Bubble-propelled micro/nanomotors: a robust platform for the detection of environmental pollutants and biosensing

Abstract

The sensitive and rapid detection of a variety of hazardous environmental pollutants and bio-analytes such as microorganisms and biomolecules is of great importance for environmental and health care monitoring. Thus, significant progress has been made in the development of numerous sensor platforms for the quick and reliable sensitive detection of these analytes. However, most of the sensor platforms require complex technology, skillful personnel, prolonged operation, and laborious protocols, which limit their use worldwide, especially in low- and middle-income countries. Over the past few decades, the emergence and progress of nanotechnology have revolutionized the field of sensing. Particularly, the birth of self-propelled micro/nanomotors has become an area of interest in the current era owing to their versatility, ranging from environmental monitoring to biosensing. These are synthetic tiny multifunctional intelligent systems, capable of converting external energy such as light, magnetic field, ultrasound, electric field, and chemical fuel to kinetic energy and accomplishing tedious jobs. Among the external driving sources, chemically driven micromotors based on the bubble propulsion mechanism hold considerable promise in sensing on account of their greater propulsion rate, enhanced fluid mixing, and mass transfer. Employing this advantage, many leading research groups have focused on the fabrication of differently shaped bubble-propelled micromotors for the sensitive and selective detection of targets by functionalizing the motors with specific recognition units. In this review, we highlight the current progress in bubble-propelled micro/nanomotors for the detection of various environmental pollutants and bioanalytes such as microorganisms, cells, and biomolecules, and discuss their sensing mechanism. Finally, the challenges and limitations of these micromotors are presented together with their future direction.