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Rubbery transistor under mechanical strain. (A and B) Representative transfer curves of the intrinsically stretchable transistors under mechanical strains of 0, 10, 30, 50, and 0% (released) along (A) and perpendicular (B) to the channel length direction. (C) Changes of the mobility during stretching to 50% strain along and perpendicular to the channel length direction. (D) Changes of the mobility after stretch-release cycles at 30% strain along and perpendicular to the channel length direction. (E) Photograph of the transistor array. (F) Mobility distribution in the transistor array. Photo credit: Ying-Shi Guan, University of Houston.
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A rubber-like stretchable semiconductor with high carrier mobility is the most important yet challenging material for constructing rubbery electronics and circuits with mechanical softness and stretchability at both microscopic (material) and macroscopic (structural) levels for many emerging applications. However, the development of such a rubbery...
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... onto a target substrate can be implemented in a scalable roll-to-roll manner, as shown in Fig. 1D. The nanofilm was transferred onto a 5-cm-wide polyethylene terephthalate film through rolling at the speed of 5 mm s −1 . Figure 1E shows the optical microscope image of a nanofilm on a Si wafer. The nanofilm is measured to be 60 nm thick ( fig. S3) and is continuous and uniform across the whole wafer. X-ray diffraction (XRD) spectroscopy was used to gain insight into the molecular packing within the nanofilm. As shown in Fig. 1F, the assembled pristine P3HT nanofilm (in red) exhibits three distinct multiorder [(h00), h = 1,2,3] diffraction peaks at 5.2°, 10.5°, and 15.7°, while ...
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... rubbery transistors retain their functions even under 50% applied mechanical strain. Figure 3 (A and B) shows the transfer curves of the rubbery transistor under 0, 10, 30, 50, and 0% (released) uniaxial strain along and perpendicular to the channel length direction, respectively. When the transistor was stretched perpendicular to the channel length direction, the on current of the transistor shows a monotonic decrease from 1.81 mA at 0% to 1.67 mA at 10%, to 1.10 mA at 30%, and to 0.90 mA at 50% strain. ...
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... ratio decreased from 1.83 × 10 5 at 0% to 1.72 × 10 5 at 10%, to 1.09 × 10 5 at 30%, to 0.48 × 10 5 at 50% strain, and to 0.85 × 10 5 at 0% strain, upon releasing the stretching. The threshold voltage remained at ~2.55 V when stretched at different levels. The calculated mobilities under different levels of mechanical strain are presented in Fig. 3C. The average mobility experienced a slight decrease (5.8%) from 8.6 cm 2 V −1 s −1 to 8.1 cm 2 V −1 s −1 when the device was stretched by 30% strain along the channel length direction, and a moderate decrease (20.9%) to 6.8 cm 2 V −1 s −1 when stretched by 50%. After the mechanical stretching was released, the average mobility P3HT wt ...
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... at 50% strain. The average mobility was recovered to 8.0 cm 2 V −1 s −1 when the stretching was fully released. These results show that the rubbery transistor can function well under large mechanical strain. In addition, to evaluate its reliability under cyclic deformation, the transistor was repeatedly stretched and released for 500 times by 30% (Fig. 3D). The average mobility slightly decreased to 8.0 cm 2 V −1 s −1 and to 7.0 cm 2 V −1 s −1 after 500 cycles of stretching and releasing along and perpendicular to the channel length direction, respectively. Figure S12 shows the cyclic stretching and releasing test at 30% strain for 500 cycles. Table S1 shows the comparison of our fully ...
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... test at 30% strain for 500 cycles. Table S1 shows the comparison of our fully stretchable transistors with reported fully rubbery stretchable transistors. We further constructed an array of rubbery transistors to illustrate the device uniformity, which is critical for integrated electronics. The photograph of a 6 × 6 transistor array is shown in Fig. 3E. The schematic illustration of the array is shown in fig. S13A, and the detailed fabrication processes are described in Materials and Methods. The transistors in the array have a high yield of 100%, as can be seen from the array's mobility map shown in Fig. 3F. As also illustrated in fig. S13B, the highest and average mobilities are ...
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... for integrated electronics. The photograph of a 6 × 6 transistor array is shown in Fig. 3E. The schematic illustration of the array is shown in fig. S13A, and the detailed fabrication processes are described in Materials and Methods. The transistors in the array have a high yield of 100%, as can be seen from the array's mobility map shown in Fig. 3F. As also illustrated in fig. S13B, the highest and average mobilities are 8.85 and 8.57 cm 2 V −1 s −1 , respectively. The array also shows a fairly uniform on/off current ratio with an average value of 3.25 × 10 5 ( fig. S14). In addition, the hysteresis loop of the rubbery transistor is shown in fig. S15, which shows a slight and ...
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... Such nanocomposites also need to be mechanically soft, thin and biocompatible, allowing them to be seamlessly interfaced with tissues and organs 7,8 . Typical design strategies to achieve stretchable electronics rely on engineering electronic fillers (for example, nanoparticles, nanowires and nanosheets) on or inside intrinsically elastic polymers that have insulating or relatively low conductive properties [9][10][11] . Such conductive fillers with percolation networks can provide carrier transport channels at large deformability. ...
