Selective wireless control of a passive thermopneumatic micromixer24 Jan 2016 00:00
This paper reports a novel wireless control of a thermopneumatic zig-zag micromixer by selectively activating two passive wireless heaters enabled by an external radiofrequency magnetic field. Each heater generates heat when the external field frequency is tuned to the corresponding resonant frequency (fr) of the heater. The two heaters that are designed to have different f of 100 MHz and 130 MHz are selectively activated with a constant input power of 0.2 W by modulating the field frequency to their corresponding fr. Each heater is responsible for heating an air-heating chamber that is connected to a loading reservoir through a microdiffuser element, while the solutions pumped from each reservoir are mixed in a zig-zag micromixing element that ends with an outlet hole. The micromixer provides a mixing-ratio controllability with a flow rate of ~0.28 μL/min and biocompatibility, making it promising for biomedical applications, such as local drug delivery and cells culturing.
Micromixers play a core role in various biomedical applications, including drug delivery and lab-on-chip systems. However, the ability to implement micromixers in portable and implantable applications is still limited, due to the use of bulky magnetic cores or on-board power supplies. Such approaches pose several practical issues, such as device size and complexity, and feasibility for biomedical applications and multiple-actuators control. This study presents a passive wirelessly-controlled thermopneumatic micromixer to address the above mentioned issues. Additionally, the actuation mechanism eliminates the risk of mechanical failure caused by moving parts. The proposed actuation concept is realized through the use of radio-frequency magnetic field actuation method.