The recent development and commercialization of microelectromechanical systems (MEMS)/nanoelectromechanical systems (NEMS) has brought the related challenge of independently powering such systems. ...The concept of the nanogenerator (NG) has shown potential for harvesting energy from the ambient environment to power MEMS/NEMS. Kinetic energy harvesting NGs based on the piezoelectric properties of ZnO nanowires have attracted much interest. In this paper, we have fabricated hydrothermally synthesized ZnO-based NGs following the procedures standardized in the published literature. Likewise, reference NGs without ZnO piezoelectric material were fabricated in parallel with the ZnO NGs. The voltage output of both the ZnO NG and the reference NG was measured given a 10-Hz cyclic vertical load. Unexpectedly, both the ZnO and the reference NG were found to produce 3 mV with 0.451 N of load. A finite-element model was created to determine that the voltage potential of the NG should be about 1 mV with the given load. A possible explanation for this unexpected behavior is that the measured signals are not entirely piezoelectric in nature. Rather, the signals recorded from the NGs may be some alternate phenomenon, such as the triboelectric, flexoelectric, or electret effect.
The production of high-quality semiconducting nanostructures with optimized electrical, optical, and electromechanical properties is important for the advancement of next-generation technologies. In ...this context, we herein report on highly obliquely aligned single-crystalline zinc oxide nanosheets (ZnO NSs) grown via the vapor–liquid–solid approach using r-plane (01–12) sapphire as the template surface. The high structural and optical quality of as-grown ZnO NSs has been confirmed using high-resolution transmission electron microscopy and temperature-dependent photoluminescence, respectively. To assess the potential of our NSs as effective building materials in high-performance flexible electronics, we fabricate organic (parylene C)/inorganic (ZnO NS) hybrid field-effect transistor (FET) devices on flexible substrates using room-temperature assembly processes. Extraction of key FET performance parameters suggests that as-grown ZnO NSs can successfully function as excellent n-type semiconducting modules. Such devices are found to consistently show very high on-state currents (I on) > 40 μA, high field-effect mobility (μeff) > 200 cm2/(V s), exceptionally high on/off current modulation ratio (I on/off) of around 109, steep subthreshold swing (s-s) < 200 mV/decade, very low hysteresis, and negligible threshold voltage shifts with prolonged electrical stressing (up to 340 min). The present study delivers a concept of integrating high-quality ZnO NS as active semiconducting elements in flexible electronic circuits.
From the multitude of nanostructures under active research, Zinc Oxide (ZnO) nanowires (NWs) have attracted enormous attention due to the materials’ unique electrical, optical, mechanical and ...piezoelectric properties. Since 10 years, piezoelectric nanocomposites based nanogenerators (NGs) have gained extensive attention for their applications in mechanical energy harvesters and self-powered tactile sensors. Other emerging applications of ZnO single-crystalline NWs are high performance field-effect transistors (FETs) targeting low power applications, or highly sensitive FET based biosensors. A possible route to reduce the price of these devices is using low cost manufacturing over large-area substrates, and hydrothermal synthesis appears as a promising solution.
First we will present here a facile, cost-effective and industrially scalable process flow for the fabrication of high performance stretchable nanogenerators (SNG) on polydimethylsiloxane (PDMS) substrate. The SNG device exhibits excellent performance with a 35 µW peak output power achieved from a 8 cm2 device under a pressure of 100 kPa. Moreover, we investigated ZnO nanostructures for FETs on both conventional rigid (Si/SiO2) and unconventional flexible substrates (polyethylene terephthalate PET). The electrical characterization results (field-effect mobility, on/off current ratio, sub-threshold swing) reveal the potential of the present nanomaterials for high performance electronics. The key issues of efficient NGs and FETs will be presented, taking into account the technological constraints. This opens horizons for integrating high quality ZnO nanostructures as active semiconducting elements for autonomous flexible electronic circuits.
Dual-Gate Transistors Using Contact Printed ZnO Nanowires Neto, Joao; Dahiya, Abhishek S.; Christou, Adamos ...
2023 IEEE International Conference on Flexible and Printable Sensors and Systems (FLEPS),
2023-July-9
Conference Proceeding
Large-area printed electronics has garnered considerable attention owing to advantages such as low-cost and resource efficiency. Thin films of various organic, inorganic and/or metal oxide materials ...have been reported in literature along with single gate transistors based on them. Advancing this further, we report here printed dual-gate transistors, which can open new opportunities for implementation of energy efficient neuromorphic electronics. The dual-gate transistor presented here is based on contact printed ZnO nanowires as a channel material. The electrical characterizations, for both top- and bottom-gated transistors confirms excellent channel control, giving peak field-effect mobility of 12 cm 2 /Vs (top-gate) and 5 cm 2 /Vs (bottom-gate) and high on/off current modulation ratio (I on/off ) of >10 5 for both gates. The dual-gate transistors have the capability to tune/adjust their threshold voltage, which can be used for learning process and hence to build with minimal resources the next generation of neuromorphic-based computing hardware.
