Due to the high application value in intelligent robots, tactile sensors with large sensing area and multi-dimensional sensing ability have attracted the attention of researchers in recent years. Inspired by bionics of hairs on human skin, a flexible tactile sensor based on magnetic cilia array is developed, showing extremely high sensitivity and stability. The upper layers of the sensor are multiple magnetic cilia containing magnetic particles, while the lower layer is a serpentine flexible circuit board with a magnetic sensor array. When magnetic cilia are bent under force, the magnetic sensor array can detect changes in the magnetic field, thereby the magnitude and direction of external force can be obtained. The proposed sensor has a resolution of 0.2 mN with a working range of 0-19.5 mN and can distinguish the direction of external force. The large sensing area and short response time make this sensor suitable for sliding tactile detection, and experiments show that the sensor can be also applied in object recognition with a success accuracy of 97%. In addition to the shape of objects, the sensor can identify whether there is magnetism inside objects, making it of significant value in intelligent robots and modern medicine.
Inspired by the concept of bionics, a tactile and airflow motion sensor based on flexible double-layer magnetic cilia is developed, showing extremely high sensitivity in both force and airflow detection. The upper layer of the magnetic cilia is a flexible material mixed with magnetic particles, while the lower layer is a pure flexible material. This double-layer structure significantly improves magnetism while maintaining cilia flexibility. In addition, a metal tube pressing (MTP) method is proposed to overcome the difficulties in preparing large aspect ratio (over 30:1) cilia, offering simplicity and avoiding the use of large-scale MEMS instruments. The developed sensor has a detection range between 0 and 60 µN with a resolution of 2.1 µN for micro forces. It also shows great detection ability for airflow velocity with a sensitivity of 1.43 µT/(m/s). Experiments show that the sensor could be applied in surface roughness characterization and sleep apnea monitoring.
In the past two decades, biomimetic tactile sensing technology has been a hot spot in academia. It has prospective applications in many fields such as medical treatment, health monitoring, robot tactile feedback, and human-machine interaction. With the rapid development of magnetic sensors, biomimetic tactile sensing technology based on magnetic sensors (which are called magnetic tactile sensors below) has been widely studied in recent years. In order to clarify the development status and application characteristics of magnetic tactile sensors, this paper firstly reviews the magnetic tactile sensors from three aspects: the types of magnetic sensors, the sources of magnetic field, and the structures of sensitive bodies used in magnetic tactile sensors. Secondly, the development of magnetic tactile sensors in four applications of robot precision grasping, texture characterization, flow velocity measurement, and medical treatment is introduced in detail. Finally, this paper analyzes technical difficulties and proposes prospective research directions for magnetic tactile sensors.
Biomimetics , Technology , Humans , Magnetic Phenomena
