KR20160105171A - Transparent and Stretchable Motion Sensor and Process for Preparing the Same - Google Patents

Abstract

The present invention relates to a transparent and stretchable motion sensor, and a manufacturing method thereof. More specifically, the present invention relates to a transparent and stretchable motion sensor which comprises: a first protective layer; a first electrode layer formed by being adjacent to the first protective layer; a piezoelectric layer formed by being adjacent to the first electrode layer; a second electrode layer formed by being adjacent to the piezoelectric layer; and a second protective layer formed by being adjacent to the second electrode layer.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a motion sensor and a method for manufacturing the same. 2. Description of the Related Art Transparent and Stretchable Motion Sensor and Process for Preparing the Same [

The present invention relates to a transparent and stretchable motion sensor and a method of manufacturing the same. More particularly, the present invention relates to a protective layer comprising: a first protective layer; A first electrode layer formed adjacent to the first passivation layer; A piezoelectric layer formed adjacent to the first electrode layer; A second electrode layer formed adjacent to the piezoelectric layer; And a second protective layer formed adjacent to the second electrode layer, and a method of manufacturing the same.

A wearable interactive human machine interface (iHMI) system is particularly well suited for use with smart glasses (Feng, S., et al . Immunochromatographic diagnostic assay using google glass, ACS Nano 8, 3069-3079 (2014)) and a timepiece (Wile, DJ, Ranawaya, R. , Kiss, ZHT Smart watch accelerometry for analysis and diagnosis of tremor, J. Neurosci. Methods 230, 1-4 (2014)) Has recently been attracting attention with the recent development of wearable electronic devices.

Wearable devices incorporating robust sensors and actuators offer high performance and practicality, but inconveniences arise from mechanical incompatibility between the human body and bulky rigid devices (Kim, D.-H., et al . Epidermal Electronics. Science 333 , 838-843 (2011) (Son, D., et al . Multifunctional wearable devices for diagnosis and therapy of movement disorders. Nat . Nanotech . 9 , 397-404 (2014) (Jeong, J.-W., et al . Materials and optimized designs for human-machine interfaces via epidermal electronics. Adv. Mater . 25 , 68396846 (2013)); Due to the design irreversibility of rugged electronics (Reuss, RH, et al . Macroelectronics: perspectives on technology and applications, Proc. IEEE , 93 , 1239-1256 (2005)), An unnatural appearance of the wearer due to design misalignment; And signal artefacts due to the nonconformal attachment of the robust sensor to the human body (Kim, D.-H., et al . Epidermal Electronics. Science 333 , 838-843 (2011) (Son, D., et al . Multifunctional wearable devices for diagnosis and therapy of movement disorders. Nat . Nanotech . 9 , 397-404 (2014) (Jeong, J.-W., et al . Materials and optimized designs for human-machine interfaces via epidermal electronics. Adv . Mater . 25 , 68396846 (2013)).

Therefore, there is a need for a new device that is conformally laminated to human skin to have a natural appearance and a high signal-to-noise ratio (SNR).

The adoption of a flexible and stretchable design and subsequent reduction in thickness and weight of the device is an important goal with respect to wearable electronic device design.

Recently, a flexible inorganic electronic device (Kim, D.-H., et al . Epidermal Electronics. Science 333 , 838-843 (2011) (Son, D., et al . Multifunctional wearable devices for diagnosis and therapy of movement disorders. Nat . Nanotech . 9 , 397-404 (2014) (Webb, RC, et al . Ultrathin conformal devices for precise and continuous thermal characterization of human skin. Nat . Mater . 12 , 938-944 (2013)), ultra-light and lightweight organic sensors (Someya, T., et al . Conformable, flexible, large-area networks of pressure and thermal sensors with organic transistor active matrixes. Proc . Natl . Acad . Sci . USA 102, 12321-12325 (2005) ( Sekitani, T., Zchieschang, U., Klauk, H., Someya, T. Flexible organic transistors and circuits with extreme bending stability. Nat. Mater. 9, 1015-1022 (2010 ), flexible electronics skin (Takei, K., et al. Nanowire active-matrix circuitry for low-voltage artificial skin macroscale. Nat. Mater. 9, 821-826 (2010) (Wang, C., et al . User-interactive electronic skin for instantaneous pressure visualization. Nat . Mater . 12, 899-904 (2013), and highly sensitive and flexible mechanical sensor (Mannsfeld, SCB, et al. Highly sensitive flexible pressure sensors with microstructured rubber dielectric layers. Nat. Mater. 9, 859-864 (2010)) (Lipomi, DJ, meat al . Skin-like pressure and strain sensors based on transparent elastic films of carbon nanotubes. Nat . Nanotech . 6 , 788-792 (2011)) (Jung, S., et al . Reverse-Micelle-Induced Porous Pressure-Sensitive Rubber for Wearable HumanMachine Interfaces. Adv Mater. Early View (2014)) (Gong, S, et al . A wearable and highly sensitive pressure sensor with ultrathin gold nanowires. Nat. Comm, 5 , 3132 (2014)).

