Stretchable organic optoelectronic sensorimotor synapse

Emulation of human sensory and motor functions becomes a core technology in bioinspired electronics for next-generation electronic prosthetics and neurologically inspired robotics. An electronic synapse functionalized with an artificial sensory receptor and an artificial motor unit can be a fundamental element of bioinspired soft electronics. Here, we report an organic optoelectronic sensorimotor synapse that uses an organic optoelectronic synapse and a neuromuscular system based on a stretchable organic nanowire synaptic transistor (s-ONWST). The voltage pulses of a self-powered photodetector triggered by optical signals drive the s-ONWST, and resultant informative synaptic outputs are used not only for optical wireless communication of human-machine interfaces but also for light-interactive actuation of an artificial muscle actuator in the same way that a biological muscle fiber contracts. Our organic optoelectronic sensorimotor synapse suggests a promising strategy toward developing bioinspired soft electronics, neurologically inspired robotics, and electronic prostheses.

Effects of Molecular Structure and Packing Order on the Stretchability of Semicrystalline Conjugated Poly(Tetrathienoacene-diketopyrrolopyrrole) Polymers

The design of polymer semiconductors possessing high charge transport performance, coupled with good ductility, remains a challenge. Understanding the distribution and behavior of both crystalline domains and amorphous regions in conjugated polymer films, upon an applied stress, shall provide general guiding principles to design stretchable organic semiconductors. Structure–property relationships (especially in both side chain and backbone engineering) are investigated for a series of poly(tetrathienoacene-diketopyrrolopyrrole) polymers. It is observed that the fused thiophene diketopyrrolopyrrole-based polymer, when incorporated with branched side chains and an additional thiophene spacer in the backbone, exhibits improved mechanical endurance and, in addition, does not show crack propagation until 40% strain. Furthermore, this polymer exhibits a hole mobility of 0.1 cm2 V−1 s−1 even at 100% strain or after recovered from strain, which reveals prominent continuity and viscoelasticity of the polymer thin film. It is also observed that the molecular packing orientations (either edge-on or face-on) significantly affect the mechanical compliance of the polymer films. The improved stretchability of the polymers is attributed to both the presence of soft amorphous regions and the intrinsic packing arrangement of its crystalline domains

Characterization of Hydrogen Bonding Formation and Breaking in Semiconducting Polymers under Mechanical Strain

status: publishe

Quadruple H-bonding cross-linked supramolecular polymeric materials as substrates for stretchable, antitearing, and self-healable thin film electrodes

Herein, we report a de novo chemical design of supramolecular polymer materials (SPMs-1–3) by condensation polymerization, consisting of (i) soft polymeric chains (polytetramethylene glycol and tetraethylene glycol) and (ii) strong and reversible quadruple H-bonding cross-linkers (from 0 to 30 mol %). The former contributes to the formation of the soft domain of the SPMs, and the latter furnishes the SPMs with desirable mechanical properties, thereby producing soft, stretchable, yet tough elastomers. The resulting SPM-2 was observed to be highly stretchable (up to 17 000% strain), tough (fracture energy ∼30 000 J/m2), and self-healing, which are highly desirable properties and are superior to previously reported elastomers and tough hydrogels. Furthermore, a gold, thin film electrode deposited on this SPM substrate retains its conductivity and combines high stretchability (∼400%), fracture/notch insensitivity, self-healing, and good interfacial adhesion with the gold film. Again, these properties are all highly complementary to commonly used polydimethylsiloxane-based thin film metal electrodes. Last, we proceed to demonstrate the practical utility of our fabricated electrode via both in vivo and in vitro measurements of electromyography signals. This fundamental understanding obtained from the investigation of these SPMs will facilitate the progress of intelligent soft materials and flexible electronics.NRF (Natl Research Foundation, S’pore)MOE (Min. of Education, S’pore)Accepted versio

A Rapid and Facile Soft Contact Lamination Method: Evaluation of Polymer Semiconductors for Stretchable Transistors

Organic stretchable electronics have attracted extensive scientific and industrial interest because they can be stretched, twisted, or compressed, enabling the next-generation of organic electronics for human/machine interfaces. These electronic devices have already been described for applications such as field-effect transistors, photovoltaics, light-emitting diodes, and sensors. High-performance stretchable electronics, however, currently still involve complicated processing steps to integrate the substrates, semiconductors, and electrodes for effective performance. Herein, we describe a facile method to efficiently identify suitable semiconducting polymers for organic stretchable transistors using soft contact lamination. In our method, the various polymers investigated are first transferred on an elastomeric poly­(dimethylsiloxane) (PDMS) slab and subsequently stretched (up to 100%) along with the PDMS. The polymer/PDMS matrix is then laminated on source/drain electrode-deposited Si substrates equipped with a PDMS dielectric layer. Using this device configuration, the polymer semiconductors can be repeatedly interrogated with laminate/delaminate cycles under different amounts of tensile strain. From our obtained electrical characteristics, e.g., mobility, drain current, and on/off ratio, the strain limitation of semiconductors can be derived. With a facile soft contact lamination testing approach, we can thus rapidly identify potential candidates of semiconducting polymers for stretchable electronics

