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An ionic liquid (IL) electrospray thruster was developed for application in micro-nano satellites or gravitational wave detectors. The thruster employed a porous ceramic emitter with seven emitter strips located on its emission surface. Without any liquid-supply device, IL was delivered through porous media to emitter strips via capillary effect. Multiple emission sites then formed at the tip of each strip. A charged beam of up to 350 μA (with a current density of 540 μA cm −2 ) was stably produced in the negative mode. However, in the positive mode, a corona was observed which could prevent the thruster from emitting larger current. A time-of-flight mass spectrometer with significantly improved signal-to-noise ratio was built, which was used to obtain the mass distribution of the beam of the thruster. A retarding potential analysis was also performed. The test results showed that the thruster worked in the pure-ion regime, and delivered a maximum thrust of 67.1 μN with specific impulses of 3952 s and 3117 s in the positive and negative modes, respectively.

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A poly­(2-hydroxyethyl methacrylate) (pHEMA) hydrogel film was prepared by bulk polymerization. Then, it was surface modified by perfluorooctanoyl chloride to improve the anti-biofouling properties. Attenuated total reflectance-Fourier transform infrared (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDXS), and atomic force microscopy (AFM) analyses demonstrated that the uniform dense fluorinated layer had been successfully grafted onto pHEMA. The water contact angle (WCA) of the modified pHEMA film increased to 135°, while the surface energy decreased to 13.32 mN/m. The protein and bacterial adhesion properties of the modified pHEMA were decreased significantly. The in vitro cytotoxicity showed that the modified pHEMA was noncytotoxic. Thus, the fluorinated modification on the material surface was a convenient and effective method to establish a hydrophobic and anti-biofouling surface.

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