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... Interfacial self-assembly is a competitive candidate for developing conformal liquid metal film. Widely adopted in various fields, this technique enables the fabrication of monolayers composed of diverse nanomaterials, including metallic nanoparticles and nanowires 22,23 , carbon-based nanomaterials 24 , and organic nanomaterials 25 . In contrast to conventional methods for producing conformal devices, such as substrate sacrificial transferring, the interfacial self-assembled film is more amiable to complex surfaces [26][27][28][29] . ...
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... 128 Similarly, most polymers with π-conjugated structures are used as conductors or semiconductors. Among the various polymers, poly(3,4-ethylene dioxythiophene) poly(styrene sulfonate) (PEDOT:PSS), 75,[129][130][131][132] polyaniline (PANI), 133 poly(3-hexylthiophene) (P3HT), 134 and polypyrrole (PPY) 135 are the most widely used because of their high electrical performance, ease to processing, and excellent biocompatibility. ...
... Reproduced with permission. 134 Copyright 2020, The American Association for the Advancement of Science. polymer chains, mainly caused by hydrogen bonds and electrostatic interactions at the air-water interface. ...
... Rubber electronic materials are competitive in terms of both high carrier mobility and scalability. Yu et al. 134 demonstrated an interfacial assembly method for fabricating rubbery stretchable semiconducting nanofilms at air/water interfaces to improve the uniformity of integrated electronic devices. Stratification quickly emerged within 2 min once the compound solution of P3HT dissolved in toluene was dropped into water. ...
Intelligent technologies based on artificial intelligence and big data hold great potential for health monitoring and human–machine capability enhancement. However, electronics must be connected to the human body to realize this vision. Thus, tissue or skin‐like electronics with high stretchability and low stiffness mechanical properties are highly desirable. Ultrathin materials have attracted significant attention from the research community and the industry because of their high performance and flexibility. Over the past few years, considerable progress has been made in flexible ultrathin sensors and devices based on ultrathin materials. Here, we review the developments in this area and examine representative research progress in ultrathin materials fabrication and device construction. Strategies for the fabrication of stretchable ultrathin materials and devices are considered. The relationship between the thin‐film structure and performance is emphasized and highlighted. Finally, the current capabilities and limitations of ultrathin devices were explored.
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... Conjugated polymer semiconductors have been widely used as semiconductor materials for OFETs due to their advantages, such as solution processability [19], flexibility [20,21], and large-area processing. The mobility of organic semiconducting materials has increased significantly [22][23][24][25][26][27], enabling the switching of electronic circuits in stretchable devices. However, high-mobility conjugated polymers have poor stretchability, which limits their application in stretchable devices. ...
... Although leading to significant improvements in the stretchability of semiconductors, molecular design engineering involves complex chemical synthesis steps, hindering large-scale applications. Physical blending is a simple and effective method for preparing high-performance stretchable organic semiconductors, including the blending of conjugated polymers with elastomers [23,[39][40][41][42][43] or molecular additives [44]. In blended systems, phase separation has an important effect on stretchability and electrical properties. ...
Stretchable organic field-effect transistors (OFETs) are fundamental components of organic integrated circuits and wearable biosensors. Stretchable organic semiconductors are core materials to realize high-mobility stretchable OFETs. Achieving polymer semiconductors with both high mobility and high stretchability is an urgent challenge. In this work, high-mobility stretchable semiconducting blend films were prepared by blending a polymer semiconductor with an elastomer. The polymer forms unique nanofibers through the nanoconfinement effect. The as-prepared blend films have low crystallinity and high aggregation degree, resulting in high stretchability and high mobility. Remarkably, the fully stretchable organic transistors exhibit hole maximum mobilities of 2.74 and 2.53 cm2 V−1 s−1 at 0% and 100% strain, respectively. Even at 150% strain, stretchable transistors have a maximum mobility of 1.57 cm2 V−1 s−1. The stretchable transistors show high mechanical robustness during 1000 stretching-releasing cycles at 30% strain.
... To impart that the membrane has the mechanical stretching ability, a SEBS elastomer was added to the P3HT-toluene polymer solution. 31 Then, the polymer solution was gently dropped on the surface of deionized water, and due to the Marangoni effect, the polymer solution spread fast over the water's surface. 32,33 Figure 1B shows the assembly process of the P3HT film, which is formed in approximately 2 min. ...
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... To seamlessly integrate and hybridize with soft tissues, the materials must possess mechanical stretchability at the microscopic material level and the macroscopic structural level [4][5][6] . Among different elastic electronic materials, stretchable semiconductors are particularly important in determining the electrical performances of stretchable transistors and circuits [7][8][9] . Although efforts have been made to develop elastic semiconductors, the scalable fabrication of elastic rubber-like semiconductors with high carrier mobility and large mechanical stretchability remains a key challenge 10 . ...
