A wearable, highly stable, strain and bending sensor based on high aspect ratio graphite nanobelts

Abstract

A simple and scalable method was developed for the fabrication of wearable strain and bending sensors, based on high aspect ratio (length/thickness ∼10(3)) graphite nanobelt thin films deposited by a modified Langmuir-Blodgett technique onto flexible polymer substrates. The sensing mechanism is based on the changes in contact resistance between individual nanobelts upon substrate deformation. Very high sensor response stability for more than 5000 strain-release cycles and a device power consumption as low as 1 nW were achieved. The device maximum stretchability is limited by the metal electrodes and the polymer substrate; the maximum strain that could be applied to the polymer used in this work was 40%. Bending tests carried out for various radii of curvature demonstrated distinct sensor responses for positive and negative curvatures. The graphite nanobelt thin flexible films were successfully tested for acoustic vibration and heartbeat sensing.

Graphite nanobelts characterization and application for blood pulse sensing

“…5b). Previous results obtained with this sensor configuration [23] demonstrated its high sensitivity for bending. Therefore, this sensor can be employed for cardiorespiratory signal monitoring, when attached to the skin surface subject to curvature variation during both blood circulation in arteries and breathing.…”

“…For deposition of thin films based on GNBs onto different substrates, the nanobelts were first suspended in N-Methyl-2-pyrrolidone (Sigma Aldrich) solutions using an ultrasonic bath (Unique USC-1880, 100 W, 37 kHz) and then deposited using a modified Langmuir-Blodgett (LB) method with a special trapezoidal cuvette [11,23]. For detailed electrical characterization of GNBs based films, depositions were done over thermally oxidized Si substrates (SiO 2 thickness of ∼300 nm) with an active area of 7 Â 7 mm 2 .…”

Simple and Fast Approach for Synthesis of Reduced Graphene Oxide–MoS2 Hybrids for Room Temperature Gas Detection

“…The resistance of the material between electrodes was measured to be near 20 and its resistivity near 4 · cm. Second, a thin-film sensor was prepared by drop casting of isopropyl alcohol solution containing the powder between two parallel thin-film graphite electrodes (width of 10 mm, the gap between electrodes 1 mm) formed over a flexible polydimethylsiloxane support using the Langmuir-Blodgett method [43]. An estimated average thickness of the rGO-MoS 2 layer after drying was near 0.01 mm, and the sensor resistance was measured to be 10 k .…”

Growth of GaAs nanowire–graphite nanoplatelet hybrid structures

“…Meanwhile, almost no attention was attracted to the NW growth on graphite nanoplatelets (GNPs). GNPs are low defect graphitic surfaces with lateral sizes of few microns and thickness of tens of monolayers (MLs) which can be deposited on almost any substrate, including silicon, without complex processing with coverage up to centimeter range or more [22][23][24][25] . Such nanomaterials are attractive due to their planar structure, lightweight, high aspect ratio, electrical conductivity, low cost, mechanical toughness.…”