, demonstrating the high conformability of the device. g, Photograph sequence showing a nerve cuff wrapping on a 1.4 mm nerve phantom in PBS. A simplified cuff with three microelectrodes was used for this demonstration. h, Comparison of the radius of the helical structures under different voltages. Devices with varied thicknesses of PaC and PPy were measured. The bending radius measured for the 3 μm PaC and 4 μm PPy(DBS) sample at 0 V exceeds 5 mm, which surpasses our plotting scope and thus is omitted from this plot. Data are shown as mean ± s.d. (n = 3). Scale bars, 1 mm (b); 5 mm (c); 5 mm, 1 mm, 50 µm (e (from left to right)); 1 cm (f); 2 mm (g).

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