Robust, self-adhesive, reinforced polymeric nanofilms enabling gas-permeable dry electrodes for long-term application.

Robust polymeric nanofilms can be used to construct gas-permeable soft electronics that can directly adhere to soft biological tissue for continuous, long-term biosignal monitoring. However, it is challenging to fabricate gas-permeable dry electrodes that can self-adhere to the human skin and retain their functionality for long-term (>1 d) health monitoring. We have succeeded in developing an extraordinarily robust, self-adhesive, gas-permeable nanofilm with a thickness of only 95 nm. It exhibits an extremely high skin adhesion energy per unit area of 159 µJ/cm2 The nanofilm can self-adhere to the human skin by van der Waals forces alone, for 1 wk, without any adhesive materials or tapes. The nanofilm is ultradurable, and it can support liquids that are 79,000 times heavier than its own weight with a tensile stress of 7.82 MPa. The advantageous features of its thinness, self-adhesiveness, and robustness enable a gas-permeable dry electrode comprising of a nanofilm and an Au layer, resulting in a continuous monitoring of electrocardiogram signals with a high signal-to-noise ratio (34 dB) for 1 wk.

Ultraflexible organic light-emitting diodes for optogenetic nerve stimulation.

Organic electronic devices implemented on flexible thin films are attracting increased attention for biomedical applications because they possess extraordinary conformity to curved surfaces. A neuronal device equipped with an organic light-emitting diode (OLED), used in combination with animals that are genetically engineered to include a light-gated ion channel, would enable cell type-specific stimulation to neurons as well as conformal contact to brain tissue and peripheral soft tissue. This potential application of the OLEDs requires strong luminescence, well over the neuronal excitation threshold in addition to flexibility. Compatibility with neuroimaging techniques such as MRI provides a method to investigate the evoked activities in the whole brain. Here, we developed an ultrathin, flexible, MRI-compatible OLED device and demonstrated the activation of channelrhodopsin-2-expressing neurons in animals. Optical stimulation from the OLED attached to nerve fibers induced contractions in the innervated muscles. Mechanical damage to the tissues was significantly reduced because of the flexibility. Owing to the MRI compatibility, neuronal activities induced by direct optical stimulation of the brain were visualized using MRI. The OLED provides an optical interface for modulating the activity of soft neuronal tissues.

Fabrication and Unique Optical Properties of Two-Dimensional Silver Nanorod Arrays with Nanometer Gaps on a Silicon Substrate from a Self-Assembled Template of Diblock Copolymer.

A periodic array of nanoholes was fabricated via the self-assembly of a polystyrene(PS)-b-poly(methyl methacrylate) (PMMA) block copolymer (BCP) on a silicon substrate and selective etching of the PMMA moieties. Silver nanorods (AgNRs) were then selectively deposited in the nanoholes by a galvanic displacement reaction where the pattern was hexagonally aligned according to the template. The diameter of AgNRs was controlled by changing the immersion time. Optical measurements of the AgNR arrays revealed that the extinction peak was split into two because of the electromagnetically induced transparency effect. In addition, the AgNR arrays showed a surface-enhanced Raman scattering response and were successfully transferred from a silicon substrate to a transparent and flexible polymer film while retaining the rod arrangement.

Sensitivity to refractive index of high-aspect-ratio nanofins with optical vortex.

An easy and large-scale fabrication technique of metal fins was used to produce periodic Au fin arrays that realized light confinement in the near-infrared region. Light confinement was revealed by vortex patterns in the optical power flow of an array of high-aspect-ratio fins (height of 1000 nm for a width of 50 nm). The light confinement resulted in sharp dips in the reflectance spectrum of the high-aspect-ratio fin array. The wavelengths of the reflectance dips were found to shift toward higher values when the refractive index of the surrounding medium was increased. Experimental and simulated dip shift values were in good agreement with a demonstrated sensitivity of 580 nm per refractive index unit.

General anesthesia with remimazolam for a pediatric patient with MELAS and recurrent epilepsy: a case report.

BACKGROUND: Mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) is a mitochondrial disease. We report here the safe use of remimazolam in a pediatric MELAS patient. CASE PRESENTATION: A 10-year-old girl (118 cm, 16 kg) was scheduled for an open gastrostomy to improve nutrition and epileptic seizure control. We induced and maintained general anesthesia with remimazolam, remifentanil, fentanyl, and rocuronium. We also performed a bilateral subcostal transversus abdominis plane block before the surgery. The surgery finished uneventfully. After we discontinued remimazolam administration, the patient woke up immediately but calmly without flumazenil. Epileptic seizures did not occur during intra- and early post-operative periods. CONCLUSION: Remimazolam enabled us to provide a pediatric MELAS patient with general anesthesia without causing delayed emergence or epileptic seizures.

