Fig. 6: Locomotion analysis of DEMES crawler.

a Schematic and digital images of the working principle of two-anchor crawling locomotion of a DEMES crawler. When a voltage (V) is applied, the crawler flattens and extends to give a vertical (Δy) and lateral displacement (Δx). After the voltage is removed, asymmetric friction from the bent front PET leg enables the crawler to crawl forward. b Schematic and digital image of the usage of NIR light as a secondary control to increase the stride of the crawler, with larger Δx and Δy. c Δy and Δx of two-anchor crawling locomotion as a function of time. First, the crawler was driven by an electric field of 35 V μm⁻¹ at 1 Hz. After which, NIR light (0.4 W cm⁻²) was applied continuously while the crawler was driven by the same electric field. When NIR light was applied, the enhanced stride led to a larger distance traveled. d Digital image of the crawler driven by 35 V μm⁻¹ at 1 Hz to crawl under a low tunnel (width 50 mm × length 5 mm × height 18 mm). When the crawler comes into contact with the tunnel (40 s), it first attempts to adapt its body to crawl under the tunnel based on its soft and flexible nature (40–70 s). Due to the larger height of the crawler, it eventually gets stuck in the tunnel. When NIR light is applied, the crawler is able to release itself to crawl through the tunnel due to a larger vertical displacement generated during crawling.