A mechanical switch device made of a polyimide-coated microfibrillated cellulose sheet

Abstract

This paper covers innovative results on the development of an electrostatically actuated mechanical switch device made of a microfibrillated cellulose sheet coated with a thin polyimide layer. For microelectronic applications, biodegradable and biocompatible nanomaterials such as microfibrillated cellulose (MFC) have attracted attention. The studied MFC sheets reveal a fibrous-like morphology composed of cellulose nanofibres leading to a high surface roughness. Moreover, the porous microstructure and the hydrophilic nature of the MFC sheet induce poor dielectric properties. These shortcomings make MFC sheets relatively unsuitable for electronic applications. In order to overcome these drawbacks, both sides of the MFC sheet are coated with a thin polyimide layer, which greatly improves the dielectric properties, moisture sensitivity and sheet surface roughness. This new sheet is then patterned in order to be used as a substrate for the fabrication of a micromechanical switch. Gold electrodes are added onto the sheet for electrostatic actuation and switch detection. The pull-down voltage of this switch, defined as the actuation voltage needed to establish a contact between the free end of the cantilever beam and the substrate, is measured to be about 55 V.

Functionalized Polymers from Lignocellulosic Biomass: State of the Art

“…Although device response time is high compared to silica-based MEMS, the value is comparable to polymer-based mechanical switches. A theoretical model based on a free-clamped silicon MEMS switch fits these measurements, demonstrating standard behavior [115]. This device is inexpensive and, with a biodegradability ratio of 83%, eco-friendly.…”

“…The recent reviews of Siró et al [97], Lavoine et al [98] and Johansson et al [99] give an overview of these competitive nanomaterials. More recent applications also include materials for polyelectrolyte systems in batteries [100][101][102][103][104][105][106], ionic diodes [107], superoleophobic (oil-repellant) aerogels [108], superabsorbents [109], emulsion stabilizers [110,111], foaming agents [112], coatings [83], membranes [113], tissue engineering [114], and electrostatically actuated mechanical switch devices [115]. A number of these applications are described in more detail in the following sections.…”

“…MEMS are widely used for accelerometers (to measure seismic activity, machine motion/vibration, navigation), biochips and biosensors. Couderc et al [115] reported on an electrostatically actuated micromechanical switch device made of an MFC sheet coated with a thin polyimide layer. The MFC sheet was first patterned to enable its use as a substrate.…”

Multilayer films composed of conductive poly(3‐hydroxybutyrate)/carbon nanotubes bionanocomposites and a photoresponsive conducting polymer

“…In order to develop new electronic devices, it is therefore necessary to find innovative solutions to the eco-sustainability problem of materials as substates for circuits. [2][3][4] From the environmental point of view, matrices that can be obtained by plant renewable sources not in competition with the food chain are certainly the best solution; examples of these materials are thermoplastic polymers as polyhydroxyalkanoates, 5 which are obtained as high-molecular polymer chains by bacterial fermentation of agricultural wastes. The polyhydroxyalkanoates (PHA) family comprises the highly crystalline and thermomechanically resistant homopolymers of 3-hydroxybutyrate (PHB).…”

Reinforcing effect of carboxymethylated nanofibrillated cellulose powder on hydroxypropyl cellulose

“…Among all biopolymers, cellulose is the most abundant and combines high strength and stiffness with low density and biodegradability (Zadorecki and Michell 1989;Couderc et al 2009). Its inherent mechanical properties arise from b-1,4 linked glucopyranose chains, aligned into highly ordered (crystalline) domains by intra-and intermolecular hydrogen bonds.…”