The ultra-thin, deformable design allows accurate data collection from the human body with minimal signal noise. However, these previously reported devices are made of opaque semiconductors and metals and appear different from human skin. In addition, most of these sensors consume large amounts of power and thus require large power supplies (Kim, D.-H., et al., Epidermal Electronics Science 333 , 838-843 (2011) D., et al . Multifunctional wearable devices for diagnosis and therapy of movement disorders. Nat . Nanotech . 9 , 397-404 (2014) (Jeong, J.-W., et al . Materials and optimized designs for human-machine interfaces via epidermal electronics. Adv. Mater . 25 , 68396846 (2013)).

Transparent electronic materials can make the wearable device invisible, creating a natural look and enhanced aesthetics.

For example, carbon-based nanomaterials (Grafin (Kim, KS , et al . Large-scale pattern growth of graphene films for stretchable transparent electrodes. Nature 457 , 706-710 (2009)) and carbon nanotubes (Wu, Z. , et al . Transparent, conductive carbon nanotube films. Science , Vol. 87 , 1273-1276 (2004)) and metal nanowires (NW) (Hu, L., Kim, HS, Lee, J.-Y., Peumans, P., Cui, Y., meat al . Scalable coatings and properties of transparent, flexible, silver nanowire electrodes. ACS Nano 4 , 2955-2963 (2010)) and gold nanowires (Moraq, A., Ezersky, V., Froumin, N., Moqiliansky, D., Jelinek, R., Transparent, conductive gold nanowire networks assembled from soluble Au thiocyanate. Chem. Comm ., 49 , 8552-8554 (2013))) have been intensively studied.

Such transparent nanomaterials can be used in flexible electronic devices because they dramatically reduce the bending strength of nanoscale structures (Son, D., et al . Multifunctional wearable devices for diagnosis and therapy of movement disorders. Nat . Nanotech . 9 , 397-404 (2014)) (Rogers, J., Lagally, MG, Nuzzo, RG, Synthesis, Assembly and Applications of Semiconductor Nanomembranes, Nature 477 , 45-53 (2011)).

On the other hand, self-powered mechanical sensors based on piezoelectric materials can reduce the power dissipation of electronic systems (Xu, S., et al., Self-powered nanowire devices, 5 , 366-373 2010).

Poly (vinylidene chloride) (Lee, M. , et al . A hybrid piezoelectric structure for wearable nanogenerators. Adv . Mater . 24, 1759-1764 (2012)) ( Persano, L., et al. High performance piezoelectric devices based on aligned arrays of nanofibers of poly (vinylidenefluoride-co-trifluoroethylene). Nat. Comm. 4, 1633 (2013)) and Polylactic acid (PLA) (Yoshida, T. , et al . In this paper, we propose a new type of chiral polymer film. Jpn . J. Appl . Phys . 50 , 09ND13-1-09ND13-5 (2011)), and zinc oxide (Wang, ZL, Song, J., Piezoelectric nanogenerators based on zinc oxide nanowire arrays. Science 312 , 242-246 (2006) And lead zirconate titanate (Qi, Y. , et al . Enhanced piezoelectricity and stretchability in energy harvesting devices fabricated from buckled PZT ribbons. Nano Lett . 11 , 1331-1336 (2011)), a wide variety of piezoelectric materials have been studied.

A basic object of the present invention is to provide a protective layer comprising: a first protective layer; A first electrode layer formed adjacent to the first passivation layer; A piezoelectric layer formed adjacent to the first electrode layer; A second electrode layer formed adjacent to the piezoelectric layer; And a second protective layer formed adjacent to the second electrode layer.

