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SiC based pressure sensors show tremendous promise for harsh environment applications thanks to their excellent mechanical, electrical, thermal, and chemical properties. This paper presents the design, fabrication, and characterisation of a highly sensitive and robust 3C-SiC/Si pressure sensor. The sensor utilises a stress amplification structure consisting of four Si pillars built up from the 3C-SiC/Si membrane, supporting a series of released n-type 3C-SiC sensing elements. When pressure is applied to the diaphragm, the pillars act to locally concentrate and amplify strain in the 3C-SiC sensing elements, resulting in over 7 times higher stresses/strains in these sensing elements compared to a traditional structure. Additionally, the front side of the sensor is fully covered by a 3C-SiC thin film, which provides a strong chemical protective capability, allowing the sensor to operate in harsh chemically corrosive environments. The robust device utilises the full Wheatstone bridge to negate the effects of temperature. Experimental results show that the fabricated sensor is highly stable, repeatable, has a high sensitivity of 0.276 mV/V/kPa and a maximum non-linearity of 2.2 % in the 0–100 kPa region. The results indicate that this smart-structure pressure sensor is promising for applications that require highly precise pressure sensing in aggressively corrosive environments.

Calcium phosphate (CaP) coating on melt electrowritten (MEW) substrates is a potential candidate for bone regeneration influencing the interaction of osteoblasts with implanted scaffolds. Pretreatment to improve hydrophilicity of the hydrophobic polymer fibres affects subsequent coating with bioactive compounds like CaP. Therefore, this study evaluated the subsequent stability and structural properties of CaP coated MEW Poly-ε-caprolactone (PCL) scaffolds following pre-treatment with either argon-oxygen plasma or sodium hydroxide (NaOH). Scanning electron microscopy and μ-CT showed uniform CaP coating after one hour immersion in simulated body fluid following plasma pretreatment. Moreover, fourier transform infrared spectroscopy, energy dispersive spectrometry and X-ray diffraction analysis confirmed the presence of hydroxyapatite, tetracalcium phosphate and halite structures on the coated scaffolds. Contact angle measurement showed that the plasma pretreatment and CaP coating improved the hydrophilicity of the scaffold. However, the mechanical properties of the scaffolds were degraded after both plasma and NaOH treatments. The tensile stability was significantly improved following mineralization in plasma-treated scaffolds due to the smaller crystal size formed on the surface resulting in a dense CaP layer. The results obtained by thermogravimetric analysis also confirmed higher deposition of CaP particles on coated scaffolds following plasma modification. The results of this study show that plasma pre-treated mineralized MEW PCL scaffolds are sufficiently stable to be useful for further development in bone regeneration applications. Keywords: Calcium phosphate coating, Polycaprolactone, Melt electrowriting, Apatite mineralization, Plasma treatment, Bone regeneration

E-skin with physical sensing capability has attracted considerable interest towards practical applications in soft robotics, human–machine interfaces, and wearable health monitoring. However, the development of a multimodal sensing platform with multiple layers for e-skin sensing of temperature and pressure has faced challenges due to the typical use of bare or single sensing layers as well as the complication of integration of multifunctional sensing modules onto curved surfaces. Herein, we demonstrate a new platform technology with multiple sandwiched layers of highly oriented carbon nanotube (CNT) films and polyacrylonitrile (PAN) for integration of pressure and temperature sensory functionalities into a single platform that is thin, ultra-lightweight, flexible, and wearable. The key technology of in-situ deposition of sensor platform on objects or in robot interface makes this a unique method for the development of e-skins for robotic applications, offering a new approach to wearable electronics and portable health care.

A flexible pressure sensor with a rudimentary, ultra-low cost, and solvent-free fabrication process is presented in this paper. The sensor has a graphite-on-paper stacked paper structure, which deforms and restores its shape when pressure is applied and released, showing an exceptionally fast response and relaxation time of ≈0.4 ms with a sensitivity of −5%/Pa. Repeatability of the sensor over 1000 cycles indicates an excellent long-term stability. The sensor demonstrated fast and reliable human touch interface, and successfully integrated into a robot gripper to detect grasping forces, showing high promise for use in robotics, human interface, and touch devices.

A piezoelectrically actuated valveless micropump has been designed and developed. The principle components of this system are piezoelectrically actuated (PZT) metal diaphragms and a complete fluid flow system. The design of this pump mainly focuses on a cross junction, which is generated by a nozzle jet attached to a pump chamber and the intersection of two inlet channels and an outlet channel respectively. During each PZT diaphragm vibration cycle, the junction connecting the inlet and outlet channels with the nozzle jet permits consistencies in fluidic momentum and resistances in order to facilitate complete fluidic path throughout the system, in the absence of any physical valves. The entire micropump structure is fabricated as a plate-by-plate element of polymethyl methacrylate (PMMA) sheets and sandwiched to get required fluidic network as well as the overall device. In order to identify the flow characteristics, and to validate the test results with numerical simulation data, FEM analysis using ANSYS was carried out and an eigenfrequency analysis was performed to the PZT diaphragm using COMSOL Multiphysics. In addition, the control system of the pump was designed and developed to change the applied frequency to the piezoelectric diaphragms. The experimental data revealed that the maximum flow rate is 31.15 mL/min at a frequency of 100 Hz. Our proposed design is not only for a specific application but also useful in a wide range of biomedical applications.

