Structural health monitoring of civil infrastructures is a difficult task, often impeded by the geometrical size of the monitored systems. Recent advances in conducting polymers enabled the fabrication of flexible sensors capable of covering large areas, a possible solution to the monitoring challenge of mesoscale systems. The authors have previously proposed a novel sensor consisting of a soft elastomeric capacitor (SEC) acting as a strain gauge. Arranged in a network configuration, the SECs have the potential to cover very large surfaces. In this paper, understanding of the proposed sensor is furthered by evaluating its performance at vibration-based monitoring of large-scale structures. The dynamic behavior of the SEC is characterized by subjecting the sensor to a frequency sweep, and detecting vibration modes of a full-scale steel beam. Results show that the sensor can be used to detect fundamental modes and dynamic input. Also, a network of SECs is used for output-only modal identification of a full-scale concrete beam, and results are benchmarked against off-theshelf accelerometers. The SEC network performs well at estimating both natural frequencies and mode shapes. The resolution of the sensor is currently limited by the available electronics to measure small changes in capacitance, which reduces its accuracy with increasing frequencies in both the time and frequency domain. The authors have previously proposed a novel sensor consisting of a soft elastomeric capacitor (SEC) acting 8 as a strain gauge. Arranged in a network configuration, the SECs have the potential to cover very large 9 surfaces. In this paper, we further the understanding of the proposed sensor by evaluating its performance at 12show that the sensor can be used to detect fundamental modes and dynamic input. Also, a network of

The authors have recently developed two novel solutions for strain sensing using nanocomposite materials. While they both aim at providing cost-effective solutions for the monitoring of local information on largescale structures, the technologies are different in their applications and physical principles. One sensor is made of a cementitious material, which could make it suitable for embedding within the core of concrete structures prior to casting, and is a resistor, consisting of a carbon nanotube cement-based transducer. The other sensor can be used to create an external sensing skin and is a capacitor, consisting of a flexible conducting elastomer fabricated from a nanocomposite mix, and deployable in a network setup to cover large structural surfaces. In this paper, we advance the understanding of nanocomposite sensing technologies by investigating the potential of both novel sensors for the dynamic monitoring of civil structures. First, an indepth dynamic characterization of the sensors using a uniaxial test machine is conducted. Second, their performance at dynamic monitoring of a full-scale concrete beam is assessed, and compared against off-theshelf accelerometers. Experimental results show that both novel technologies compare well against mature sensors at vibration-based structural health monitoring, showing the promise of nanocomposite technologies for the monitoring of large-scale structural systems. The authors have recently developed two novel solutions for strain sensing using nanocomposite materials. While they both aim at providing cost-eective solutions at monitoring local information on large-scale structures, both technologies are dierent in their applications and physical principles. One sensor is made of a cementitious material, which could make it suitable for embedding within the core of concrete structures prior to casting, and is a resistor, consisting of a carbon nanotube-cement based transducer. The other sensor can be used to create an external sensing skin and is a capacitor, consisting of a exible conducting elastomer fabricated from a nanocomposite mix, and deployable in a network setup to cover large structural surfaces. In this paper, we advance the understanding of nanocomposite sensing technologies by investigating the potential of both novel sensors at dynamic monitoring of civil structures. First, an in-depth dynamic characterization of the sensors using a uniaxial test machine is conducted. Second, their performance at dynamic monitoring of a full-scale concrete beam is assessed, and compared against othe-shelf accelerometers. Experimental results show that both novel technologies compare well against mature sensors at vibration-based structural health monitoring, showing the promise of nanocomposite technologies at monitoring large-scale structural systems.

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nonconventional substrates (e.g., paper, tape, and cloth) [7][8][9][10] have been widely utilized as the base materials of flexible electronic devices. Conductive nanomaterials, such as carbon nanotubes, metal oxide nanowires, and graphene, have also attracted considerable attention as functional materials for applications ranging from transistors, to sensors, to energy harvesting and storage devices. [11][12][13][14][15][16][17][18][19][20][21][22] Among these conductive nanomaterials, graphene plays a key role in producing next-generation sensors owing to its unique properties, including atomic thickness, large surface area, fast electron mobility, good piezoresistivity, and high mechanical flexibility. [23][24][25][26][27] As a result, integrations between flexible substrate materials and graphene-based nanomaterials have led to a variety of sensors and other electronic devices through development of novel fabrication processes, advancing emerging and significant fields such as real-time motion tracking, [28] structural and human health monitoring, [29][30][31] electronic skin sensing, [32][33][34][35][36] and humanized robotic manipulation. [37] It is well known that repeated mechanical exfoliation to peel single-or few-layer graphene from bulk graphite using sticky tape and transfer it to another surface is rather uncontrollable in terms of the number of graphene layers, location, and size of the peeled graphene. [38] Recently, graphene film electrodes at centimeter scale have been fabricated by peeling tape from a commercial graphite foil for the detection of glucose, [39] but the obtained electrodes did not have well-defined shapes or control over thickness. Physically rubbed graphene electrodes have also been produced by directly placing solid-state graphene powders at a channeled adhesive surface and then rubbing against the surface. [40] The resulting graphene patterns, however, have poor feature resolution. Photolithography-based microfabrication for graphene patterning [41][42][43][44][45][46][47][48][49] is relatively complex and requires multiple steps such as film deposition, lithography, and etching. Recently, various interesting methods have been developed for patterning and transferring graphene-based materials onto different substrates. For example, laser printing of graphene has been studied with variable laser energy, spot size, and pulse duration. [50][51][52][53][54] This method, however, requires sophisticated lasers and is limited to producing patterns with minimum feature size of several tens of micrometers. An ink-jet printing This paper reports on a simple and versatile method for patterning and transferring graphene-based nanomaterials onto various types of tape to realize flexible microscale sensors. The method involves drop-casting a graphene film on a prepatterned polydimethylsiloxane (PDMS) surface containing negative features by graphene suspensions, applying Scotch tape to remove the excess graphene from the nonpatterned areas of the PDMS surface, and then transferring the patte...