Still another object of the present invention is to provide a method of manufacturing a PLA / SWNT composite film, comprising: (i) drop casting a dispersion of polylactic acid (PLA) and a single wall carbon nanotube (SWNT) (ii) spin-coating polymethylmethacrylate (PMMA) on a graphene sheet to prepare a graphene / PMMA film; And (ii) transferring the graphene / PMMA film to both sides of the PLA / SWNT composite film.

The basic object of the present invention described above is to provide a protective layer comprising: a first protective layer; A first electrode layer formed adjacent to the first passivation layer; A piezoelectric layer formed adjacent to the first electrode layer; A second electrode layer formed adjacent to the piezoelectric layer; And a second protective layer formed adjacent to the second electrode layer.

In the transparent and stretchable motion sensor of the present invention, the first protective layer may be polymethyl methacrylate (PMMA) or polylactic acid (PLA). The thickness of the first protective layer may be 50 nm to 100 탆.

In the transparent and stretchable motion sensor of the present invention, the first electrode layer may be graphene, single wall carbon nanotube (SWNT) or silver nanowire (AgNW). Moreover, the graphene may be graphene doped with gold. The thickness of the first electrode layer may be 1 nm to 100 nm.

In the transparent and stretchable motion sensor of the present invention, the piezoelectric layer may be a polylactic acid / single walled carbon nanotube (PLA / SWNT) composite film. In addition, the size of the single-walled carbon nanotube may be 50 nm to 1 mm. The thickness of the piezoelectric layer may be 100 nm to 500 m.

In the transparent and stretchable motion sensor of the present invention, the second electrode layer may be graphene, single wall carbon nanotube (SWNT) or silver nanowire (AgNW). Moreover, the graphene may be graphene doped with gold. The thickness of the second electrode layer may be 1 nm to 100 nm.

In the transparent and stretchable motion sensor of the present invention, the second protective layer may be polymethylmethacrylate (PMMA) or polylactic acid (PLA). In addition, the thickness of the second protective layer may be 50 nm to 100 탆.

In the transparent and stretchable motion sensor of the present invention, the first protective layer, the first electrode layer, the piezoelectric layer, the second electrode layer, and the second protective layer may be patterned in a serpentine pattern. When patterned in this way, it is well adhered to the skin and well behaves like bending or stretching of the body.

Still another object of the present invention is to provide a method of manufacturing a PLA / SWNT composite film, comprising: (i) drop casting a dispersion of polylactic acid (PLA) and a single wall carbon nanotube (SWNT) (ii) spin-coating polymethylmethacrylate (PMMA) on a graphene sheet to prepare a graphene / PMMA film; And (ii) transferring the graphene / PMMA film to both sides of the PLA / SWNT composite film.

In the transparent and stretchable motion sensor manufacturing method of the present invention, the thickness of the PLA / SWNT composite film is 100 nm to 500 μm, the thickness of the graphene layer in the graphene / PMMA film is 1 nm to 100 nm, In a graphene / PMMA film, the thickness of the PMMA layer may be 50 nm to 100 μm.

The transparent and stretchable motion sensor of the present invention can be conformally attached to human skin and does not fall off well, thus allowing the signal to be collected with minimal noise. In addition, due to the transparency of the motion sensor of the present invention, the user can be esthetically good when worn.

