Polymeric nanofibers are finding increasing number of applications and hold the potential to revolutionize diverse fields such as tissue engineering, smart textiles, sensors, and actuators. Aligning and producing high aspect ratio fiber arrays (length/diameter > 2 000) in the sub‐micron and nanoscale diameters has been challenging due to fragility of polymeric materials, thus making it difficult to deposit them as one dimensional structures functionally interfaced with other systems. Here, we present a pseudo dry spinning technique which allows precise control on fiber diameters and further allows deposition of fiber arrays in aligned configurations. Control on fiber diameters ranging from 50–500 nm and having lengths of several millimeters is achieved by altering the polymeric solution concentration. In the dilute and semi‐dilute unentangled concentration domain droplets or beaded fibers are observed to form. Smooth uniform diameter fibers are observed to form at the onset of semi‐dilute entangled concentration regime. For a given molecular weight, the increase in fiber diameter with increasing solution concentration is attributed to both the increase in the entanglement density and the decrease in the radius of gyration of solvated polymer molecules. Using this technique polymeric fiber arrays in single and multiple layers are demonstrated which can be used towards developing strong textiles, biological scaffolds, and sensor networks.
The 256×1 linear array of multiple quantum wells infrared photodetector (QWIP) is designed and fabricated for the peak response
wavelength at λP = 14.6 μm. The response spectral width is bigger than 2.2 μm. The two-dimensional (2D) diffractive coupling grating has been
formed on the top QWIP photosensitive pixel for coupling the infrared radiation to the infrared detective layers. The performance
of the device at VB = 3 V and T = 45 K has the responsibility 4.28×10−2 (A/W), the blackbody detectivity Db* = 5.14×109 (cm·Hz1/2/W), and the peak detectivity Dλ* = 4.24× 1010 (cm·Hz1/2/W). The sensor pixels are connected with CMOS read out circuit (ROC) hybridization by indium bumps. When integral time is
100 μs, the linear array has the effective pixel of QWIP FPA Nef of 99.2%, the average responsibility (V/W) of 3.48×106 (V/W), the average peak detectivity Dλ* of 8.29×109 (cm·Hz1/2/W), and the non-uniformity UR of 5.83%. This device is ready for the thermal image application.
Supported by the National Natural Science Foundation of China (Grant No. 10374095) 相似文献
A method is presented for predicting the performance of multilayered piezoelectric structures which demonstrate two, loosely coupled compressional modes of vibration. A linear systems, lattice approach is developed using a matrix formulation for implementation of the transducer transfer functions in the frequency domain. The technique is computationally efficient, providing good results over a key range of transducer dimensions and is especially useful for the practical evaluation of multilayered, linear or diced array structures. 相似文献
The radius of curvature of the input surface of a thick lens spatial integrator array is a free parameter that can be customized for a maximum flux transfer efficiency. With this procedure each element is different but the spatial integration feature remains for the whole array. The calculation is based on a real ray-tracing evaluation that also takes into account the transmissivity of the diopters. The flux transfer on the synthetic image is doubled when the input surfaces are propoerly optimized. 相似文献
Fullerene nanowire arrays with well‐defined size and length have been prepared by a controllable technique. Fullerene molecules such as C60 are introduced into the pores of anodic aluminum oxide (AAO) templates under a direct current (DC) electric field and polymerized in the pores. Structure analysis shows that the C60 nanowires are mainly polycrystalline, and a rhombohedral polymeric phase is observed in their vibration spectra. The electrical conductivity of so‐prepared nanowire arrays show a semiconducting behavior. The ability to fabricate the fullerene nanowire arrays with controlled structures represents an important step toward the development of chemical sensors and nanoscale electronic devices based on fullerenes. 相似文献