A bioinspired bubble removal method in microchannels based on angiosperm xylem embolism repair

Abstract

It is difficult to remove and eliminate bubbles in microchannels in many devices used in various biomedical fields, such as those needed for microfluidic immunoassays, point-of-care testing, and cell biology evaluations. Accumulated bubbles are associated with a number of negative outcomes, including a decrease in device sensitivity, inaccuracy of analysis results, and even functional failure. Xylem conduits of angiosperm have the ability to remove bubbles in obstructed conduits. Inspired by such an embolism repair mechanism, this paper proposes a bioinspired bubble removal method, which exhibits a prominent ability to dissolve bubbles continuously within a large range of flow rates (2 µL/min–850 µL/min) while retaining the stability and continuity of the flow without auxiliary equipment. Such a method also shows significant bubble removal stability in dealing with Newtonian liquids and non-Newtonian fluids, especially with high viscosity (6.76 Pa s) and low velocity (152 nL/min). Such advantages associated with the proposed bioinspired method reveal promising application prospects in macro/microfluidic fields ranging from 3D printing, implantable devices, virus detection, and biomedical fluid processing to microscale reactor operation and beyond.

Permeation-Enhanced Degassing Method Based on Xylem Embolism Repair and Gas Permeable Materials

“…The effects of structural parameters, flow rate, and liquid types on the performance of degassing were studied. The results show that the PED method shows better performance of degassing than the bioinspired bubble removal method previously published . To test the degassing performance of the PED method, a concentration gradient generator and a cell culture device were designed and fabricated.…”

“…Inspired by the embolism repair mechanism of angiosperms, our team has proposed a bioinspired bubble removal method, which exhibits the ability to dissolve bubbles continuously without auxiliary equipment. 26 But the bubble removal rate and bubble capture ability need to be further improved. Gas permeable materials, such as poly-(dimethylsiloxane) (PDMS) and silica gel, are widely used in the fabrication of lab-on-a-chip devices due to their advantages of good biocompatibility, optical transparency, and high gas solubility.…”

“…This paper proposes a permeation-enhanced degassing (PED) method inspired by the embolism repair mechanism of angiosperms and the high permeability of gas permeable materials. Redundant pits mimicking pits of xylem conduits have been proposed in our previous work 26 to keep bubbles from spreading between microchannels and maintain the continuity of the flow. A hydrophobic gas permeable material was used to improve the bubble capture capability of the device and accelerate the degassing process.…”

“…The results show that the PED method shows better performance of degassing than the bioinspired bubble removal method previously published. 26 To test the degassing performance of the PED method, a concentration gradient generator and a cell culture device were designed and fabricated. The results show that the PED method can dissolve bubbles rapidly and can run for a long time without auxiliary equipment while maintaining the stability and continuity of the flow.…”

“…Such a process is known as embolism repair, − in which process pits play an essential role in preventing air from spreading between adjacent conduits , and providing auxiliary hydraulic channels when conduits are blocked by bubbles. , After being captured, the air bubbles dissolve gradually until they are removed. Inspired by the embolism repair mechanism of angiosperms, our team has proposed a bioinspired bubble removal method, which exhibits the ability to dissolve bubbles continuously without auxiliary equipment . But the bubble removal rate and bubble capture ability need to be further improved.…”