1 shows a process of fabricating a piezoelectric graphene heterostructure for a motion sensor of the present invention.
2 is a photograph of a transparent piezoelectric motion sensor of the present invention conformally contacting an upper part of a human wrist;
Fig. 3 is a photograph in which a part of the transparent piezoelectric motion sensor of the present invention is peeled off.
4 is a developed view of a patterned graphene (GP) heterostructure used in the motion sensor of the present invention.
5 is a scanning electron microscope (SEM) photograph (PMMA / graphene: red, PLA: green) of a cross section of a patterned graphene (GP) heterostructure used in the motion sensor of the present invention.
6 is a diagram showing the transmittance in the visible light region of the motion sensor (PLA (polylactic acid): black, PLA / SWNT (polylactic acid / single walled carbon nanotube): red) according to the present invention.
Figure 7 shows the sheet resistance of the initial (red), gold-doped (green), and silver nanowire-coated (blue) GP heterostructures. The inset of FIG. 7 is a SEM image of the GP coated with the silver nanowire.
Fig. 8 shows the human motion (left), its enlarged view (middle) with its corresponding bending radius, and the bending motion (right) at each bend radius.
Figure 9 shows the change in resistance per unit length of the initial (red), gold-doped (green), and silver nanowire-coated (blue) GP heterostructures, and the resistance varies inversely with the bending radius.
10 is a SEM photograph of the surface of the ITO film on the PET layer after bending the structure.
Figure 11 shows a finite element analysis showing the strain distribution of the GP heterostructure when the bending radius R is infinity (Figure 11a), 1.3 cm (Figure 11b), 0.52 cm (Figure 11c) and 0.38 cm (Figure 11d) (FEA) results and corresponding photographs of the bent heterostructure.
Figure 12 shows the output current (Figure 12a) and output voltage (Figure 12b) of a motion sensor made of PLA (blue) and SWNT-encapsulated PLA (red) as a function of time.
13A is an X-ray diffraction spectrum of a PLA / SWNT composite film, FIG. 13B is a Raman spectrum of a PLA / SWNT composite, and FIG. 13C is a description of each Raman peak.
14A and 14B show the piezoelectric output current and piezoelectric output voltage of a PLA / SWNT composite film which is half the SWNT concentration of the composite film of Fig. 12, Fig. 14C shows the cycle reliability test (150 or more bending operations 14D is a schematic view (right side) of a step of applying shear stress to the PLA / SWNT film and the piezoelectric output voltage (left side) of the PLA / SWNT composite film when the shear stress is distinct, 14f are photographs of a forward connection and a reverse connection setup for external data acquisition (external DAQ) for electrical characteristic measurement, respectively.
15A and 15B show the output voltage of the PLA / SWNT composite as a function of time in the forward and reverse connections, respectively.
Figure 16 shows charge separation in PLA / SWNT composite films under compressive and tensile stresses.
17A shows the stress distribution of the horizontal (left) and vertical (right) aligned SWNTs determined by FEA. 17B shows the output voltage (left side) and the corresponding output voltage of PLA / SWNT composite film over time as a function of the reciprocal of the bending radius, in the reciprocal of the other bending radius, Is a photograph showing the bending of the film of Fig. FIG. 17C shows the output voltage (left) and corresponding output voltage of the PLA / SWNT composite film over time at different pressures as a function of pressure (right), and the degree of insertion was measured in the vertical direction (red arrow) It is a photograph showing the film.
18 shows a schematic diagram of a punching process for the motion sensor of the present invention and an image (right side) of the motion sensor.
19 is a plot of the output voltage of the motion sensor as a function of time in four modes (unstrained, pressure-loaded, compressed and tensioned), and the inset of each graph is a photograph of the motion sensors of the four modes.
20 is a strain distribution corresponding to four modes (unconstrained, pressure-loaded, compression and tensile) obtained through FEA.

Hereinafter, the present invention will be described in more detail with reference to the following examples or drawings. It is to be understood, however, that the following description of the embodiments or drawings is intended to illustrate specific embodiments of the invention and is not intended to be exhaustive or to limit the scope of the invention to the precise forms disclosed.

Example  1. Silver Of nanowires (AgNW)  synthesis

5 ml of ethylene glycol (EG, JUNSEI, Japan) was poured into a 50 ml vial and heated in an oil bath (153 ° C) with stirring at 260 rpm to synthesize the nanowires. After heating for 30 minutes, 40 μL of 4 mM copper chloride (CuCl ₂ .2H ₂ O, 99%, DAEJUNG, Korea) solution dissolved in EG was added with heating for 15 minutes. 1.5 ml of 0.094 M silver nitrate (AgNO ₃ 99% +, Strem Chemicals, Inc.) dissolved in 1.5 mL of 0.147 M poly (vinylpyrrolidone) (PVP, avg. MW 55000, Aldrich, USA) and EG. , USA). After the injection, the reaction was allowed to proceed for 1 hour. Next, the silver nanowire solution was centrifuged and redispersed in acetone three times. Finally, the silver nanowires were dried and dispersed in ethanol to 1 wt%.

