Reversibly Stretchable Organohydrogel-Based Soft Electronics with Robust and Redox-Active Interfaces Enabled by Polyphenol-Incorporated Double Networks

Hydrogel electrolytes as soft ionic conductors have been extensively exploited to establish skinlike and biocompatible devices. However, in many common hydrogels, there exists irreversible elongation upon prolonged stretching cycles and poor interfacial contact, which have significantly hindered their practical applications where long-term operation at large deformations is needed. Herein, multifunctional soft electronic devices with reversible stretchability and improved electrode/electrolyte interfaces are demonstrated by employing polyacrylamide-based double-network organohydrogel electrolytes soaked with a high content of tannic acid (TA) that affords multiple noncovalent interactions and redox activity. Performances of the TA-rich gels are evaluated for the first time in realizing shape-recoverable stretchable devices against repeated deformations to 500% strain, with superior gel–electrode interfaces exhibiting both intimate adhesion and boosted electrochemical capacitance of >200 mF·cm–2. A maximal 4-fold higher capacitance can be achieved by introducing TA and ethylene glycol (EG) into hydrogels. Moreover, a soft electronic system consisting of stretchable supercapacitors and gel-based microsensors was demonstrated, in which the electronic performance of these devices can be well preserved after >1000 repeated cycles at strains of up to 200%, without obvious residual strain or electrode delamination. This could pave a route to the design of multifunctional gel networks tackling both the mechanical and interfacial issues in soft and biocompatible devices

Tip-Enhanced Sub-Femtomolar Steroid Immunosensing via Micropyramidal Flexible Conducting Polymer Electrodes for At-Home Monitoring of Salivary Sex Hormones

Noninvasive testing and continuous monitoring of ultralow-concentration hormones in biofluids have attracted increasing interest for health management and personalized medicine, in which saliva could fulfill the demand. Steroid sex hormones such as progesterone (P4) and β-estradiol (E2) are crucial for female wellness and reproduction; however, their concentrations in saliva can vary down to sub-pM and constantly fluctuate over several orders of magnitude. This remains a major obstacle toward user-friendly and reliable monitoring at home with low-cost flexible biosensors. Herein we introduce a 3D micropyramidal electrode architecture to address such challenges and achieve an ultrasensitive flexible electrochemical immunosensor with sub-fM-level detection capability of salivary sex hormones within a few minutes. This is enabled by micropyramidal electrode arrays consisting of a poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) thin film as the coating layer and electrochemically decorated gold nanoparticles (AuNPs) to improve the antibody immobilization. The enhanced mass transport around the 3D tips provided by the micropyramidal architecture is discovered to improve the detection limit by 3 orders of magnitude, pushing it to as low as ∼100 aM for P4 and ∼20 aM for E2, along with a wide linear range up to μM. Accordingly, these hormones down to sub-fM in >1000-fold-diluted saliva samples can be accurately measured by the printed soft immunosensors, thus allowing at-home testing through simple saliva dilution to minimize the interfering substances instead of centrifugation. Finally, monitoring of the female ovarian hormone cycle of both P4 and E2 is successfully demonstrated based on the centrifuge-free saliva testing during a period of 4 weeks. This ultrasensitive and soft 3D microarchitected electrode design is believed to provide a universal platform for a diverse variety of applications spanning from accurate clinical diagnostics and counselling and in vivo detection of bioactive species to environmental and food quality tracing

Ultrasoft and High-Adhesion Block Copolymers for Neuromorphic Computing

The “von Neumann bottleneck” is a formidable challenge in conventional computing, driving exploration into artificial synapses. Organic semiconductor materials show promise but are hindered by issues such as poor adhesion and a high elastic modulus. Here, we combine polyisoindigo-bithiophene (PIID-2T) with grafted poly­(dimethylsiloxane) (PDMS) to synthesize the triblock-conjugated polymer (PIID-2T-PDMS). The polymer exhibited substantial enhancements in adhesion (4.8–68.8 nN) and reductions in elastic modulus (1.6–0.58 GPa) while maintaining the electrical characteristics of PIID-2T. The three-terminal organic synaptic transistor (three-terminal p-type organic artificial synapse (TPOAS)), constructed using PIID-2T-PDMS, exhibits an unprecedented analog switching range of 276×, surpassing previous records, and a remarkable memory on–off ratio of 106. Moreover, the device displays outstanding operational stability, retaining 99.6% of its original current after 1600 write–read events in the air. Notably, TPOAS replicates key biological synaptic behaviors, including paired-pulse facilitation (PPF), short-term plasticity (STP), and long-term plasticity (LTP). Simulations using handwritten digital data sets reveal an impressive recognition accuracy of 91.7%. This study presents a polyisoindigo-bithiophene-based block copolymer that offers enhanced adhesion, reduced elastic modulus, and high-performance artificial synapses, paving the way for the next generation of neuromorphic computing systems

The primers used in this study.

