Exosomes are essential early biomarkers for health monitoring and cancer diagnosis. A prerequisite for further investigation of exosomes is the isolation, which is technically challenging due to the complexity of body fluids. This paper presents the development of an integrated microfluidic chip for exosomes isolation, which combines the traditional immunomagnetic bead-based protocol and the recently emerging microfluidic approach, resulting in benefits from both the high-purity of the former and the automated continuous superiority of the latter. The chip was designed based on an S-shaped micromixer with embedded baffle. The excellent mixing efficiency of this micromixer compared with Y-shaped and S-shaped micromixers was verified by simulation and experiments. The photolithography technique was employed to fabricate the integrated microfluidic chip, and the manufacturing process was elucidated. We finally established an experimental platform for exosomes isolation with the fabricated microfluidic chip built in. Exosomes isolation experiments were conducted using this platform. The distribution and morphology of the isolated exosomes were observed by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Quantitative size analyses based on transmission electron micrographs indicated that most of the obtained particles were between 30 and 150 nm. Western blot analyses of the isolated exosomes and the serum were conducted to verify the platform’s capability of isolating a certain subpopulation of exosomes corresponding to specified protein markers (CD63). The complete time for isolation of 150 μL serum samples was approximately 50 min, which was highly competitive with the reported existing protocols. Experimental results proved the capacity of the established integrated microfluidic chip for exosomes isolation with high purity, high integrity, and excellent efficiency. The platform can be further developed to make it possible for practical use in clinical applications as a universal exosomes isolation and characterization tool.

The existing nano-positioning stages are driven by the piezoelectric ceramics, which have features of high accuracy and resolution, but the traditional positioning stage could not meet the requirement of large working space because the displacement of the piezoelectric ceramics is only tens of microns. To solve the contradiction between high accuracy and large working space, a novel non-resonant piezoelectric linear actuator, which adopted the two parallel v-shaped stators as the double driving feet, was proposed, and both its working principle and structure were discussed in detail. The actuator was used to drive the positioning stage directly to obtain the performance of nano-positioning and large working stroke. The experiment results show that the resolution of the actuator is 0.015 mm, and its stable maximum motion speed is 17.4 mm/s, while the degree-offreedom of step resolution of teach nano-positioning stage is 0.018 mm, 0.016 mm, and 0.3 mrad, respectively. Compared with the traditional positioning stage, the nano-positioning stage driven by the actuators directly also has excellent working stroke. The key performance of both high resolution and large working stroke of the nano-positioning stage was realized based on different motion modes of only one piezoelectric actuator.

No abstract

No abstract

No abstract