Example  2. Grapina  Synthetic and doping

Graphene was synthesized by chemical vapor deposition (CDV) on 25 μm copper foil (Alfa Aesar, USA). The copper foil was annealed at 1000 占 폚 for 1 hour with a constant hydrogen flow (8 sccm) and then methane gas (20 sccm) was inserted for 30 minutes. Subsequently, under a hydrogen atmosphere, the temperature of the chamber was rapidly cooled to room temperature. After the PMMA (A4, 495, Microchem, USA) was spin-coated, the graphene layer synthesized on the copper foil was immersed in a copper etching solution to etch copper, and the graphene / PMMA layer was floated. The separated graphene layer was washed with deionized water to remove the residual etchant. The backside of the graphene was doped by exposure to AuCl ₃ (Sigma-Aldrich, USA) solution (20 mM in DI) for 10 minutes.

Example  3. Transparent Wearable  Manufacture of motion / pressure sensor

A schematic manufacturing method is shown in Fig. PLA (Sigma Aldrich, USA) was dispersed in chloroform (98.5%, Samchun, Korea) at a concentration of 3 wt% using a magnetic stirrer. SWNT (Hanhwa, Korea) was also dispersed in chloroform under ultrasonic treatment (1.6 × 10 ^-6 wt%). The two dispersions were then drop cast into a slide glass to form a PLA / SWNT complex. After drying the dispersion for 24 hours at room temperature, the resulting PLA / SWNT composite film (about 70 μm thick) was separated from the slide glass. Next, PMMA was spin-coated on the synthesized graphene sheet, and the back side of the graphene sheet was exposed to the gold doping solution. The gold-doped graphene / PMMA film was transferred to a PLA / SWNT composite film. Finally, another gold doped graphene / PMMA film was transferred to the other side of the PLA / SWNT composite film.

Fig. 2 shows a transparent and stretchable piezoelectric motion sensor. A partially separated photograph of the motion sensor is shown in Fig. The device's ultra-thin, lightweight and stretch allows confomal intergration with the human skin and is considerably comfortable. Sprayed elastomeric films further improve adhesion (Yeo, W.-H., et al . Multifunctional epidermal pills are printed directly on the skin. Adv . Mater. 25 , 2773-2778 (2013)). Also, due to the high transparency, the device is still difficult to notice after partial delamination. The invisible, skin-conforming device using a transparent material has a natural, aesthetically pleasing appearance and assures privacy of the individual.

The structural design of the device and the properties of the materials used are shown in an enlarged view of the patterned graphene (GP) heterostructure used in the motion sensor (FIG. 4). The motion sensor (FIG. 5) is composed of a piezoelectric polymer thin film (PLA, approximately 70 μm) embedded in a piezoelectric graphene heterostructure, ie, SWNT, between the graphene electrodes and the insulating layers. The graphenes used are grown by chemical vapor deposition using copper as a catalyst and doped with a gold salt. A polymethacrylate (PMMA) layer insulates the device and improves the piezoelectric power-generation ability of the SWNT. 5 shows a scanning electron microscope (SEM) photograph of a section of a piezoelectric graphene heterostructure used in a motion sensor. The PMMA / graphene and PLA layers of the motion sensor are shown in red and green, respectively.

Example  4. Optical, electrical and mechanical properties

The transmittance of the motion sensor made of PLA and PLA / SWNT was measured in the visible light region (FIG. 6, 380 to 780 nm); The device exhibits high transparency. Indium tin oxide (ITO) electrodes are widely used as transparent electrodes. However, in the pristine state, graphene has sheet resistance higher than that of ITO, and therefore graphene must be deformed in order to improve the conductivity. Thus, conductive graphene heterostructures comprising silver nanowires, comprised of multi-layer graphene doped with gold chloride, are used. Figure 7 shows the sheet resistance measured for an initial state (696.5? /?), Gold doping (354.5? /?) And silver nanowire coating (98.8? /?) For a graphene electrode; The measured values indicate that the conductivity of graphene can be successfully increased by doping. The inset of FIG. 7 shows a SEM photograph of silver nanowire coated graphene.

One of the advantages of the graphene heterostructure for ITO is the extremely high mechanical deformability. The graphene heterostructure and the ITO film are bent at different bending radii using a bending step. The bending radius is measured based on the position of the bent human wrist (FIG. 8). In the bending test, it was confirmed that the graphene heterostructure was maintained at a high electrical conductivity even in an extremely bent state, whereas the ITO film showed a sharp increase in sheet resistance (FIG. 9). As shown in the SEM image of the ITO film (FIG. 10), the increase in resistance of the ITO is due to cracks formed when bent. On the other hand, cracks are not observed in the graphene heterostructure.