In this paper, we report on the design, simulation, and experimental analysis of a miniaturized device that can generate multiple circulated jet flows. The device is actuated by a lead zirconate titanate (PZT) diaphragm. The flows in the device were studied using three-dimensional transient numerical simulation with the programmable open source OpenFOAM and was comparable to the experimental result. Each flow is verified by two hotwires mounted at two positions inside each consisting chamber. The experiment confirmed that the flow was successfully created, and it demonstrated good agreement with the simulation. In addition, a prospective application of the device as an angular rate sensor is also demonstrated. The device is robust, is minimal in size, and can contribute to the development of multi-axis fluidic inertial sensors, fluidic amplifiers, gas mixing, coupling, and analysis.

This paper reports on the design and simulation of a valveless micro pump which promises widely applicable in microfluidic applications. The structure of the pump comprises a PZT diaphragm and a fluidic network channel which can be easily fabricated by either conventional machining or silicon micromachining techniques. The working principle of the pump relies on the structure of the cross junction which connects the pump chamber, the outlet and two opposite inlet channels. This design allows a difference of fluidic resistance and momentum between the pump phases which results in a net flow from the inlet to outlet. The pump performance is studied by numerical simulation by applying the deformation of the PZT diaphragm. Experiments of the prototype had been conducted and working principle was confirmed.

This paper reports a robust fabrication process to integrate carbon nanotubes (CNTs) film into a micro electromechanical systems actuator by the design and fabrication of a silicon micromirror supported by CNTs hinges. Vertically aligned single wall carbon nanotubes forest film was synthesized by water-assisted chemical vapor deposition. CNTs film was then condensed, manually maneuvered and patterned by EB lithography to form a flexible hinge of a mirror. The mirror is actuated by a electrostatic angular vertical comb actuator and the performance had been characterized. The mirror could be driven by a low voltage with a rotate angle of 1.5° and a response frequency of 500 Hz. [ABSTRACT FROM AUTHOR]

In this paper, we present the simulation and fabrication of the gas gyroscope. The gas flow inside the hermetically packed sensor is simulated by utilizing 3-D transient compressible flow analysis. The pump working principle and the effect of the Coriolis acceleration on the laminar jet are validated by both analytical formulas and experiments. The sensor utilizes a new sensing element consisting of a thermistor heated by an interior heater, which is independently power-supplied. The sensor performance can be adjusted by the applied voltage on the heater. Both heater and thermistor are optimized in terms of thermal stress. The effect of thermal stress in a p-type silicon thermistor reduces the performance of sensor by 9.5%. The sensor has been calibrated and the role of the heater is verified. [ABSTRACT FROM PUBLISHER]

This paper describes the design, simulation, and fabrication of a dual-axis gyroscope, whose working principle is based on the thermal convective and thermoresistive effects in lightly doped p-type silicon. The sensor configuration consists of a piezoelectric pump and a microthermal sensing element that is packaged in an aluminum case with a diameter of 14 mm and a length of 25 mm. The novel structure of the sensing element reduces the thermal-induced stress up to 89% as compared with the previous design. The sensor has been fabricated by micro-electromechanical systems technology, and completely packaged and characterized. The measured sensitivities of the gyroscope for the X-axis and Y-axis were 0.082 and 0.078 mV/°/s, respectively. The cross sensitivities between the two input axes were less than 0.26%, and the nonlinearity was smaller than 0.5% full scale in the range of ±200°/s. The resolution was 0.2°/s at a measurement frequency of 1 Hz. The noise equivalent rate was 0.18°/s/ √Hz, which is equivalent to an angle random walk of 10.8° / √/h in a 65-Hz bandwidth. The offset drift was 360°/h in 12-h measurement. [ABSTRACT FROM AUTHOR]

The paper reports the first study on the backpressure of a valveless electromagnetic micropump using the volume-of-fluid (VOF) technique and open-source code OpenFOAM. The micropump consists of a vibrating diaphragm and fluidic microchannel connected to inlet and outlet tubes. The imbalance in fluid resistance of the fluidic microchannel during a vibration cycle of the diaphragm creates backpressure in the pump, which in turn produces a difference in water level between the inlet and outlet tubes. In this study, VOF was used in a transient simulation to obtain this difference in water level and then the backpressure. The obtained backpressure showed a slight discrepancy with the experimental data. The discrepancy was probably due to the difference in the wall surface quality of the fluidic microchannel between the simulation model and experimental device. These results are useful for analytical and numerical research on these types of micropumps and can easily be applied in an open-source code simulator with almost zero cost. [ABSTRACT FROM AUTHOR]