Out‐of‐plane or 3D electronics on flexible substrates are an interesting direction that can enable novel solutions such as efficient bioelectricity generation and artificial retina. However, the ...development of devices with such architectures is limited by the lack of suitable fabrication techniques. Additive manufacturing (AM) can but often fail to provide high‐resolution, sub‐micrometer 3D architectures. Herein, the optimization of a drop‐on‐demand (DoD), high‐resolution electrohydrodynamic (EHD)‐based jet printing method for generating 3D gold (Au) micropillars is reported. Libraries of Au micropillar electrode arrays (MEAs) reaching a maximum height of 196 µm and a maximum aspect ratio of 52 are printed. Further, by combining AM with the hydrothermal growth method, a seedless synthesis of zinc oxide (ZnO) nanowires (NWs) on the printed Au MEAs is demonstrated. The developed hybrid approach leads to hierarchical light‐sensitive NW‐connected networks exhibiting favorable ultraviolet (UV) sensing as demonstrated via fabricating flexible photodetectors (PDs). The 3D PDs exhibit an excellent omnidirectional light‐absorption ability and thus, maintain high photocurrents over wide light incidence angles (±90°). Lastly, the PDs are tested under both concave and convex bending at 40 mm, showing excellent mechanical flexibility.
Out‐of‐plane electronics on flexible substrates are demonstrated by adopting a hybrid approach involving additive manufacturing for achieving high‐aspect‐ratio printed gold micropillars and a hydrothermal growth method for obtaining zinc oxide nanowires on gold micropillar electrode arrays. This leads to hierarchical light‐sensitive nanowire‐connected networks, exhibiting favorable ultraviolet sensing and excellent omnidirectional light‐absorption ability.
The Printed Electronics (PE) is expected to revolutionise the way electronics will be manufactured in the future. Building on the achievements of the traditional printing industry, and the recent ...advances in flexible electronics and digital technologies, PE may even substitute the conventional silicon-based electronics if the performance of printed devices and circuits can be at par with silicon-based devices. In this regard, the inorganic semiconducting materials-based approaches have opened new avenues as printed nano (e.g. nanowires (NWs), nanoribbons (NRs) etc.), micro (e.g. microwires (MWs)) and chip (e.g. ultra-thin chips (UTCs)) scale structures from these materials have been shown to have performances at par with silicon-based electronics. This paper reviews the developments related to inorganic semiconducting materials based high-performance large area PE, particularly using the two routes i.e. Contact Printing (CP) and Transfer Printing (TP). The detailed survey of these technologies for large area PE onto various unconventional substrates (e.g. plastic, paper etc.) is presented along with some examples of electronic devices and circuit developed with printed NWs, NRs and UTCs. Finally, we discuss the opportunities offered by PE, and the technical challenges and viable solutions for the integration of inorganic functional materials into large areas, 3D layouts for high throughput, and industrial-scale manufacturing using printing technologies.
Electronic systems possessing skin‐like morphology and functionalities (electronic skins e‐skins) have attracted considerable attention in recent years to provide sensory or haptic feedback in ...growing areas such as robotics, prosthetics, and interactive systems. However, the main focus thus far has been on the distributed pressure or force sensors. Herein a thermoreceptive e‐skin with biological systems like functionality is presented. The soft, distributed, and highly sensitive miniaturized (≈700 µm2) artificial thermoreceptors (ATRs) in the e‐skin are developed using an innovative fabrication route that involves dielectrophoretic assembly of oriented vanadium pentoxide nanowires at defined locations and high‐resolution electrohydrodynamic printing. Inspired from the skin morphology, the ATRs are embedded in a thermally insulating soft nanosilica/epoxy polymeric layer and yet they exhibit excellent thermal sensitivity (−1.1 ± 0.3% °C−1), fast response (≈1s), exceptional stability (negligible hysteresis for >5 h operation), and mechanical durability (up to 10 000 bending and twisting loading cycles). Finally, the developed e‐skin is integrated on the fingertip of a robotic hand and a biological system like reflex is demonstrated in response to temperature stimuli via localized learning at the hardware level.
This work presents anelectronic skin (e‐skin) having distributed, miniaturized temperature sensors or thermoreceptors and a peripheral nervoussystem‐like localized learning scheme, allowing robots to mimic the thermal pain like reflexes. The vanadium pentoxide nanowires (NWs)‐based thermoreceptors are developed with dielectrophoresis approach for precise assembly and high‐resolution printing of NWs. The e‐skin exhibits excellent thermal sensitivity, fast response, and flexibility.
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