An analysis based on theoretical mechanics confirms this observation. Strain distributions for different bending radii of the graphene heterostructure and ITO films were obtained by FEA; A photograph of the experiment is shown in Figs. 11A to 11D. The red dotted box corresponds to the analysis area of FEA. The FEA results show that the local strain distributions of the graphene heterostructure and ITO film at the same bending radius are not much different. However, the ITO film (<~ 1%) (Peng , C., et al. In situ electro-mechanical experiments and mechanics modeling of tensile cracking in indium tin oxide thin films on polyimide substrates, J. Appl. Phys. 109, 103530 (2011)) and graphene heterostructures (> 5%) (Kim, KS , et al . Large-scale pattern growth of graphene films for stretchable transparent electrodes. Nature 457 , 706-710 (2009)) have different critical strains that cause mechanical cracking. The addition of nanowires thereby more improving the mechanical strength of the graphene hetero structures (Lee, M.-S., et al. High-Performance, Transparent, and Stretchable Electrodes Using GrapheneMetal Nanowire Hybrid Structures. Nano Lett. 13 , 28142821 (2013)). Thus, the conductive graphene heterostructure maintains its inherent electrical properties even during the dynamic operation of the human body.

Example  5. Piezoelectric GP Heterostructure

The steps involved in integrating the piezoelectric graphene heterostructure and the motion sensor are shown in FIG. Due to the low amplitude of the generated piezoelectric voltage and current, it is difficult to obtain a high SNR in the initial PLA layer (blue plot in FIGS. 12A and 12B). In order to amplify the generated piezoelectric signal, a SWNT is embedded in the PLA layer. The PLA / SWNT composite film exhibits a crystallinity of 39% as measured by X-ray diffraction analysis (FIG. 13A). The coexistence of PLA and SWNT in the PLA / SWNT complex was confirmed by Raman spectroscopy (FIGS. 13B and 13C). Under the same applied strain, the PLA / SWNT complex produced a current of about 4 nA and a voltage of about 210 mV (red plot in Figures 12a and 12b); These values are 8 times and 5 times higher (blue plot in FIGS. 12A and 12B) than in the case of PLA in the initial state. The increase in voltage and current is related to the concentration of SWNT in the complex. 14A and 14B show that the voltage and current generated by the PLA composite film, containing SWNTs that are half the original concentration, are between the voltages and currents corresponding to the blue and red plots in FIGS. 12A and 12B. Improvement of the piezoelectric properties of the composite is also found after a number of bending cycles (Fig. 14C). The piezoelectric voltage in the PLA / SWNT composite can also be generated by applying shear stress (FIG. 14D).

To verify that the measured signal is caused by piezoelectric charge generation, the polarity of the first peak voltage in a forward connection (Fig. 15c, Fig. 14e) is plotted in a reverse connection (Fig. 15d, Fig. 14f) . The difference in polarity between the two cases confirms that the signal is essentially piezoelectric. Further, even when the bending direction is changed, such a change in polarity is observed (Figs. 16 and 19). When the PLA / SWNT complex is subjected to compression or tensile strain, negative or positive charges accumulate adjacent to the upper and lower electrodes. This accumulation of charge is due to charge separation by strain in the PLA. On the other hand, the high Young's modulus of the SWNT improves the local strain resistance of the PLA and thus maximizes charge generation. This is evidenced by the fact that the strain is concentrated near the SWNT; It is also confirmed by FEA (applying 1% strain to the PLA / SWNT complex). Aligning the SWNT horizontally or vertically within the PLA; Two different cases are modeled (left and right photograph respectively in Fig. 17F). In both cases, the stress tends to be concentrated near the SWNTs (Park, K.-I., et al. Piezoelectric BaTiO ₃ thin film nano generator on plastic substrates. Nano Lett . 10 , 4939-4973 (2010)). In order to study the output voltage as a function of the applied strain, the voltage generated in the composite film was measured at various strains obtained by bending the film with different bending radii. Figure 17g shows a linear calibration curve (right) with a corresponding voltage output (left) and a slope of about 0.12 mV / cm &lt;& quot ^{; 1 &} gt ;. Figure 17h also shows the piezoelectric voltage output produced by applying different pressures in the composite film (left); The linear correlation curve showing the relationship between the two has a slope of about 0.8 mV / kPa (right). If the relationship between the piezoelectricity produced in the graphene heterostructure and the mechanical stimulus applied externally is linear, then the heterostructure is suitable for use as a sensing element in an iHMI.

