A review of centrifugal microfluidics in environmental monitoring
There is currently a gap in the use of centrifugal microfluidics in the field of environmental sensing. This review provides theoretical perspectives that have been demonstrated for applications in other domains and recommends adaptations for environmental sensing. Current approaches of centrifugal systems reported are primarily in the area of biosensing and electrochemical detection. In the case of current environmental monitoring devices discussed, a conversion process for developing centrifugal microfluidic platforms around currently reported transduction methods will be presented, covering design and manufacturing elements required for successful platforms. While the success of these reported systems is not in question, there is more to be done in advancing both automation, sample-to-detector interaction, simplification for the end user and portability, to facilitate long term deployable or in situ based environmental monitoring. Also included for discussion, are devices that have demonstrated the capability of sample processing and reagent mixing, as well as high-sensitivity sample characterisation with a number of varying detection techniques through transducer substitution. While in some cases, necessary sample preparation currently involves off-chip steps (such as cell lysis), others have incorporated these steps within the microfluidic platform, therefore through combinations of reported sample handling and detection strategies, more refined and flexible environmental monitoring tools can be achieved on a single platform using centrifugal microfluidics. Also considered will be the cost-effectiveness of the microfluidic platforms with current multi-use limitations. In the absence of suitable centrifugal microfluidic sensors, alternative chip-based systems, with significant relevance to environmental applications and which could be easily adapted to a centrifugal platform, are suggested. The primary technical challenge of this report is to demonstrate how these current centrifugal sensing systems could offer huge potential in the environmental sensing field, with minimal systematic modification, but a myriad of applications.