Improving the performance of IPMCs with a gradient in thickness

Natural Science Foundation of Fujian Province of China [2011J05140]; Fundamental Research Funds for Central Universities of Xiamen University [2011121045]An ionic polymer metal composite (IPMC) is a kind of electro-active polymer. Due to the properties of low driving voltage, large deformation, flexibility and lightness, it is becoming one of the more popular from a diversity of smart materials. In this study, a novel structure of Nafion (R) film is proposed to improve the performance of an IPMC. IPMC samples with a gradient structure in thickness are fabricated and their performance is investigated to confirm the validity of the gradient structure. The deformation displacement and the blocking force are compared under AC and DC voltage by experiments. The results indicate that the structure of gradient in thickness would improve the performance both in deformation displacement and blocking force

High-Performance Detection of Exosomes Based on Synergistic Amplification of Amino-Functionalized Fe₃O₄ Nanoparticles and Two-Dimensional MXene Nanosheets

Exosomes derived from cancer cells have been recognized as a promising biomarker for minimally invasive liquid biopsy. Herein, a novel sandwich-type biosensor was fabricated for highly sensitive detection of exosomes. Amino-functionalized Fe3O4 nanoparticles were synthesized as a sensing interface with a large surface area and rapid enrichment capacity, while two-dimensional MXene nanosheets were used as signal amplifiers with excellent electrical properties. Specifically, CD63 aptamer attached Fe3O4 nanoprobes capture the target exosomes. MXene nanosheets modified with epithelial cell adhesion molecule (EpCAM) aptamer were tethered on the electrode surface to enhance the quantification of exosomes captured with the detection of remaining protein sites. With such a design, the proposed biosensor showed a wide linear range from 102 particles μL−1 to 107 particles μL−1 for sensing 4T1 exosomes, with a low detection limit of 43 particles μL−1. In addition, this sensing platform can determine four different tumor cell types (4T1, Hela, HepG2, and A549) using surface proteins corresponding to aptamers 1 and 2 (CD63 and EpCAM) and showcases good specificity in serum samples. These preliminary results demonstrate the feasibility of establishing a sensitive, accurate, and inexpensive electrochemical sensor for detecting exosome concentrations and species. Moreover, they provide a significant reference for exosome applications in clinical settings, such as liquid biopsy and early cancer diagnosis

Electrohydrodynamic direct-writing of three-dimensional multi-loop nanofibrous coils

National Natural Science Foundation of China [51305373, 51305371]; Natural Science Foundation of Fujian Province of China [2013J05083]This paper studies the whipping deposition behavior of straight charged jets of Near-Field Electrospinning. A micro 3D structure of multi-loop nanofibrous coil was printed on a silicon collector. The whipping motion resulted from Coulomb force caused the charged jet to deposit and form a coiled structure. With the guidance of deposited nanofiber, the charged jet deposited layer by layer to build up a 3D nanofibrous coiled structure with 3-50 loops. The diameter of the coiled structure ranged from 4 to 60 mu m. The number of loops decreased with the increase of collector motion speed, due to shorter post-deposition relaxing time. With higher stress inside the charged jet, PEO solution of higher concentration led to fewer loops but larger diameter of the coil. This work provides a promising method to study the control technology of charged jet printing, which may push forward the development of micro 3D inkjet printing technology

Multi spinnerets electrospinning with assistant sheath gas

Conference Name:9th IEEE International Conference on Nano/Micro Engineered and Molecular Systems, IEEE-NEMS 2014. Conference Address: Waikiki Beach, HI, United states. Time:April 13, 2014 - April 16, 2014.Chinese International NEMS Society (CINS); City University of Hong Kong; et al.; IEEE Nanotechnology Council; University of California, Los Angeles; University of Hawai'iA multi nozzle electrospinning spinneret with assistant sheath gas was designed to realize the multi jets injection, by which the production rate of nanofiber can be promoted. The sheath gas around the nozzle decreased the surface charge density, and provided an excess stretching force to increase the motion speed of charged jet. The diameter of charged jet was also decreased by the sheath gas further. On the other hand, the sheath gas also reduced the mutual disturbance among charged jets, by which stable multi jets injection can be gained. The stretching force increased along with air pressure of sheath gas. Then, both of the nanofiber diameter and the critical voltage required for jet injection decreased with the increase of air pressure. With the increase of sheath gas pressure, the uniformity of electrospinning nanofiber can be also improved. As sheath gas pressure increased from 0kPa to 50kPa, the critical voltage required for the jet injection from multi nozzle decreased from 5kV to 0.3kV, meanwhile the averaged diameter of electrospinning nanofiber decreased from 472.80nm to 230.60nm. Multi nozzles electrospinning spinneret with sheath gas provided an excellent way to increase the production speed of nanofiber, and promoted the application of electrospinning technology. ? 2014 IEEE

Electrosprayed membrane with heat treatment

Conference Name:9th IEEE International Conference on Nano/Micro Engineered and Molecular Systems, IEEE-NEMS 2014. Conference Address: Waikiki Beach, HI, United states. Time:April 13, 2014 - April 16, 2014.Chinese International NEMS Society (CINS); City University of Hong Kong; et al.; IEEE Nanotechnology Council; University of California, Los Angeles; University of Hawai'iIn this paper, electrospray technology was utilized to fabricate micro membrane. The stable cone-jet injection mode was the key role to atomize uniformity particle and smooth membrane. As applied voltage ranged from 2.5kV to 7.5kV, the stable cone-jet model was built up. When the applied voltage increased from 2.5kV to 7.5kV, the average linear jet length increased from 3.699mm to 4.653mm under the stable cone-jet mode. Under the smaller distance between the nozzle and collector of 3～5cm, electrospray particles with higher solvent content was syncretized into membrane. Larger applied voltage led to higher surface charge density and multiple jets injection mode, in which electrospray particles can be syncretized into membrane structure. The uniformity and compactness of the membranes can be improved through the heat treatment. Smooth and uniform membrane can be fabricated with the heat treatment temperature of 100°C. With the help of heat treatment, the thickness of electrospray membrane was decreased from 9.06 μm to 6.41 μm. Electrospray technology provides an excellent way to fabricate polymer micro membrane and had great application potential. ? 2014 IEEE