Nano/micromotors are artificial robots at the nano/microscale that are capable of transforming energy into mechanical movement. In cancer diagnosis or therapy, such “tiny robots” show great promise for targeted drug delivery, cell removal/killing, and even related biomarker sensing. Yet biocompatibility is still the most critical challenge that restricts such techniques from transitioning from the laboratory to clinical applications. In this review, we emphasize the biocompatibility aspect of nano/micromotors to show the great efforts made by researchers to promote their clinical application, mainly including non-toxic fuel propulsion (inorganic catalysts, enzyme, etc.), bio-hybrid designs, ultrasound propulsion, light-triggered propulsion, magnetic propulsion, dual propulsion, and, in particular, the cooperative swarm-based strategy for increasing therapeutic effects. Future challenges in translating nano/micromotors into real applications and the potential directions for increasing biocompatibility are also described.

Humidity sensors deeply influence human manufacturing production and daily life, while researchers generally focus on developing humidity sensors with higher stability, higher linearity, rapid response time, etc. Yet, few people discuss measuring humidity in the microenvironment by miniaturizing sensor size into a microscale, in which the existing humidity sensors are difficult to reach. Accordingly, this study proposes a methodology for measuring relative humidity in the microscale by utilizing the distinctive morphologies of Equisetum spores across a range of relative humidities between 50% and 90%. Equisetum spores are responsive to changes in ambient relative humidity and remain in their original activities even after iron sputtering, which aims to endow the sensor with magnetic properties. The test performed in this study demonstrated a response time of 3.3 s and a recovery time of 3.6 s. In the first application, we employed such microscale sensors to work in the channel of the microfluidic chip or the cell migration microchip, as an example of working in the microenvironment. COMSOL Multiphysics 6.2 software was also used to simulate the change in relative humidity in such microchannels. Secondly, such microscale sensors are combined with smartphone-based microscopy to measure the humidity of the skin. These microscale sensors pave the new way to sensing humidity in microenvironments.