In sensory neurons, mechanotransduction is sensitive, fast and requires mechanosensitive ion channels. Here we develop a new method to directly monitor mechanotransduction at defined regions of the ...cell-substrate interface. We show that molecular-scale (~13 nm) displacements are sufficient to gate mechanosensitive currents in mouse touch receptors. Using neurons from knockout mice, we show that displacement thresholds increase by one order of magnitude in the absence of stomatin-like protein 3 (STOML3). Piezo1 is the founding member of a class of mammalian stretch-activated ion channels, and we show that STOML3, but not other stomatin-domain proteins, brings the activation threshold for Piezo1 and Piezo2 currents down to ~10 nm. Structure-function experiments localize the Piezo modulatory activity of STOML3 to the stomatin domain, and higher-order scaffolds are a prerequisite for function. STOML3 is the first potent modulator of Piezo channels that tunes the sensitivity of mechanically gated channels to detect molecular-scale stimuli relevant for fine touch.
This work presents the development of a dual-rotor rotational electromagnetic energy harvesting (EH) generator and its power management system (PMS). The electromagnetic harvester is driven ...mechanically by pushing or pulling a shaft. By doing so, energy can be harvested in both directions. The PMS steps up the ac voltage of the EH system and converts it into a useful dc one utilizing a maximum power point tracking (MPPT) concept. The PMS together with EH system are tested and the experimental results for the full system are presented. The EH device generates a maximum output energy of <inline-formula> <tex-math notation="LaTeX">100~\mu \text{J} </tex-math></inline-formula> with a maximum open circuit voltage of 0.7 V. The PMS achieves an efficiency of 70% while providing <inline-formula> <tex-math notation="LaTeX">350~\mu \text{A} </tex-math></inline-formula> at its output.
From electronic devices to large-area electronics, from individual cells to skin substitutes, printing techniques are providing compelling applications in wide-ranging fields. Research has thus ...fueled the vision of a hybrid, printing platform to fabricate sensors/electronics and living engineered tissues simultaneously. Following this interest, we have fabricated interdigitated-electrode sensors (IDEs) by inkjet printing to monitor epithelial cell cultures. We have fabricated IDEs using flexible substrates with silver nanoparticles as a conductive element and SU-8 as the passivation layer. Our sensors are cytocompatible, have a topography that simulates microgrooves of 300 µm width and ~4 µm depth, and can be reused for cellular studies without detrimental in the electrical performance. To test the inkjet-printed sensors and demonstrate their potential use for monitoring laboratory-growth skin tissues, we have developed a real-time system and monitored label-free proliferation, migration, and detachment of keratinocytes by impedance spectroscopy. We have found that variations in the impedance correlate linearly to cell densities initially seeded and that the main component influencing the total impedance is the isolated effect of the cell membranes. Results obtained show that impedance can track cellular migration over the surface of the sensors, exhibiting a linear relationship with the standard method of image processing. Our results provide a useful approach for non-destructive in-situ monitoring of processes related to both in vitro epidermal models and wound healing with low-cost ink-jetted sensors. This type of flexible sensor as well as the impedance method are promising for the envisioned hybrid technology of 3D-bioprinted smart skin substitutes with built-in electronics.
Safety is a crucial issue in hydrogen energy applications due to the unique properties of hydrogen. Accordingly, a suitable hydrogen sensor for leakage detection must have at least high sensitivity ...and selectivity, rapid response/recovery, low power consumption and stable functionality, which requires further improvements on the available hydrogen sensors. In recent years, the mature development of nanomaterials engineering technologies, which facilitate the synthesis and modification of various materials, has opened up many possibilities for improving hydrogen sensing performance. Current research of hydrogen detection sensors based on both conservational and innovative materials are introduced in this review. This work mainly focuses on three material categories, i.e., transition metals, metal oxide semiconductors, and graphene and its derivatives. Different hydrogen sensing mechanisms, such as resistive, capacitive, optical and surface acoustic wave-based sensors, are also presented, and their sensing performances and influence based on different nanostructures and material combinations are compared and discussed, respectively. This review is concluded with a brief outlook and future development trends.