Self-powered ultraflexible photonic skin for continuous bio-signal detection via air-operation-stable polymer light-emitting diodes.

Ultraflexible optical devices have been used extensively in next-generation wearable electronics owing to their excellent conformability to human skins. Long-term health monitoring also requires the integration of ultraflexible optical devices with an energy-harvesting power source; to make devices self-powered. However, system-level integration of ultraflexible optical sensors with power sources is challenging because of insufficient air operational stability of ultraflexible polymer light-emitting diodes. Here we develop an ultraflexible self-powered organic optical system for photoplethysmogram monitoring by combining air-operation-stable polymer light-emitting diodes, organic solar cells, and organic photodetectors. Adopting an inverted structure and a doped polyethylenimine ethoxylated layer, ultraflexible polymer light-emitting diodes retain 70% of the initial luminance even after 11.3 h of operation under air. Also, integrated optical sensors exhibit a high linearity with the light intensity exponent of 0.98 by polymer light-emitting diode. Such self-powered, ultraflexible photoplethysmogram sensors perform monitoring of blood pulse signals as 77 beats per minute.

A durable nanomesh on-skin strain gauge for natural skin motion monitoring with minimum mechanical constraints.

Ultraconformable strain gauge can be applied directly to human skin for continuous motion activity monitoring, which has seen widespread application in interactive robotics, human motion detection, personal health monitoring, and therapeutics. However, the development of an on-skin strain gauge that can detect human body motions over a long period of time without disturbing the natural skin movements remains a challenge. Here, we present an ultrathin and durable nanomesh strain gauge for continuous motion activity monitoring that minimizes mechanical constraints on natural skin motions. The device is made from reinforced polyurethane-polydimethylsiloxane (PU-PDMS) nanomeshes and exhibits excellent sustainability, linearity, and durability with low hysteresis. Its thinness geometry and softness provide minimum mechanical interference on natural skin deformations. During speech, the nanomesh-attached face exhibits skin strain mapping comparable to that of a face without nanomeshes. We demonstrate long-term facial stain mapping during speech and the capability for real-time stable full-range body movement detection.

Dual-gate organic phototransistor with high-gain and linear photoresponse.

The conversion of light into electrical signal in a photodetector is a crucial process for a wide range of technological applications. Here we report a new device concept of dual-gate phototransistor that combines the operation of photodiodes and phototransistors to simultaneously enable high-gain and linear photoresponse without requiring external circuitry. In an oppositely biased, dual-gate transistor based on a solution-processed organic heterojunction layer, we find that the presence of both n- and p-type channels enables both photogenerated electrons and holes to efficiently separate and transport in the same semiconducting layer. This operation enables effective control of trap carrier density that leads to linear photoresponse with high photoconductive gain and a significant reduction of electrical noise. As we demonstrate using a large-area, 8 × 8 imaging array of dual-gate phototransistors, this device concept is promising for high-performance and scalable photodetectors with tunable dynamic range.

Ultraflexible organic photonic skin.

Thin-film electronics intimately laminated onto the skin imperceptibly equip the human body with electronic components for health-monitoring and information technologies. When electronic devices are worn, the mechanical flexibility and/or stretchability of thin-film devices helps to minimize the stress and discomfort associated with wear because of their conformability and softness. For industrial applications, it is important to fabricate wearable devices using processing methods that maximize throughput and minimize cost. We demonstrate ultraflexible and conformable three-color, highly efficient polymer light-emitting diodes (PLEDs) and organic photodetectors (OPDs) to realize optoelectronic skins (oe-skins) that introduce multiple electronic functionalities such as sensing and displays on the surface of human skin. The total thickness of the devices, including the substrate and encapsulation layer, is only 3 µm, which is one order of magnitude thinner than the epidermal layer of human skin. By integrating green and red PLEDs with OPDs, we fabricate an ultraflexible reflective pulse oximeter. The device unobtrusively measures the oxygen concentration of blood when laminated on a finger. On-skin seven-segment digital displays and color indicators can visualize data directly on the body.