grasping. Magnetic actuation enables the wireless generation of forces and torques inside the body to actuate an untethered robot or to orient the tip of a catheter. Downloaded from https://www.science.org on November 16, 2021 Dupont et al., Sci. Robot. 6, eabi8017 (2021) 10 November 2021 SCIENCE ROBOTICS | REVIEW 4 of 15 animal procedures with Institutional Animal Care and Use Committee approval. Surgical automation Laparoscopic robot systems are used to perform a wide range of standard surgical tasks. They also inherently provide complete actuation of instrument motion as well as high-quality video and rich data sets describing instrument motion. As commercial offerings such as da Vinci have attained excellent levels of user-interface transparency, research focus has turned to use cases that might require supplementing teleoperated robotic surgery with automated assistance. Potential benefits of safe and effective automation of subtasks of a surgery include increased precision, fusion of nonvisual or haptic sensor information, adherence to precise preoperative plans, and amelioration of repetitive stress injury and other ergonomic hazards to surgeons. Barriers to safe and effective automation of selected surgical tasks are pronounced and include accurate three-dimensional (3D) reconstruction of the (changing) surgical field, repeatable and accurate control of elongated and flexible endoscopic mechanisms, accurate situational awareness by the agent of the overall operation’s state, robustness of task plans to sensor errors, unusual tissue properties, and emergency events. Work on this topic extends from developing 2D and 3D computer vision techniques to detect and localize robotic tools (9) to learning from observation of surgical subtasks (10). It also includes semiautomated in vivo (11) suturing, although the technologies in these studies required simplified visual environments. The development of autonomy remains a very active research frontier. Navigation, intraoperative imaging, and visualization Although surgical automation is often regarded as a novelty, some of the earliest medical robots, e.g., for milling cavities in the bone in joint replacement, offered a level of automation comparable with machine tools (5). Preoperative computed tomography or magnetic resonance images were used to generate operative plans that were carried out under computer control, while the clinician provided general supervision. As the field began to focus on soft tissue surgery, preprogrammed motions gave way to clinician-guided teleoperative control. Despite the change in control paradigm, the incorporation of image guidance, using either intraoperative or preoperative data, has become increasingly important for all types of robotic surgery, not just in laparoscopy. These techniques enable assessment of tissue perfusion and visualization of anatomical details below the tissue surface, minimizing the risks of damaging underlying vital structures such as nerves and blood vessels. For example, Intuitive Surgical has integrated near-infrared imaging with indocyanine green (ICG), allowing real-time assessment of microcirculation in vivo. ICG is a tricarbocyanine compound that is water soluble and can be injected intravenously. This “firefly” technology absorbs near-infrared light and, when injected, remains intravascular and can be used to assess blood perfusion, allowing, for example, the detection of decreased blood perfusion at an intestinal anastomosis that may result in anastomotic dehiscence (12). Contact force sensing and control Both manual and laparoscopic instruments remove the surgeon’s hand from tissues being manipulated and thus distort or completely Fig. 2. Medical robotics papers published in engineering and medical journal papers from 1990 to 2020. Curves report total numbers along with subsets corresponding to hot topics of laparoscopic robots, therapeutic rehabilitation robots, and assistive wearable robots. Note that 2020 publications were potentially reduced by coronavirus disease 2019 (COVID-19) shutdowns (data from Web of Science; see Materials and Methods). Downloaded from https://www.science.org on November 16, 2021 Dupont et al., Sci. Robot. 6, eabi8017 (2021) 10 November 2021 SCIENCE ROBOTICS | REVIEW 5 of 15 suppress force and tactile sensations. To preserve safe handling of tissues in tasks such as retraction, interaction forces must be sensed and controlled. Furthermore, tactile sensing would allow the recreation of tissue palpation at the manipulator during robotic surgery. Technical barriers to such sensing include the small (5 to 10 mm in diameter) size of laparoscopic instruments, heat and corrosiveness of sterilization measures in reusable instruments, and cost in singleuse instruments as well as the mechanics imposed between sensing point and the tool-tissue contact point or area. Progress to address this limitation has been made through the use of clever mechanical designs to separate pulling and grasping forces (13) and the introduction of new sensing technologies, such as capacitive compliant polymer load cells (14). Single-port laparoscopic robots As much as laparoscopic surgical approaches reduced invasiveness compared with standard open procedures, a typical manual or robotic procedure requires three or four incisions for individual