<p>BSP, bisulfite sequencing PCR. CGI, CpG island.</p><p>The primers used in this study.</p

Massively Parallel Patterning of Complex 2D and 3D Functional Polymer Brushes by Polymer Pen Lithography

We report the first demonstration of centimeter-area serial patterning of complex 2D and 3D functional polymer brushes by high-throughput polymer pen lithography. Arbitrary 2D and 3D structures of poly­(glycidyl methacrylate) (PGMA) brushes are fabricated over areas as large as 2 cm × 1 cm, with a remarkable throughput being 3 orders of magnitudes higher than the state-of-the-arts. Patterned PGMA brushes are further employed as resist for fabricating Au micro/nanostructures and hard molds for the subsequent replica molding of soft stamps. On the other hand, these 2D and 3D PGMA brushes are also utilized as robust and versatile platforms for the immobilization of bioactive molecules to form 2D and 3D patterned DNA oligonucleotide and protein chips. Therefore, this low-cost, yet high-throughput “bench-top” serial fabrication method can be readily applied to a wide range of fields including micro/nanofabrication, optics and electronics, smart surfaces, and biorelated studies

The predicated TFBS of differentially methylated CpG sites within the b<i>Boule</i> promoter.

<p>Arrows indicate differentially methylated CpG sites. The TFBS is underlined.</p

<i>In vitro</i> methylation assay of the b<i>Boule</i> promoter.

<p>The b<i>Boule</i> core promoter construct pbBoule-107 was treated with M.SssI methylase, and then methylated (mpbBoule-107) or unmethylated (pbBoule-107) plasmids were transiently transfected into GC-1 and COS-7 cell lines. Normalized luciferase activities are expressed as mean ± SEM of at least three independent experiments. The bar above the histogram indicates the SEM. ^** indicate a significant difference (P < 0.01).</p

The methylation profile of the long CpG island in the b<i>Boule</i> 5' flanking region.

<p>(A) Schematic diagram of the long CGI within the b<i>Boule</i> promoter. (B) Schematic depiction of the CpG sites for methylation analysis. Nucleotide numbering is relative to +1 at the initiating ATG codon. The short vertical bars represent the CpG dinucleotides. (C) Methylation status of the b<i>Boule</i> promoter in the testes of cattle and cattle-yak hybrids. Each line represents an individual bacterial clone that was sequenced. Open circles indicate unmethylated CpG sites. Black circles indicate methylated CpG sites.</p

mRNA expression of b<i>Boule</i> in BMECs treated with 5-Aza-dC.

<p>mRNA expression was detected in treated cells but not in untreated cells by qRT-PCR. All experiments were performed three times. The bar above the histogram indicates the SEM. Different uppercase letters denote significant differences between different groups with a significance level of P < 0.01. Different lowercase letters denote significant differences between different groups with a significance level of P < 0.05.</p

3D-Printed Intrinsically Stretchable Organic Electrochemical Synaptic Transistor Array

Organic electrochemical transistors (OECTs) for skin-like bioelectronics require mechanical stretchability, softness, and cost-effective large-scale manufacturing. However, developing intrinsically stretchable OECTs using a simple and fast-response technique is challenging due to limitations in functional materials, substrate wettability, and integrated processing of multiple materials. In this regard, we propose a fabrication method devised by combining the preparation of a microstructured hydrophilic substrate, multi-material printing of functional inks with varying viscosities, and optimization of the device channel geometries. The resulting intrinsically stretchable OECT array with synaptic properties was successfully manufactured. These devices demonstrated high transconductance (22.5 mS), excellent mechanical softness (Young’s modulus ∼ 2.2 MPa), and stretchability (∼30%). Notably, the device also exhibited artificial synapse functionality, mimicking the biological synapse with features such as paired-pulse depression, short-term plasticity, and long-term plasticity. This study showcases a promising strategy for fabricating intrinsically stretchable OECTs and provides valuable insights for the development of brain-computer interfaces