On‐Board Mechanical Control Systems for Untethered Microrobots

Abstract

An autonomous robot perceives its environment, makes decisions based on acquired information and programmed routines, and then actuates a movement or performs a manipulation task within that environment. The idea of microrobotics is primarily based on teleoperated mobile micromachines equipped with manipulation capabilities such as actuated grippers and drug‐loaded reservoirs. Due to miniaturization challenges, the majority of these micromachines are wirelessly actuated using magnetic fields or acoustic waves. A step toward complete autonomy is the development of on‐board control systems that directly transduce environmental stimuli such as heat and pressure into actuation, without going through the perception and computation cycles. Following the analogy of the central nervous system for the architecture of conventional autonomous robots, the next‐generation microrobots are expected to possess reflexes that would allow them to autonomously navigate inside structured microenvironments and perform targeted and triggered operations. Herein, the construction of on‐board control systems using stimuli–responsive materials, nonlinear mechanical mechanisms, and fluid–structure interactions is described. Recent advances in macroscale soft robotics and mechanical metamaterials are highlighted with the hope that they inspire solutions for microrobotics.

Bio-inspired physical intelligence for soft robotics

“…同时, 智能自愈材料在软体机器人中的使用将进一步提高机器人的鲁棒性 和使用寿命 [45] . 压力等环境刺激转换为驱动, 而无需经历感知和计算循环 [46] . Kobayashi 等人 [47] 提出了一种可生 物降解的热磁响应型软体微型抓手.…”

Small-scale soft grippers with environmentally responsive logic gates

“…The soft grippers with logicbased computation generally are at least centimeter-scale, tethered to sources of energy (e.g., electricity) and require several hard components, such as valves, motors, microcontrollers, electronic controls and onboard electronic chips. 9,[29][30][31][32] Recently, Preston and coworkers developed a soft logic-enabled gripper at the decimeterscale actuated by pneumatic valves and constant input air pressure. 33 However, the high level of sophistication of these components have greatly limited their applications to mainly small-scale soft robots due to several limitations and challenges.…”

“…1,[4][5][6][7][8] An intelligent small-scale soft robot (e.g., grippers) is expected to sense the information about the self and the environment, actuate and interact with the environment, and compute sensory inputs and outputs. 9 For example, some malignancies can cause both a localized increase in temperature and a decrease in pH in the microenvironment. Thus, for the purpose of targeting particularly the cancer cells, and decreasing the targeting of normal cells, it is desirable for the drug delivery and biopsy microrobots (e.g., small-scale soft grippers) to be responsive to both temperature and pH, which requires an AND gate.…”

Untethered Soft Microrobots with Adaptive Logic Gates

“…[1][2][3][4][5][6][7][8] Intelligent microrobots have reached a high-level of complexity, which is interacted with the surroundings and can acquire information about the self and the environment and then output the analyzed data as expected. [9,10] As a promising strategy, the research of microrobots has currently focused on developing microrobots with advanced stimulus-responsive abilities, which is a critical step toward micromachine intelligence. [11][12][13] Recently, many different kinds of soft microrobots based on responsive polymers have been developed with excellent performances such as programmable shape-morphing, [14,15] drug delivery, [16,17] sensors, [18,19] and motions (e.g., jumping, swimming and crawling), [20][21][22][23][24][25] which provide tremendous potential to achieve intelligent adaptation in diverse fields.…”

“…[13,26,27] However, combining adaptive logic-based computation with untethered soft microrobots is difficult because of the stiffness, flexibility, and size mismatch between rigid electrical components (e.g., electronic chips, control sensors, and batteries) and soft microrobots. [9,[28][29][30][31] Therefore, it is an enormous challenge to integrate adaptive computing functions into soft microrobots. Combining chemical logic gates with microrobots is a promising strategy to enable microrobots with binary logic computations.…”