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Abstract

Nano energetic materials offer improved performance in energy release, ignition, and mechanical properties compared to their bulk or micro counterparts. In this study, the authors propose an approach to synthesize an Al/NiO based nano energetic material which is fully compatible with a microsystem. A two-dimensional NiO nano honeycomb is first realized by thermal oxidation of a Ni thin film deposited onto a silicon substrate by thermal evaporation. Then the NiO nano honeycomb is integrated with an Al that is deposited by thermal evaporation to realize an Al/NiO based nano energetic material. This approach has several advantages over previous investigations, such as lower ignition temperature, enhanced interfacial contact area, reduced impurities and Al oxidation, tailored dimensions, and easier integration into a microsystem to realize functional devices. The synthesized Al/NiO based nano energetic material is characterized by scanning electron microscopy, X-ray diffraction, differential thermal analysis, and differential scanning calorimetry.

Mots-Clés / Keywords

Pure; Aligned; CuO nanowire; Copper thin film; Silicon; N2/O2 gas flow;

Abstract

The present article describes the elaboration of a microactuator based on the decomposition of an energetic material. The fabrication of such a pyrotechnic actuator relies on novel smart materials and a simplified process developed through chemistry. The heterometallic Werner complex [Co(NH3)6]2[Mn(NO3)4]3 was chosen as an energetic material releasing only biocompatible gases when ignited. It was deposited on a resistance at the bottom of a micrometer scale chamber comprising directly photocurable polydimethylsiloxane walls and a thin elastic membrane as a roof. The membrane also comprised polysiloxanes. One of the key steps consisted of the grafting of siloxane-bearing acrylate moieties onto a standard silicon wafer, similar to those incorporated on the polysiloxane. The grafting was successfully characterized by XPS. Moreover, the walls of the cavity were elaborated by direct photolithography. After deposition of the energetic material, the cavity was sealed thanks to membrane grafting and the process was optimized to afford strong wafer/wall and wall/membrane interfaces in order to withstand the high mechanical stress imposed on the device in use.

Mots-Clés / Keywords

PDMS; Micro actuator; Energetic material; Photolithography;

Abstract

A microactuator consisting of an inflatable elastic membrane based on the decomposition of a small mass of energetic material deposited on a silicon microstructured platform is presented for disposable lab-on-a-chip applications. The energetic-material-based actuator is characterized by its small size (<0.25 mm2 × 100 µm), bio-compatibility and capability of generating sufficient overpressures (>10 kPa) under low electrical power (<100 mW) to eject a few nanolitres of fluid. This device has been fabricated using MEMS and microfluidic-compatible technology. The characterization of the actuation gave a pressurization of 13 kPa and a membrane deformation of 46 µm for an electrical initial power of 90 mW (6.5 V, 13.9 mA). All these characteristics make such a microactuator well adapted for microfluidic applications and especially for the ejection of fluids contained in micro-channels of a disposable lab-on-a-chip.

Mots-Clés / Keywords

MEMS; Microfluidics; Microfabrication; Micro actuator; Elastic polymer; Energetic material; Transition metals;

Abstract

Two-dimensional nanostructures have various interesting applications due to their large surface areas. In this study, we propose a simple approach to synthesize two-dimensional NiO nano honeycomb by thermal annealing of Ni thin film deposited onto silicon substrate by thermal evaporation. The effects on the nano honeycomb morphology of the annealing temperature and time are investigated. Because the NiO nano honeycomb is realized onto silicon substrate, a basic material for microelectronics and micro-system, this will probably open the door to integrate the nano honeycomb into micro-system, thus leading to nano based functional devices. The as-synthesized NiO nano honeycomb is characterized by SEM, XRD, and surface area measurement.

Mots-Clés / Keywords

Annealing; Ni thin film; Silicon substrate; Surface area; Nano NiO honeycomb;

Abstract

Vibration harvesting has been intensively developed recently and systems have been simulated and realized, but real-life situations (including aircraft Structure Health Monitoring (SHM) involve uneven, low amplitude, low frequency vibrations. In such an unfavorable case, it is very likely that no power can be harvested for a long time. To overcome this, multi-source harvesting is a relevant solution, and in our application both solar and thermal gradient sources are available. We propose in this paper a complete Microsystem including a piezoelectric vibration harvesting module, thermoelectric conversion module, signal processing electronics and supercapacitor. A model is proposed for these elements and a VHDL-AMS simulation of the whole system is presented, showing that the vibration harvesting device alone cannot supply properly a SHM wireless node. Its role is nevertheless important since it is a more reliable source than thermoelectric generators (which depends on climatic conditions). Moreover, synergies between vibration harvesting and thermoelectric scavenging circuits are presented.

Mots-Clés / Keywords

SHM; Energy harversting; Scavenging; Piezoelectric; Thermoelectric; Supercapacitor; VHDL-AMS; Simulation; MEMS;

Mots-Clés / Keywords

Energy harversting; MEMS; FEM modeling; PZT;