Graphene ribbons with suspended masses as transducers in ultra-small nanoelectromechanical accelerometers

Abstract

Nanoelectromechanical system (NEMS) sensors and actuators could be of use in the development of next generation mobile, wearable, and implantable devices. However, these NEMS devices require transducers that are ultra-small, sensitive and can be fabricated at low cost. Here, we show that suspended double-layer graphene ribbons with attached silicon proof masses can be used as combined spring-mass and piezoresistive transducers. The transducers, which are realized using processes that are compatible with large-scale semiconductor manufacturing technologies, can yield NEMS accelerometers that occupy at least two orders of magnitude smaller die area than conventional state-of-the-art silicon accelerometers. With our devices, we also extract the Young's modulus values of double-layer graphene and show that the graphene ribbons have significant built-in stresses.

Nanoelectromechanical Sensors Based on Suspended 2D Materials

“…In general, due to differences in fabrication and characterization procedures, large variations in the different material properties are found in literature, which leaves many open questions for NEMS device functionality. In addition, built-in stress in suspended 2D materials is generally large and difficult to control, while having a tangible influence on the static and dynamic characteristics of 2D material NEMS [ 72 ]. Built-in stress in fully clamped graphene membranes can reach 10 2 to 10 3 MPa [ 17 , 20 , 38 , 73 – 78 ] while stress in doubly clamped graphene ribbons or beams can reach 10 1 MPa [ 7 , 79 – 83 ] or about 200 MPa to 400 MPa in graphene ribbons with suspended silicon proof mass [ 72 ].…”

“…In addition, built-in stress in suspended 2D materials is generally large and difficult to control, while having a tangible influence on the static and dynamic characteristics of 2D material NEMS [ 72 ]. Built-in stress in fully clamped graphene membranes can reach 10 2 to 10 3 MPa [ 17 , 20 , 38 , 73 – 78 ] while stress in doubly clamped graphene ribbons or beams can reach 10 1 MPa [ 7 , 79 – 83 ] or about 200 MPa to 400 MPa in graphene ribbons with suspended silicon proof mass [ 72 ]. The built-in stress can substantially influence the resonance frequencies of resonators and accelerometers, as well as the force-induced deflection and strain in suspended 2D material membranes [ 72 ].…”

“…Ultrasound detector: (a) fabrication of the suspended membrane; (h) example device[181] and (i),(j) working principle: the graphene membrane is moved by the ultrasound induced motion of its supports, and its motion is detected using transconductance readout. Accelerometer: (k) fabrication of the suspended membrane; (l),(m) example device[72], (n)-(p) working principle: the acceleration induced forces on the suspended mass cause tension in the graphene that is detected using the piezoresistive effect. (q) The output signal of an accelerometer[72].…”

Engineering the Dissipation of Crystalline Micromechanical Resonators

“…5(c), is obtained from fitting the four parameters Q vol def , Q surf def , Q vol hq and Q surf hq to the model in Eq. (5). The surface component of the quality factor is assumed to follow a linear trend for trampoline resonators, as has been shown for silicon nitride membranes and microcantilevers [21,39].…”

Suspended Graphene Membranes with Attached Silicon Proof Masses as Piezoresistive Nanoelectromechanical Systems Accelerometers

“…Recently, graphene ribbons with suspended silicon proof masses have been utilized as piezoresistive electromechanical transducers in NEMS accelerometers with direct electrical readout. 46 In these devices, an acceleration force acting on the proof mass caused a deflection of the mass. This in turn caused a change of the strain in the suspended graphene ribbons, resulting in a change of the electrical resistances of the graphene ribbons because of the piezoresistivity of graphene.…”