Cyborg insects: From free-state control to autonomous intelligent regulation

Cyborg insects are a convergence of biological organisms and artificial machinery, which is often referred to as insect-machine hybrid systems. These systems utilize an insect-machine interface (IMI) to gain control of the locomotion of insects and to facilitate the manipulation of their natural movement patterns. This control is achieved through external stimulus of the insect's peripheral or central nervous system and muscle fibers. Cyborg insects offer notable advantages over their counterparts-micro or bionic mobile robots-that merely mimic the physical attributes and movement patterns of insects. These benefits encompass: (1) The elimination of the need for complex designs associated with mechanical structure, drive, and control systems. This simplifies the developmental process substantially. (2) The integration of the superior sensorimotor performance of insects, which have been honed and refined through millions of years of evolution, providing them with an inherent, natural advantage. (3) The unique design where system power is supplied exclusively to control and communication modules, facilitating efficient command issuance and data transmission. (4) A compact size and natural insect-like appearance, making them virtually undetectable to both humans and other animals, thus offering exceptional stealth capabilities. (5) The mature feeding technology reduces the cost of insect culture, and makes the development cost of insect machine mixing system into controllable. Cyborg insects amalgamate the sensory cognition and movement capabilities inherent to insects with the high precision and controllability characteristic of micro-electromechanical systems (MEMS). This unique combination addresses and compensates for the limitations of micro robots, particularly concerning motion speed, distance, and payload. The attributes of straightforward system structure, exceptional motion perception, low energy consumption, and superior stealth make cyborg insects extremely valuable in both scientific research and practical engineering applications. Their stability across diverse motion modes makes them particularly suitable for complex real-world scenarios. For instance, they can be employed in search, rescue, and reconnaissance operations in disaster environments, especially those characterized by narrow, intricate terrains. Moreover, insect-machine hybrid systems offer a unique, versatile research platform with easily adjustable variables, providing promising opportunities for in-depth studies in neuroscience, entomology, and bionics. In this review, we first provide a comprehensive summary of the insect-machine hybrid system architecture, followed by a critical review of the significant strides made in the development of typical insect-machine hybrid systems based on different control principled. We aim to encapsulate the critical components that influence the locomotion control of these hybrid systems, including the characteristics of neuromechanism, neuromodulation methods, microstimulation systems, and control strategies. We also explore the significant research findings concerning several typical cyborg insects in detail. These findings are categorized based on virtual sensation, muscle execution, and central decision-making, all of which are grounded in the context of the neuromechanism. Additionally, to exploit cyborg insects effectively for practical applications, we delineate a research framework that addresses future cyborg insects, considering the current technical bottlenecks. We further discuss the technical challenges associated with cyborg insects, focusing on the sensorimotor neural mechanism of insects, neuromodulation methods, microcontrol systems and intelligent control strategies. In conclusion, we present an insightful forecast into the future research directions that hold promise in overcoming these challenges and unleashing the full potential of insect-machine hybrid systems. The journey towards these exciting prospects may prove transformative in our understanding of biology, technology, and the inspiring interface where they converge.