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.

The piezoelectric valveless micropump with the characteristics of precise liquid delivery is widely utilized in the field of biomedicine. However, the improvement of the flow rate of the piezoelectric micropump relies on the increase in size and driving voltage, which hinders its application in the implantable medical field. This article proposes a double-layer chamber valveless piezoelectric micropump, which has the obvious advantages of small size and adjustable flow rate, and is expected to be applied to the treatment of implantable hydrocephalus. The overall size of the micropump is 10 mm × 10 mm × 4 mm, which can be implanted in the cerebral cortex. Combined with polydimethylsiloxane-polyethylene glycol terephthalate bonding technology, the double-layer chamber micropump solves the contradiction between miniaturization and large flow range. The flow rate generated by micropump under low voltage can be adjusted according to the amount of hydrocephalus. In order to reveal the mechanism of increasing the flow rate, the working efficiencies of the microvalve and micropump are studied in this article. The electric-solid-fluid coupling simulation and experimental tests obtained the optimal structural parameters: the divergence angle is 30°, the throat width is 300 μm, and the upper chamber depth is 100 μm. The proposed micropump can achieve the tunable flow rate of 2.16-51.74 μl min-1.

Microfluidic devices have developed a wide range of applications in the fields of biomedicine, chemistry, and analytical science. But it is easy to form and accumulate bubbles in microfluidic devices. These bubbles could decrease the detection sensitivity, cause inaccurate analysis results, and even damage the functional region of the device. Inspired by the embolism repair mechanism of angiosperms and the permeability of gas permeable materials, this work proposes a bioinspired permeation-enhanced degassing method. Bionic redundant pits are used in this method to keep bubbles from spreading between microchannels and maintain the continuity of the flow. A hydrophobic gas permeable material is used to enhance the bubble capture capability and accelerate the degassing process. This method can eliminate bubbles automatically and continuously in real time without auxiliary equipment. Compared to the bubble removal only depending on solution in water, the degassing effect of the permeation-enhanced degassing method shows about 1.6 times improvement in the same conditions, and the capability of trapping bubbles is improved by 1.33 times. In this paper, this method was integrated into a concentration gradient generator and a cell culture device. The results show that the concentration gradient generator with degassing structures can dissolve bubbles in a rapid way and reach the stability of the concentration gradient within 5–15 min. The degassing method can run for a long time and improve the cell density and cell viability of HeLa cells up to 2.64 and 1.12 times, respectively. The method has a broad application prospect in microfluidic fields including biomedical fluid processing, virus detection, and microscale reactor operation.