Deformable organic nanowire field-effect transistors

Deformable electronic devices that are impervious to mechanical influence when mounted on surfaces of dynamically changing soft matters have great potential for next-generation implantable bioelectronic devices. Here, deformable field-effect transistors (FETs) composed of single organic nanowires (NWs) as the semiconductor are presented. The NWs are composed of fused thiophene diketopyrrolopyrrole based polymer semiconductor and high-molecular-weight polyethylene oxide as both the molecular binder and deformability enhancer. The obtained transistors show high field-effect mobility >8 cm(2) V-1 s(-1) with poly(vinylidenefluoride-co-trifluoroethylene) polymer dielectric and can easily be deformed by applied strains (both 100% tensile and compressive strains). The electrical reliability and mechanical durability of the NWs can be significantly enhanced by forming serpentine-like structures of the NWs. Remarkably, the fully deformable NW FETs withstand 3D volume changes (>1700% and reverting back to original state) of a rubber balloon with constant current output, on the surface of which it is attached. The deformable transistors can robustly operate without noticeable degradation on a mechanically dynamic soft matter surface, e.g., a pulsating balloon (pulse rate: 40 min(-1) (0.67 Hz) and 40% volume expansion) that mimics a beating heart, which underscores its potential for future biomedical applications.

Quadruple H‑Bonding Cross-Linked Supramolecular Polymeric Materials as Substrates for Stretchable, Antitearing, and Self-Healable Thin Film Electrodes

Herein, we report a de novo chemical design of supramolecular polymer materials (SPMs-<b>1</b>–<b>3</b>) by condensation polymerization, consisting of (i) soft polymeric chains (polytetramethylene glycol and tetraethylene glycol) and (ii) strong and reversible quadruple H-bonding cross-linkers (from 0 to 30 mol %). The former contributes to the formation of the soft domain of the SPMs, and the latter furnishes the SPMs with desirable mechanical properties, thereby producing soft, stretchable, yet tough elastomers. The resulting SPM-<b>2</b> was observed to be highly stretchable (up to 17 000% strain), tough (fracture energy ∼30 000 J/m²), and self-healing, which are highly desirable properties and are superior to previously reported elastomers and tough hydrogels. Furthermore, a gold, thin film electrode deposited on this SPM substrate retains its conductivity and combines high stretchability (∼400%), fracture/notch insensitivity, self-healing, and good interfacial adhesion with the gold film. Again, these properties are all highly complementary to commonly used polydimethylsiloxane-based thin film metal electrodes. Last, we proceed to demonstrate the practical utility of our fabricated electrode via both in vivo and in vitro measurements of electromyography signals. This fundamental understanding obtained from the investigation of these SPMs will facilitate the progress of intelligent soft materials and flexible electronics

Quadruple H‑Bonding Cross-Linked Supramolecular Polymeric Materials as Substrates for Stretchable, Antitearing, and Self-Healable Thin Film Electrodes

Herein, we report a de novo chemical design of supramolecular polymer materials (SPMs-<b>1</b>–<b>3</b>) by condensation polymerization, consisting of (i) soft polymeric chains (polytetramethylene glycol and tetraethylene glycol) and (ii) strong and reversible quadruple H-bonding cross-linkers (from 0 to 30 mol %). The former contributes to the formation of the soft domain of the SPMs, and the latter furnishes the SPMs with desirable mechanical properties, thereby producing soft, stretchable, yet tough elastomers. The resulting SPM-<b>2</b> was observed to be highly stretchable (up to 17 000% strain), tough (fracture energy ∼30 000 J/m²), and self-healing, which are highly desirable properties and are superior to previously reported elastomers and tough hydrogels. Furthermore, a gold, thin film electrode deposited on this SPM substrate retains its conductivity and combines high stretchability (∼400%), fracture/notch insensitivity, self-healing, and good interfacial adhesion with the gold film. Again, these properties are all highly complementary to commonly used polydimethylsiloxane-based thin film metal electrodes. Last, we proceed to demonstrate the practical utility of our fabricated electrode via both in vivo and in vitro measurements of electromyography signals. This fundamental understanding obtained from the investigation of these SPMs will facilitate the progress of intelligent soft materials and flexible electronics

Quadruple H‑Bonding Cross-Linked Supramolecular Polymeric Materials as Substrates for Stretchable, Antitearing, and Self-Healable Thin Film Electrodes

Herein, we report a de novo chemical design of supramolecular polymer materials (SPMs-<b>1</b>–<b>3</b>) by condensation polymerization, consisting of (i) soft polymeric chains (polytetramethylene glycol and tetraethylene glycol) and (ii) strong and reversible quadruple H-bonding cross-linkers (from 0 to 30 mol %). The former contributes to the formation of the soft domain of the SPMs, and the latter furnishes the SPMs with desirable mechanical properties, thereby producing soft, stretchable, yet tough elastomers. The resulting SPM-<b>2</b> was observed to be highly stretchable (up to 17 000% strain), tough (fracture energy ∼30 000 J/m²), and self-healing, which are highly desirable properties and are superior to previously reported elastomers and tough hydrogels. Furthermore, a gold, thin film electrode deposited on this SPM substrate retains its conductivity and combines high stretchability (∼400%), fracture/notch insensitivity, self-healing, and good interfacial adhesion with the gold film. Again, these properties are all highly complementary to commonly used polydimethylsiloxane-based thin film metal electrodes. Last, we proceed to demonstrate the practical utility of our fabricated electrode via both in vivo and in vitro measurements of electromyography signals. This fundamental understanding obtained from the investigation of these SPMs will facilitate the progress of intelligent soft materials and flexible electronics