Introduction of the revolutionary drop-on-demand (DoD) inkjet printing technique for microelectronics allows the use of flexible substrate, organic and inorganic materials, and low-cost volume fabrication. However, inks of different functional materials for varieties of applications are still under development. Polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE), a potential candidate for mechanical and acoustic sensors, actuators, energy harvesting and nonvolatile memory applications, is a copolymer that exhibits piezo-, pyro-and ferro-electric properties. During this work, inkjetprinted films using high molecular weight PVDF-TrFE were developed and characterized to investigate their morphology and crystallinity. Modified waveform and very low jetting frequency have been used to accommodate relaxation time of the polymeric ink during jetting. Crystallographic studies confirm the presence of a β-phase, which exhibits spontaneous polarization per unit cell.

No abstract

A capacitive acoustic resonator developed by combining three-dimensional (3D) printing and two-dimensional (2D) printed electronics technique is described. During this work, a patterned bottom structure with rigid backplate and cavity is fabricated directly by a 3D printing method, and then a direct write inkjet printing technique has been employed to print a silver conductive layer. A novel approach has been used to fabricate a diaphragm for the acoustic sensor as well, where the conductive layer is inkjet-printed on a pre-stressed thin organic film. After assembly, the resulting structure contains an electrically conductive diaphragm positioned at a distance from a fixed bottom electrode separated by a spacer. Measurements confirm that the transducer acts as capacitor. The deflection of the diaphragm in response to the incident acoustic single was observed by a laser Doppler vibrometer and the corresponding change of capacitance has been calculated, which is then compared with the numerical result. Observation confirms that the device performs as a resonator and provides adequate sensitivity and selectivity at its resonance frequency.

We are reporting energy scavenging from fluid flows inside tubular structures using triboelectric effects. Two separate designs of triboelectric generators are proposed. A tubular design that uses liquid-solid interaction mechanism for water, and freestanding flapping films design utilizing contact-separation mechanism for wind flow energies conversions. The developed generators exhibit capabilities to produces power from fluid motions through the tube. Osmotic water having conductivity of 2.05±0.05 μS/cm provides higher triboelectric responses in comparison to tap water (conductivity of 322.0±2.0 μS/cm) flow. An average power of 37.4 μW for an osmotic water flow of82.5±0.5 cm3/s was generated for two pairs of triboelectric generators. Under a wind flow of 8.2±0.1 m/s and using three pairs of generators an average power of 144.8 μW was obtained across an optimum load resistance (RL ) of 7.6 MΩ.

MEMS inductors are used in a wide range of applications in micro- and nanotechnology, including RF MEMS, sensors, power electronics, and Bio-MEMS. Fabrication technologies set the boundary conditions for inductor design and their electrical and mechanical performance. This review provides a comprehensive overview of state-of-the-art MEMS technologies for inductor fabrication, presents recent advances in 3D additive fabrication technologies, and discusses the challenges and opportunities of MEMS inductors for two emerging applications, namely, integrated power electronics and neurotechnologies. Among the four top-down MEMS fabrication approaches, 3D surface micromachining and through-substrate-via (TSV) fabrication technology have been intensively studied to fabricate 3D inductors such as solenoid and toroid in-substrate TSV inductors. While 3D inductors are preferred for their high-quality factor, high power density, and low parasitic capacitance, in-substrate TSV inductors offer an additional unique advantage for 3D system integration and efficient thermal dissipation. These features make in-substrate TSV inductors promising to achieve the ultimate goal of monolithically integrated power converters. From another perspective, 3D bottom-up additive techniques such as ice lithography have great potential for fabricating inductors with geometries and specifications that are very challenging to achieve with established MEMS technologies. Finally, we discuss inspiring and emerging research opportunities for MEMS inductors.