Improving the interface between copper and carbon nanotubes (CNTs) offers a straightforward strategy for the effective manufacturing and utilisation of Cu-CNT composite material that could be used in various industries including microelectronics, aerospace and transportation. Motivated by a combination of structural and electrical measurements on Cu-M-CNT bimetal systems (M = Ni, Cr) we show, using first principles calculations, that the conductance of this composite can exceed that of a pure Cu-CNT system and that the current density can even reach 10 A cm. The results show that the proper choice of alloying element (M) and type of contact facilitate the fabrication of ultra-conductive Cu-M-CNT systems by creating a favourable interface geometry, increasing the interface electronic density of states and reducing the contact resistance. In particular, a small concentration of Ni between the Cu matrix and the CNT using either an "end contact" and or a "dot contact" can significantly improve the electrical performance of the composite. Furthermore the predicted conductance of Ni-doped Cu-CNT "carpets" exceeds that of an undoped system by ∼200%. Cr is shown to improve CNT integration and composite conductance over a wide temperature range while Al, at low voltages, can enhance the conductance beyond that of Cr.
the relatively simple mechanism involved in converting mechanical energy into electrical signals, [15,16] wide material selection, [17,18] and light weight. [19] Triboelectric generators produce active electric output due to mechanical motion-driven contact electrification and charge induction. These generators can also be used as sensors, where the output signal can be monitored for sensing movement. [20][21][22][23][24] One particular type of triboelectric sensor designed for motion sensing, based on grated electrode structures on triboelectric surfaces, has been found to be potentially reliable, of high resolution, and direction sensitive with a wide selection of feasible materials. [25,26] Typically, these sensors comprise multiple alternating strips of two different triboelectric materials for contact electrification, and grated comb-like electrodes or interdigitated electrodes for charge induction. A commonly reported device structure involves a "mover" that slides over a "stator," with the contacting surface made up of triboelectric material strips, and the grated electrodes positioned on the backside of both the mover and the stator to form a sliding mode triboelectric sensor. [21] The relative sliding motion between the two different materials gives rise to a triboelectric charge that is picked up by the electrodes. If the electrodes are positioned only on the backside of the stator, then this structure gives rise to a freestanding mode triboelectric sensor (no electrical contact is needed from the mover). [27] To achieve high resolution, the metallic electrode gratings must be narrow (submillimeter), usually achieved via photolithography, [28] physical deposition, [26,29] or ion-etching [30] methods. These methods are not particularly cost effective and are generally inefficient for fast prototyping. At the same time, polymers that have good triboelectric properties are difficult to fabricate into the desired fine structures or finely patterned strips by the conventional lithography or physical deposition methods. This has led to the vast majority of the current grated-structure triboelectric sensors being built with metal strips as the active triboelectric material, [18,31] even though these are not particularly well-suited for triboelectric applications. Reports on all polymer-grated triboelectric sensors are thus tellingly rare, even though such devices could potentially offer better resolution and higher signal-to-noise ratios in motion sensing applications.Triboelectric motion sensors, based on the generation of a voltage across two dissimilar materials sliding across each other as a result of the triboelectric effect, have generated interest due to the relative simplicity of the typical grated device structures and materials required. However, these sensors are often limited by poor spatial and/or temporal resolution of motion due to limitations in achieving the required device feature sizes through conventional lithography or printing techniques. Furthermore, the reliance on metallic components t...
Summary Force sensors that are thin, low-cost, flexible, and compatible with commercial microelectronic chips are of great interest for use in biomedical sensing, precision surgery, and robotics. By leveraging a combination of microfluidics and capacitive sensing, we develop a thin, flexible force sensor that is conformable and robust. The sensor consists of a partially filled microfluidic channel made from a deformable material, with the channel overlaying a series of interdigitated electrodes coated with a thin, insulating polymer layer. When a force is applied to the microfluidic channel reservoir, the fluid is displaced along the channel over the electrodes, thus inducing a capacitance change proportional to the applied force. The microfluidic molds themselves are made of low-cost sacrificial materials deposited via aerosol-jet printing, which is also used to print the electrode layer. We envisage a large range of industrial and biomedical applications for this force sensor.
Highlights Aerosol-jet printing is used to fabricate microfluidic devices with customised geometries, including steps and slopes. A rapid prototyping method for producing bespoke molds for microfluidic devices with precise channel functionalization. The functionalization capability is demonstrated by rendering a section of a microfluidic channel hydrophilic using PVA.
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