Fig. 3: Adaptive gripper and robotic skin based on microbubble-array artificial muscles.

a, Time-lapse sequence showing a live zebrafish larva grasped by a soft gripper composed of multiple artificial-muscle petals (10 mm × 0.7 mm × 80 µm), each incorporating microbubble arrays (12 µm in diameter × 50 µm in depth). Inset: magnified view of the larva. b, Rotation of an almond by a conformable microbubble-array robotic skin (12 μm × 50 μm). c, Deformation of a blade of grass by the same robotic skin, showing self-attachment and actuation. Inset: magnified view of the microbubble array. d, Conformal attachment of a green fluorescently labelled cardiac patch (30 mm × 10 mm × 80 μm) to the epicardial surface of an ex vivo porcine heart. e, Experimental set-up showing an excised porcine bladder with an ultrasound transducer positioned approximately 5 cm from the left side and an endoscope inserted for internal visualization. f, Time-lapse endoscopic images showing the encapsulated artificial muscle inside the bladder, its release at approximately 3–5 min and conformal attachment to the inner wall at 4.2 min under ultrasound activation. Scale bars, 5 mm (a–c), 1 cm (d,f), 2 cm (e).