A microfluidic device for pulsatile transdermal delivery for neurobiological drugs

We present a novel microfluidic device for transdermal delivery of small quantities of drugs in brief time pulses for neurobiological studies. The device consists of dispensing and delivery channels connected to drug and buffer lines, respectively, and coupled by a check valve. The planar check valve and the microchannels are within a single flow layer which allows for simple fabrication and easy system integration. Drug and buffer lines are connected to separate pneumatic lines for briefly pulsatile driving to enable drug dispensing and delivery consecutively in a stage-shifting working principle. Experimental results demonstrate that our microfluidic device is capable of continuously delivering well-defined nanoliter-scale volumes of drug solution within time pulses tens of milliseconds in duration. Based on the investigation of the characteristics of the check valve, we have systematically characterized the drug delivery device in terms of the dispensed and delivered drug volumes under varying pneumatic driving pressures and pulse durations, showing that the device has virtually zero diffusive leakage and good controllability. Furthermore, in vitro pulsatile delivery into mouse brain tissue using this device has also been performed at controlled drug volumes, demonstrating the potentially wide application of this microfluidic device in various neurobiological studies.