A novel air microfluidics-enabled soft robotic sleeve: Toward realizing innovative lymphedema treatment.

A proof of concept of a novel air microfluidics-enabled soft robotic sleeve to enable lymphedema treatment is presented. Compression sleeves represent the current, suboptimal standard of care, and stationary pumps assist with lymph drainage; however, effective systems that are truly wearable while performing daily activities are very scarce. This problematic trade-off between performance and wearability requires a new solution, which is addressed by an innovative microfluidic device. Its novelty lies in the use of light, small, and inexpensive air microfluidic chips (35 × 20 × 5 mm3 in size) that bring three major advantages compared to their traditional counterparts. First, each chip is designed with 16 fluidic channels with a cross-sectional area varying from 0.04 to 1 mm2, providing sequential inflation and uniform deflation capability to eight air bladders, thereby producing intentional gradient compression to the arm to facilitate lymph fluid circulation. The design is derived from the fundamentals of microfluidics, in particular, hydraulic resistance and paths of least resistance. Second, the air microfluidic chip enables miniaturization of at least eight bulky energy-consuming valves to two miniature solenoid valves for control increasing wearability. Third, the air microfluidic chip has no moving parts, which reduces the noise and energy needed. The cost, simplicity, and scale-up potential of developing methods for making the system are also detailed. The sequential inflation, uniform deflation, and pressure gradient are demonstrated, and the resulted compression and internal air bladder pressure were evaluated. This air microfluidics-enabled sleeve presents tremendous potential toward future improvements in self-care lymphedema management.

Semi-automated on-demand control of individual droplets with a sample application to a drug screening assay.

Automated control of individual droplets in microfluidic channels offers tremendous potential for applications requiring high accuracy and minimal user involvement. The feasibility of active droplet control has been previously demonstrated with pressure-driven flow control and visual feedback, but the manual operation required to perform droplet manipulations limited the accuracy, repeatability, and throughput. The present study improves upon the aforementioned challenges with a higher-level algorithm capturing the dynamics of droplet motion for a semi-automated control system. With a simple T junction geometry, droplets can now be automatically and precisely controlled on-demand. Specifically, there is ±10% accuracy for droplet generation, ±1.3% monodispersity for 500 µm long droplets and ±4% accuracy for splitting ratios. On-demand merging, mixing, and sorting are also demonstrated as well as the application of a drug screening assay related to neurodegenerative disorders. Overall, this system serves as a foundation for a fully automated system that does not require valves, embedded electrodes, or complex multi-layer fabrication.

Droplet Microfluidic System with On-Demand Trapping and Releasing of Droplet for Drug Screening Applications.

96-Well plate has been the traditional method used for screening drug compounds libraries for potential bioactivity. Although this method has been proven successful in testing dose-response analysis, the microliter consumption of expensive reagents and hours of reaction and analysis time call for innovative methods for improvements. This work demonstrates a droplet microfluidic platform that has the potential to significantly reduce the reagent consumption and shorten the reaction and analysis time by utilizing nanoliter-sized droplets as a replacement of wells. This platform is evaluated by applying it to screen drug compounds that inhibit the tau-peptide aggregation, a phenomena related to Alzheimer's disease. In this platform, sample reagents are first dispersed into nanolitre-sized droplets by an immiscible carrier oil and then these droplets are trapped on-demand in the downstream of the microfluidic device. The relative decrease in fluorescence through drug inhibition is characterized using an inverted epifluorescence microscope. Finally, the trapped droplets are released on-demand after each test by manipulating the applied pressures to the channel network which allows continuous processing. The testing results agree well with that obtained from 96-well plates with much lower sample consumption (∼200 times lower than 96-well plate) and reduced reaction time due to increased surface volume ratio (2.5 min vs 2 h).