Zinc Oxide Nanowires on Printed Circuit Boards
Printed circuit boards (PCBs), which are widely used for the fabrication of electronic circuits, can only withstand rather low temperatures. For this reason, the fabrication of high-density, long ZnO nanostructures on PCBs still remains a complex task. In fact, in absence of a seed-layer, whose annealing would require high temperatures, solution-growth methods only allow to synthesize low-density arrays of nanowires. Here we evaluate methods for overcoming this issue and, as a prototype, demonstrate a simple displacement sensor.
Nanotransducers on printed circuit boards by rational design of high-density, long, thin and untapered ZnO nanowires
Abstract Nanotransducers can offer crucial advantages in comparison with conventional sensors and actuators. However, interfacing and packaging nanostructures into complete electronic systems is very complex. Here we describe a wet chemical method for cointegrating arrays of ZnO nanowires into systems on printed circuit boards (PCBs). First, we deposit on the PCB a MnOOH layer for reproducibly increasing the nanowires density. Afterwards, we numerically demonstrate that the ligand ethylenediamine, at the isoelectric point of the ZnO nanowires tips, can effectively control, at very low concentrations, both zinc speciation and supersaturation in the nutrient solution. Accordingly, we combine …
Piezoresistive Sensors from Bithiophene-fulleropyrrolidine Bisadducts Thin-Films
The phenomenon of piezoresistivity in materials is based on the separation of conductive domains triggered by mechanical strains, resulting in a variation of the electrical resistance.1 This property is at the core of sensors for wearable electronics, e-skins, human motion detectors and machine learning devices.2 Fundamental requirements include lightness, good transparency, high flexibility and sensitivity to tiny deformations. However, the fabrication of a system integrating all these features is challenging. Herein, we show a semitransparent piezoresistive sensor realized by an electropolymerized bithiophene‐fulleropyrrolidine bisadduct onto ITO/PET3 (see Figure 1a). The good outcome of …
Bending Sensors Based on Thin Films of Semitransparent Bithiophene-Fulleropyrrolidine Bisadducts
In this study, a novel bithiophene‐fulleropyrrolidine bisadducts system (bis‐Th2PC 60 ) was synthesized and electropolymerized by chronoamperometry onto flexible ITO/PET substrates. The resulting semitransparent thin film was characterized by XPS, FT‐IR, cyclic voltammetry and optical techniques, confirming the good outcome of the electropolymerization process. AFM investigations permitted to highlight an inherent disordered granular morphology, in which the grain‐to‐grain separation depends upon the application of bending. The electrical resistance of the thin film was characterized as function of bending (in the range 0°‐90°), showing promising responsivity to low bending angles (10°‐30°)…
Oil-in-Water fL Droplets by Interfacial Spontaneous Fragmentation and Their Electrical Characterization
Inkjet printing is here employed for the first time as a method to produce femtoliter-scale oil droplets dispersed in water. In particular, picoliter-scale fluorinated oil (FC40) droplets are printed in the presence of perfluoro-1-octanol surfactant at a velocity higher than 5 m/s. Femtoliter-scale oil droplets in water are spontaneously formed through a fragmentation process at the water/air interface using minute amounts of nonionic surfactant (down to 0.003% v/v of Tween 80). This fragmentation occurs by a Plateau-Rayleigh mechanism at a moderately high Weber number (10(1)). A microfluidic chip with integrated microelectrodes allows droplets characterization in terms of number and diamet…
High-density ZnO Nanowires as a Reversible Myogenic-Differentiation-Switch
Mesoangioblasts are outstanding candidates for stem-cell therapy and are already being explored in clinical trials. However, a crucial challenge in regenerative medicine is the limited availability of undifferentiated myogenic progenitor cells because growth is typically accompanied by differentiation. Here reversible myogenic-differentiation switching during proliferation is achieved by functionalizing the glass substrate with high-density ZnO nanowires (NWs). Specifically, mesoangioblasts grown on ZnO NWs present a spherical viable undifferentiated cell state without lamellopodia formation during the entire observation time (8 days). Consistently, the myosin heavy chain, typically express…
Low angle bending detection semi-transparent piezoresistive sensor
We designed, fabricated, and validated a piezoresistive bending sensor, a fundamental component of wearable electronic devices for monitoring human motion. The most diffused opaque carbon-based resistance flex sensors suffer from low detection for small bending angles. The sensor we here present is based on a semi-transparent active material (fulleropyrrolidine bisadducts polymer) and has the remarkable advantage of good electrical properties for low bending angles. The fabrication steps are effective since a pre-patterned ITO/PET surface is functionalized by chronoamperometric deposition, and the silver electrical contacts are inkjet printed. We propose a fitting function of the measured t…