Example  6. For motion detection Patterned  Piezoelectric GP Heterostructure

The PLA / SWNT composite film is patterned using a mechanical punching process (Fig. 18) to ensure a completely twisted and flexible design. The custom-made punching mask is placed on a press machine disposed on the piezoelectric graphene heterostructure film. The machine is then pressurized and depressurized to a suitable pressure. The fully serpentine configuration of the motion sensor enables reversible stretching (Fig. S6a). The sensor may also be disposed conformally to the human skin and thus remains in contact while the body is moving (Figure 19). The operation sensor generates a voltage during deformation such as pressing (right upper end), elongation (left lower end), or compression (right lower end) without generating a potential when it is not deformed (left upper end). The amplitude and polarity of the generated potential are dependent on the nature of the deformation (pressing versus elongation) and the direction of deformation (elongation versus compression). The generated potential is essentially piezoelectric; This is confirmed by the change in voltage polarity when different connections are used. The strain distribution in the motion sensor causing the output signal shown in Fig. 19 is predicted through FEA (Fig. 20); The FEA result describes the difference in amplitude and polarity of the potential. Using four different operation-induced signals, four command signals for controlling the machine can be generated.

Claims (19)

A first protective layer; A first electrode layer formed adjacent to the first passivation layer; A piezoelectric layer formed adjacent to the first electrode layer; A second electrode layer formed adjacent to the piezoelectric layer; And a second protective layer formed adjacent to the second electrode layer. The transparent and stretchable motion sensor according to claim 1, wherein the first protective layer is polymethyl methacrylate (PMMA) or polylactic acid (PLA). The transparent and stretchable motion sensor according to claim 1, wherein the thickness of the first protective layer is 50 nm to 100 占 퐉. The transparent and stretchable motion sensor of claim 1, wherein the first electrode layer is selected from the group consisting of graphene, single wall carbon nanotubes, and silver nanowires. The transparent, stretchable motion sensor of claim 4, wherein the graphene is graphene doped with gold. The transparent and stretchable motion sensor according to claim 1, wherein the thickness of the first electrode layer is 1 nm to 100 nm. The transparent and stretchable motion sensor according to claim 1, wherein the piezoelectric layer is a polylactic acid / single-walled carbon nanotube composite film. The transparent and stretchable motion sensor according to claim 7, wherein the size of the single-walled carbon nanotube is 50 nm to 1 mm. The transparent and stretchable motion sensor according to claim 1, wherein the piezoelectric layer has a thickness of 100 nm to 500 μm. The transparent and stretchable motion sensor according to claim 1, wherein the second electrode layer is selected from the group consisting of graphene, single wall carbon nanotubes and silver nanowires. 11. The transparent, stretchable motion sensor of claim 10, wherein the graphene is graphene doped with gold. The transparent and stretchable motion sensor according to claim 1, wherein the thickness of the second electrode layer is 1 nm to 100 nm. The transparent and stretchable motion sensor according to claim 1, wherein the second protective layer is polymethyl methacrylate (PMMA) or polylactic acid (PLA). The transparent and stretchable motion sensor according to claim 1, wherein the thickness of the second protective layer is 50 nm to 100 m. The transparent and stretchable motion sensor according to claim 1, wherein the first protective layer, the first electrode layer, the piezoelectric layer, the second electrode layer, and the second protective layer are patterned in a serpentine pattern. (i) drop casting a polylactic acid (PLA) dispersion and a single wall carbon nanotube (SWNT) dispersion to produce a PLA / SWNT composite film;
(ii) spin-coating polymethylmethacrylate (PMMA) on a graphene sheet to prepare a graphene / PMMA film; And
(ii) transferring the graphene / PMMA film onto both sides of the PLA / SWNT composite film. 17. The method of claim 16, wherein the thickness of the PLA / SWNT composite film is 100 nm to 500 m. 17. The method of claim 16, wherein the thickness of the graphene layer in the graphene / PMMA film is 1 nm to 100 nm. 17. The method of claim 16, wherein the thickness of the PMMA layer in the graphene / PMMA film is between 50 nm and 100 mu m.

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