Controllable Fabrication of Percolative Metal Nanoparticle Arrays Applied for Quantum Conductance-Based Strain Sensors

Abstract

We use gas phase deposition of well-defined nanoparticles (NPs) to fabricate closely-spaced Pd NP arrays on flexible membranes prepatterned with interdigital electrodes (IDEs). The evolution of the morphology and electron conductance of the NP arrays during deposition is analyzed. The growth of two-dimensional percolation clusters of interconnected NPs, which correlate with the percolation pathway for electron conduction in the NP deposits, is demonstrated. The percolative nature of the NP arrays permits us to finely control the percolation geometries and conductance of the NP film by controlling the NP deposition time so as to realize a precise and reproducible fabrication of sensing materials. Electron transport measurements reveal that the electrical conductance of the NP films is dominated by electron tunneling or hopping across the NP percolating networks. Based on the percolative and quantum tunneling nature, the closely-spaced Pd NP films on PET membranes are used as flexible strain sensors. The sensor demonstrates an excellent response ability to distinguish tiny deformations down to 5×10−4 strain and a high sensitivity with a large gauge factor of 200 up to 4% applied strain.

Gas phase fabrication of morphology-controlled ITO nanoparticles and their assembled conductive films

“…Such temperature-dependent conductance is commonly observed in the closely spaced arrays of metallic nanoparticles, and the positive temperature coefficient of conductance indicates that electron tunneling and/or hopping dominates the transport in the film. 56 In such a system, the electron conductance is related to the number of percolative paths comprised of closely spaced nanoparticle chains. A TEM image of such percolative chains of closely contacted multi-branch ITO nanoparticles is shown in Fig.…”

A 3D Composited Flexible Sensor Based on Percolative Nanoparticle Arrays to Discriminate Coupled Pressure and Strain

“…In this paper, palladium (Pd) was used to create NP arrays because of its exceptional chemical stability [30]. The Pd NP arrays were generated from the gas aggregation source and deposited into the IDEs on both substrates [20,31], to fabricate the sensing elements (SEs) on the PET and PDMS. The schematic of the NPs deposition system is shown in Figure 1b.…”

“…In fact, the continuous deposition leads subsequent NPs to fill the insulating separation in the NP arrays, resulting in a gradual transformation of electronic transport from quantized tunneling/hopping to the classical flowing, which may degrade the sensitivities of the sensing elements to mechanical stimuli. Controlling the amount of NP deposition to ensure the quantized transport domaining the transport behavior in NP arrays, is much significant for the performance guarantee of the sensors [20]. We purchased silver particles and palladium target materials with a purity of 99.99% to vapor-deposit IDEs and deposit NP arrays, respectively.…”

“…Recently, some conducting nanoparticles (NPs) are assembled as percolative dense arrays to construct flexible sensing materials [18,19]. In these NP arrays, the electronic transport involving tunneling and hopping, is sensitive to the deformation of the sensing array, resulting in NP array-based sensors with the capability of detecting mechanical stimuli with ultrahigh sensitivities and resolutions as well as ultralow power consumption [20,21]. It is worth noting that the properties of sensors could be tailored by adjusting the size of particles, the array coverage, the deposition position, and even the geometric dimension of substrates.…”

Dewetting Process of Silver Thin Films and Its Application on Percolative Pressure Sensors with High Sensitivity

“…The device sensitivity is about ten times higher than that of devices with traditional metallic films. In addition, Du et al [ 23 ] employed a similar sputtering process to realize a strain sensing device based on chromium NPAs with a sensitivity this is about one hundred times higher than metallic- or semiconductor-based strain sensors. In [ 20 ], an ultrahigh sensitive piezoresistive pressure sensor with percolative dense metal NPs deposited on a flexible polyethylene terephthalate membrane was proposed.…”