Subsurface tactile tomography is now possible due to the smart bionic finger
The development of tactile perception in bio-robots has made it possible to obtain surface information about objects, such as their shape, texture, stiffness, and softness. However, acquiring subsurface information from materials remains a challenge. To address this limitation, researchers have introduced a smart bionic finger equipped with subsurface tactile tomography capability, which is capable of generating layer-by-layer images of the internal structure of materials. The bionic finger is equipped with an integrated tactile feedback system that responds quantitatively to force. A series of thresholds corresponding to the forces are set up to generate the slice images. The technology has been demonstrated by reconstructing a subsurface 3D profile of artificial human tissue and an encapsulated flexible circuit system.
Current subsurface information on materials is obtained through technologies like X-ray computed tomography (CT), ultrasonic tomography, magnetic resonance imaging (MRI), positron emission tomography (PET), profilometer, and optical CT. While these methods offer useful insights into material structures, they have limitations, such as exposure to ionizing radiation, low resolution, and long scanning times. The smart bionic finger offers an alternative non-optical way of non-destructively testing the human body and flexible electronics.
The smart bionic finger has carbon fiber beams (CFBs) as mechanoreceptors, which increase the probability of electron quantum tunneling between each two carbon fibers as the CFBs are compressed, leading to a decline in the transverse resistance of the CFBs. The bionic finger can respond to force quantitatively, and there is a linear relationship between the force and the threshold. When the bionic finger touches a material, the skin undergoes mechanical deformation such as compression, stretching, or drag. These deformations stimulate mechanoreceptors to emit electrical impulses that travel through the central nervous system (CNS) to the somatosensory cortex of the brain, where they are integrated to recognize the characteristics of the material.
In contrast to optical methods that require materials to be transparent, the smart bionic finger can recognize not only the surface but also subsurface characteristics of materials, even when the surface layer is softer than the inner layer. The bionic finger's subsurface tactile tomography has the potential to offer another strategy for acquiring subsurface or internal information about materials that is compatible with bio-robots.
The smart bionic finger could offer several potential benefits. It is non-invasive, non-destructive, and non-optical, making it a safer alternative to current methods of material imaging. It has the potential to provide higher resolution and faster imaging than current ultrasonic and MRI methods. The smart bionic finger's subsurface tactile tomography could be particularly useful for biomedical imaging, such as detecting tumors or bone fractures. Additionally, it could be used in the electronics industry to detect defects or inspect the internal structure of electronic components.