Flexible-foam-based capacitive sensor arrays for object detection at low cost

Metzger, Christian; Fleisch, Elgar; Meyer, Jan Thomas; Dansachmüller, M.; Graz, Ingrid; Kaltenbrunner, Martin; Keplinger, Christoph; Schwödiauer, Reinhard; Bauer, Siegfried

doi:10.1063/1.2830815

Cited by 165 publications

(108 citation statements)

References 9 publications

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“…It is known that capacitive sensors achieve the highest precision of all electrical sensors, have simple and robust structures, feature high sensitivity and resolution, and allow long-term, drift-free sensing even when temperature changes. [25][26][27][28] We next derive the relation between deformation and capacitance. We adopt the model of ideal dielectric elastomers, assuming that the volume and permittivity remain constant as the elastomers deform.…”

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confidence: 99%

Ionic skin

et al. 2014

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Our skin is a stretchable, large-area sheet of distributed sensors. These properties of skin have inspired the development of mimics, with differing levels of sophistication, to enable wearable or implantable electronics for entertainment and healthcare. [1][2][3][4] "Electronic skin" is generally taken to be a stretchable sheet with area above 10 cm 2 carrying sensors for various stimuli, including deformation, pressure, light and temperature. The sensors report signals through stretchable electrical conductors [5] (e.g., carbon grease, [6] microcraked metal films, [1] serpentine metal lines, [2] graphene sheets, [7] carbon nanotubes, [8][9][10] silver nanowires, [11] gold nanomeshes, [12] and liquid metals [13,14] ). These conductors transmit signals using electrons.They meet the essential requirements of conductivity and stretchability, but struggle to meet additional requirements in specific applications, such as biocompatibility in biometric sensors, [15] and transparency in tunable optics. [16,17] By contrast, sensors in our skin report signals using ions. Here we explore the potential of ionic conductors in the development of a new type of sensory sheet, which we call "ionic skin".The sensory sheet is highly stretchable, transparent, and biocompatible. It readily monitors large deformation, such as that generated by the bending of a finger. It detects stimuli with wide dynamic range (strains from 1% to 500%). It measures pressure as low as 1 kPa, with small drift over many cycles. A sheet of distributed sensors covering a large area can report the location and pressure of touch. High transparency allows the sensory sheet to transmit electrical signals without impeding optical signals.Many ionic conductors, such as hydrogels and ionogels, are highly stretchable and transparent. [18][19][20] These gels are polymeric networks swollen with water or ionic liquids. They behave like elastic solids and eliminate the need for containers as required in the case of liquid metal conductors. Whereas familiar elastic gels, such as Jell-O, are brittle and easily rupture, the recent decade has seen the development of hydrogels and ionogels as tough as elastomers. [20][21][22] Many hydrogels are biocompatible. They can be made softer than tissues, achieving the "mechanical invisibility" required for biometric sensors, which monitor soft tissues without 3 constraining them. Although most hydrogels dry out in open air, hydrogels containing humectants retain water in environment of low humidity, and ionogels are nonvolatile in vacuum. [18][19][20] We have recently used ionic conductors-together with stretchable and transparent dielectrics-to make actuators, which deform in response to high voltages, on the order of kilovolts. [18] By contrast, the sensors described here deform in response to applied forces, giving signals that can be measured using voltages below 1 volt. To illustrate principles in our design of the ionic skin, consider a simple example-a dielectric sandwiched between two ionic conductors (Figure 1). In many...

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Ionic skin

et al. 2014

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“…However, the mechanical interaction between the AFM cantilever and the NW can harm the NW structure during the manipulation process; in addition, this technique is limited to the manipulation of a reduced number of NWs at the same time. The assembly of NWs through dielectrophoresis has attracted attention of researchers due to the ability of this technique to precisely position NWs at specific places on a substrate [21][22][23][24][25][26], making possible the fabrication of NW based applications including field effect transistors (FET) [27,28], biosensors [29], and other functional electronic devices [30]. Moreover, this approach allows to assemble NWs directly on flexible substrates and at large-areas which is promising for the development of flexible light-emitting diode (LED) displays [31], and transparent flexible nano-electronics [32].…”

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confidence: 99%

Photodetector fabrication by dielectrophoretic assembly of GaAs nanowires grown by a two-steps method

García-Núñez

Braña

López

et al. 2017

Optical Sensing, Imaging, and Photon Counting: Nanostructured Devices and Applications 2017

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GaAs nanowires (NWs) are promising advanced materials for the development of high performance photodetectors in the visible and infrared range. In this work, we optimize the epitaxial growth of GaAs NWs compared to conventional procedures, by introducing a novel two-steps growth method that exhibits an improvement of the resulting NW aspectratio and an enhancement of the NW growth rate. Moreover, we investigate the contactless manipulation of NWs using non-uniform electric fields to assemble a single GaAs NW on conductive electrodes, resulting in assembly yields above 90%/site and an alignment yields of around 95%. The electrical characteristics of the dielectrophoretic contact formed between the NW and the electrode have been measured, observing that the use of n-type Al-doped ZnO (AZO) as electrode material for NW alignment produces Schottky barrier contacts with the GaAs NW body. Moreover, our results show the fast fabrication of diodes with rectifying characteristics due to the formation of a low-resistance contact between the Ga catalytic droplet at the tip of the NW and the AZO electrode. The current-voltage measurements of a single GaAs NW diode under different illumination conditions show a strong light responsivity of the forward bias characteristic mainly produced by a change on the series resistance.

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“…[1][2][3][4][5][6][7][8] High sensitivity, chemical and thermal stability, non-toxicity, mechanical compliance and bio-compatibility have led to the way for energy-efficient implantable electronic devices. 9,10 Advances in electronics have paved the way for the adoption of many different types of photodetectors, sensors by using different materials in individual or with their combination. [11][12][13][14][15][16][17][18] Meanwhile, important research reports have been published on the versatile use of graphene and its derivatives and on carbon nanoparticles.…”

Section: Introductionmentioning

confidence: 99%

Graphene oxide/carbon nanoparticle thin film based IR detector: Surface properties and device characterization

et al. 2015

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This work deals with the synthesis, characterization, and application of carbon nanoparticles (CNP) adorned graphene oxide (GO) nanocomposite materials. Here we mainly focus on an emerging topic in modern research field presenting GO-CNP nanocomposite as a infrared (IR) radiation detector device. GO-CNP thin film devices were fabricated from liquid phase at ambient condition where no modifying treatments were necessary. It works with no cooling treatment and also for stationary objects. A sharp response of human body IR radiation was detected with time constants of 3 and 36 sec and radiation responsivity was 3 mAW−1. The current also rises for quite a long time before saturation. This work discusses state-of-the-art material developing technique based on near-infrared photon absorption and their use in field deployable instrument for real-world applications. GO-CNP-based thin solid composite films also offer its potentiality to be utilized as p-type absorber material in thin film solar cell, as well.

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Flexible-foam-based capacitive sensor arrays for object detection at low cost

Cited by 165 publications

References 9 publications

Ionic skin

Ionic skin

Photodetector fabrication by dielectrophoretic assembly of GaAs nanowires grown by a two-steps method

Graphene oxide/carbon nanoparticle thin film based IR detector: Surface properties and device characterization

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