Microwave-actuated robot sensor for non-contact solution detection

The realization of specific target detection based on micro-robots has garnered broad interest. It generally requires separate systems for actuation and sensing, and this paper presents for the first time a robot sensor scheme based on non-contact microwave control and detection for solution sensing. The key components of the robot are a shape memory alloy (SMA) coil spring and a monopole antenna, supported by a structure fabricated through 3D printing. First, electromagnetic waves at 2.45 GHz generated by the microwave generator are emitted to the monopole antenna. The electromagnetic energy is then converted into Joule heating, which drive the robot sensor toward the sensing position. Next, the monopole antenna acts as the sensing tag, while the horn antenna as the receiver, detecting methanol and acetone solutions with the sensitivity of 0.208 dB/% and 0.187 dB/%, respectively. The detection is mediator-free and in-time, with a range of 5 %-25 % for both methanol and acetone. The robot sensor can traverse up to 10 cm. By increasing the microwave generator’s output power, the robot's range of motion can be extended, offering a potential idea for non-contact robot sensor drive and detection.