... The electrical performances of the LPSM-1-thin-film-based transistor array is summarized in Supplementary Table 1. The hysteresis loop curve of the rubbery transistor is shown in Supplementary Fig. 15, which exhibits a comparable hysteresis for ion-gel-based transistors 9,10 . ...
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... To overcome this problem and further improve the performance of the device, the research group has innovatively reported a method for scalable assembling a freestanding binaryphased composite nanofilm based on the air/water interface. 210 As shown in the Figure 19D, as toluene and water are immiscible solvent, the author first dissolved P3HT in toluene and drop it on the water surface. Using the flatness of the interface and the volatilization of the solvent, the hydrophobic molecules would gradually selfassemble into nano-films in an orderly manner, which packing structure is similar to that existing in the crystalline P3HT nanofibers. ...
... Furthermore, in order to better compare the comprehensive performance of tactile sensors with different sensing mechanisms (Resistive, Capacitive, Piezoelectric, and Triboelectric), we summarize the outstanding works in the field in Table 3 [210] piezoresistive, capacitive, and piezoelectric sensors, on the one hand, the FET tactile sensor has an excellent signal amplification effect, which can detect the signal in situ and amplify the output, so it has extremely high sensitivity. On the other hand, the mature microfabrication processing technology of FET makes it easier to realize the micro and nanointegration of FET-based tactile sensors, thus achieving higher resolution. ...
... 56 To achieve human-like dexterity in robotic arms or prosthetics, tactile sensors attached to their surface need to obtain the following characteristics in addition to the high sensitivity and wide detection range of common pressure sensors: in-situ detection, 71 high-resolution, 189 stretchable, 72 self-healing, 203 and biocompatible. 210 Fortunately, as the building-block elements in circuits for signal processing and calculation, FET possess typical three-terminal structure and unique working principles, which enables its different components to detect external mechanics through different sensing mechanisms, which can be used as a very sensitive piezoresistive or capacitance detection platform. 110,158 Besides, FET can be used as a signal amplifier for weak signal capture in situ, in ascending tactile sensor sensitivity at the same time realize the on-site application of devices. ...
The past several decades have witnessed great progress in high‐performance field effect transistors (FET) as one of the most important electronic components. At the same time, due to their intrinsic advantages, such as multiparameter accessibility, excellent electric signal amplification function, and ease of large‐scale manufacturing, FET as tactile sensors for flexible wearable devices, artificial intelligence, Internet of Things, and other fields to perceive external stimuli has also attracted great attention and become a significant field of general concern. More importantly, FET has a unique three‐terminal structure, which enables its different components to detect external mechanics through different sensing mechanisms. On one hand, it provides an important platform to shed deep insights into the underlying mechanisms of the tactile sensors. On the other hand, these properties could in turn endow excellent components for the construction of tactile matrix sensor arrays with high quality. With special emphasis on the configuration of FETs, this review classified and summarized structure‐optimized FET tactile sensors with gate, dielectric layer, semiconductor layer, and source/drain electrodes as sensing active components, respectively. The working principles and the state‐of‐the‐art protocols in terms of high‐performance tactile sensors are detail discussed and highlighted, the innovative pixel distribution and integration analysis of the transistor sensor matrix array concerning flexible electronics are also introduced. We hope that the introduction of this review can provide some inspiration for future researchers to design and fabricate high‐performance FET‐based tactile sensor chips for flexible electronics and other fields.
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... Chemical compositions, mechanical properties, and response to biomaterials affect biocompatibility. Usually, biocompatible materials are bioinert (stainless steel, titanium alloy, silicone rubber, hydroxyapatite ceramics, etc. [344]). Biodegradable materials are disintegrated in physiological aqueous solutions at a controlled rate after a specified time. ...
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... Transistors are essential building-blocks for such stretchable electronics, as they process various input signals and control the operations of other components 4 . There are two main strategies to make these crucial transistors and circuits stretchable: using intrinsically stretchable materials, including conductors, dielectrics, and semiconductors [5][6][7][8][9][10][11] , or placing non-stretchable devices on rigid islands and connecting these islands with stretchable interconnects, which can be made of serpentine shaped bridges, liquid metals, etc. [12][13][14][15][16][17][18][19][20] . For this, functional islands are almost completely decoupled with strain and stretchable wirings take up almost the entire deformation. ...
Transistors with inorganic semiconductors have superior performance and reliability compared to organic transistors. However, they are unfavorable for building stretchable electronic products due to their brittle nature. Because of this drawback, they have mostly been placed on non-stretchable parts to avoid mechanical strain, burdening the deformable interconnects, which link these rigid parts, with the strain of the entire system. Integration density must therefore be sacrificed when stretchability is the first priority because the portion of stretchable wirings should be raised. In this study, we show high density integration of oxide thin film transistors having excellent performance and reliability by directly embedding the devices into stretchable serpentine strings to defeat such trade-off. The embedded transistors do not hide from deformation and endure strain up to 100% by themselves; thus, integration density can be enhanced without sacrificing the stretchability. We expect that our approach can create more compact stretchable electronics with high-end functionality than before.