In this paper we present and discuss two innovative liquid-free SOI sensors for pressure measurements in harsh environments. The sensors are capable of measuring pressures at high temperatures. In ...both concepts media separation is realized using a steel membrane. The two concepts represent two different strategies for packaging of devices for use in harsh environments and at high temperatures. The first one is a "one-sensor-one-packaging_technology" concept. The second one uses a standard flip-chip bonding technique. The first sensor is a "floating-concept", capable of measuring pressures at temperatures up to 400 °C (constant load) with an accuracy of 0.25% Full Scale Output (FSO). A push rod (mounted onto the steel membrane) transfers the applied pressure directly to the center-boss membrane of the SOI-chip, which is placed on a ceramic carrier. The chip membrane is realized by Deep Reactive Ion Etching (DRIE or Bosch Process). A novel propertied chip housing employing a sliding sensor chip that is fixed during packaging by mechanical preloading via the push rod is used, thereby avoiding chip movement, and ensuring optimal push rod load transmission. The second sensor can be used up to 350 °C. The SOI chips consists of a beam with an integrated centre-boss with was realized using KOH structuring and DRIE. The SOI chip is not "floating" but bonded by using flip-chip technology. The fabricated SOI sensor chip has a bridge resistance of 3250 Ω. The realized sensor chip has a sensitivity of 18 mV/µm measured using a bridge current of 1 mA.
•Quantum capacitance becomes dominant with high-k ultra-thin dielectrics.•Quantum capacitance in Nanoribbons is influenced by Van-Hove singularities.•The transient mode in an armchair graphene ...nanoribbon field-effect transistor results in undulations.•An extended Verilog-A model was built to include the quantum capacitance influence.
Graphene Nanoribbons (GNRs) are an emerging candidate to challenge the place of current semiconductor-based technology. In this work, we extend a model for Armchair Graphene Nanoribbons Field-Effect Transistor (AGNRFET) to the high-k dielectrics realm and examine the influences of quantum capacitance on its transient phenomena. The model is coded with Verilog-A and evaluated through SPICE simulations. We have considered a comparison between the extended model with and without the influence of the quantum capacitance. Simulation results show a realistic scenario where influence of the quantum capacitance significantly impacts the transient behaviour in circuit design. This proves the proposed model to be a valuable aid for the circuit design of future graphene-based applications.
This article presents prime results on process development and optimization of dry etching of silicon carbide (SiC) for via formation and deep etching for SiC-based microsystems. The investigations ...and corresponding results of the process developments enable the first realization of a full SiC-based technological demonstrator composed of a SiC-interposer with a flip chip mounted deep etched micro electromechanical system (MEMS) SiC Device. By optimizing the process, etch depth of 200 <inline-formula> <tex-math notation="LaTeX">\mu \text{m} </tex-math></inline-formula> with an etch rate of up to 2 <inline-formula> <tex-math notation="LaTeX">\mu \text{m} </tex-math></inline-formula>/min can be achieved for via etching. In addition, a design of experiments (DoEs) with a total of 29 experiments with seven factors was done to characterize the deep etching of large areas into the SiC. Hereby, vertical sidewalls with low micromasking, low microtrenching and an etch rate of up to 4 <inline-formula> <tex-math notation="LaTeX">\mu \text{m} </tex-math></inline-formula>/min could be achieved. The findings and optimized processes were implemented to develop on the one hand a 200-<inline-formula> <tex-math notation="LaTeX">\mu \text{m} </tex-math></inline-formula>-thick SiC interposer with copper metallization. On the other hand, a SiC-MEMS Device was manufactured with a deep etched cavity in SiC bulk wafer forming by the end a 50-<inline-formula> <tex-math notation="LaTeX">\mu \text{m} </tex-math></inline-formula> thin membrane. The results demonstrate the ability of etching monocrystalline SiC with a high etch rate, enabling new fundamental topologies/structures and packaging concepts for harsh environments MEMSs and high-power electronics. The developed etching technologies demonstrate and enable various applications for 3-D Integration with wide bandgap substrates taking advantage of the superior electrical and mechanical properties of SiC.
A novel 4H SiC piezoresistive pressure sensor has been fabricated using a high temperature metallization system. The sensor has been fabricated using 100 mm 4H- SiC Wafers with an double EPI layer. ...While the top has been etched to form the piezoresistors, the lower Epi-layer is oppositely doped acts as an isolation layer. The formation of the membrane has been performed by a reactive ion etching (RIE) process enabling etch rates of up to 4 µm/min through bulk SiC. The gold-based metallization system is able to withstand high temperatures.
For the atmospheric pressure sputtering technology, directly structured thin- and highly conductive layers of platinum were additively deposited on Al2O3 ceramic substrate. The necessary process ...parameters could be identified and the layers could be contacted reliable by using thin-wire bonding. A subsequent storage for 1,000 h at 500°C shows no degeneration of the mechanical bonding properties.
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