Micro/nanorobots for detecting and eliminating biological and chemical warfare agents

With the occurrence of terrorist incidents and the intensification of war situations, concerns about biological and chemical warfare agents (BCWAs) created by mankind are growing due to their chilling characteristics such as high toxicity, high fatality rate, mass destruction, imperceptibility to senses, rapid dissemination, and even easy availability. In most cases, even slight exposure to these BCWAs can be a disaster because of their lethal or incapacitating effects on humans. Hence, it is urgently demanding to develop effective methodologies for sensitive detection and efficient neutralization of BCWAs in a specific scenario. Among various techniques, micro/nanorobots (MNRs), which can transfer energy from surroundings into kinetic energy for self-propelled or field-powered movement, have emerged as state-of-the-art tools to actively combat biological and chemical threats. In this review, the latest research progress in MNRs for sensing and detoxification of BCWAs is presented. Toxins and pathogenic bacteria have been selected as the representatives for biological warfare agents, whereas nerve agents were chosen as typical chemical warfare agents. Besides, the working principles of MNRs based on their locomotion features (e.g., velocity changes) and constructed material characteristics (e.g., fluorescent on/off switch, photocatalytic effect, adsorption, and antibody-antigen recognition) in terms of sensing and detoxification are summarized. Finally, current challenges and future perspectives for the development of fuel-powered and field-driven MNRs and their application in sensing and removing BCWAs are discussed.