Magnetic nanofluid-based liquid marble for a self-powered mechanosensation

Magnetic nanofluid possesses the characteristic of interfering with the propagation of the magnetic field, endowing it with the sensing property in motion. However, the residual adhesion of magnetic nanofluid as it flows over solid surfaces remains an open question. Liquid marbles allow for quantities of liquids to be encapsulated by hydrophobic particles, ensuring a unique nonstick property for utilization in different applications. In this study, being capsuled by hydrophobic nano-/microscale powders, a magnetic nanofluid-based liquid marble (MNLM) with well mechanical stability has been fabricated. A magnetic nanofluid posture detector (MNPD), which consists of an MNLM, a magnetic tube, and coils, has been assembled that can convert mechanical energy to electricity as it freely rolls on the solid surface. Gesture recognition can be achieved when combining five MNPDs with fingers. The fabricated MNPD possesses a good signal recognition capability, which can separately distinguish the bending of each finger. Moreover, a variety of language hand gestures with specific meanings (digits, letters, “OK,” and “I Love You”) can be further recognized through corresponding combinations. The potential of MNPD in the realm of gesture recognition will offer a novel avenue for flexible wearables.