Skin sensors are of paramount importance for flexible wearable electronics, which are active in medical diagnosis and healthcare monitoring. Ultrahigh sensitivity, large measuring range, and high skin conformability are highly desirable for skin sensors. Here, an ultrathin flexible piezoresistive sensor with high sensitivity and wide detection range is reported based on hierarchical nanonetwork structured pressuresensitive material and nanonetwork electrodes. The hierarchical nanonetwork material is composed of silver nanowires (Ag NWs), graphene (GR), and polyamide nanofibers (PANFs). Among them, Ag NWs are evenly interspersed in a PANFs network, forming conductive pathways. Also, GR acts as bridges of crossed Ag NWs. The hierarchical nanonetwork structure and GR bridges of the pressure-sensitive material enable the ultrahigh sensitivity for the pressure sensor. More specifically, the sensitivity of 134 kPa −1 (0−1.5 kPa) and the low detection of 3.7 Pa are achieved for the pressure sensor. Besides, the nanofibers act as a backbone, which provides effective protection for Ag NWs and GR as pressure is applied. Hence, the pressure sensor possesses an excellent durability (>8000 cycles) and wide detection range (>75 kPa). Additionally, ultrathin property (7 μm) and nanonetwork structure provide high skin conformability for the pressure sensor. These superior performances lay a foundation for the application of pressure sensors in physiological signal monitoring and pressure spatial distribution detection.

A novel energy-efficient V CM-based monotonic capacitor switching scheme for successive approximation register (SAR) analogue to-digital converters (ADCs) is proposed. Based on the third reference voltage V CM and monotonic capacitor switching procedure, the proposed switching scheme achieves 97.66% less switching energy and 75% less number of capacitors over the conventional architecture, resulting in the most energy-efficient switching scheme among the reported switching sequences.

The realization of liquid metal-based wearable systems will be a milestone toward high-performance, integrated electronic skin. However, despite the revolutionary progress achieved in many other components of electronic skin, liquid metal-based flexible sensors still suffer from poor sensitivity due to the insufficient resistance change of liquid metal to deformation. Herein, a nacreinspired architecture composed of a biphasic pattern (liquid metal with Cr/Cu underlayer) as "bricks" and strain-sensitive Ag film as "mortar" is developed, which breaks the long-standing sensitivity bottleneck of liquid metal-based electronic skin. With 2 orders of magnitude of sensitivity amplification while maintaining wide (>85%) working range, for the first time, liquid metal-based strain sensors rival the state-of-art counterparts. This liquid metal composite features spatially regulated cracking behavior. On the one hand, hard Cr cells locally modulate the strain distribution, which avoids premature cut-through cracks and prolongs the defect propagation in the adjacent Ag film. On the other hand, the separated liquid metal cells prevent unfavorable continuous liquid-metal paths and create crack-free regions during strain. Demonstrated in diverse scenarios, the proposed design concept may spark more applications of ultrasensitive liquid metal-based electronic skins, and reveals a pathway for sensor development via crack engineering.

Most advanced humidity sensors are powered by batteries that need regular charging and replacement, causing environmental problems and complicated management issues. This paradigm has been overcome through the development of new technology based on the concept of simple, self-powered, rapid-response, flexible humidity sensors enabled by the properties of densely packed titanium dioxide (TiO 2 ) nanowire networks. These sensors eliminate the need for an external power source and produce an output voltage that can be readily related to ambient humidity level over a wide range of ambient conditions. They are characterized by rapid response and relaxation times (typically 4.5 and 2.8 s, respectively). These units are mechanically flexible and maintain a constant voltage output after 10 000 bending cycles. This new type of humidity sensor is easily attached to a human finger for use in the monitoring of ambient humidity level in the environment around human skin, near wet objects, or in the presence of moist materials. The unique properties of this new self-powered wearable humidity sensor technology open up a variety of new applications, including the development of electronic skin, personal healthcare products, and smart tracking in the future Internet-of-things.

The analysis of exhaled breath is an increasingly important role in the provision of security and in the management of personal healthcare. The development of self‐powered, reliable, miniature low cost and noninvasive devices is fundamental to practical applications. However, most state‐of‐the‐art self‐powered systems are incorporating mechanical nanogenerators, which would promote contact failures of electronics and limit minimization of the monitoring system. This work outlines a new solution to this problem based on a self‐powered breath analyzer integrated with a hydroelectric nanogenerator (HENG), in which the nanogenerator extracts electrical power from biochemical energy. The output signal from the sensor in this device is highly sensitive to the concentration of ethanol exhaled in breath down to low detection limitation of 50 ppm. A high dynamic range is observed whereby a signal response of ≈80% relative to peak value is obtained under the exposure to gas containing 100 ppm of ethanol. Unlike conventional self‐powered breathing analyzers based on piezoelectric or triboelectric nanogenerators, mechanical vibrations are eliminated. The availability of this compact breath analyzer provides a new detection regime for gas sensing, and should facilitate the design of a wide range of self‐powered systems incorporated in the next generation of innovative electronic devices.

No abstract

<h4>BACKGROUND AND OBJECTIVE</h4> <p> To measure the concentrations of transforming growth factor-beta1 and beta2 (TGF-beta1 and TGF-beta2) in the aqueous humor of patients with neovascular glaucoma (NVG). </p> <h4>PATIENTS AND METHODS</h4> <p> Patients were divided into four groups: NVG secondary to central retinal vein occlusion (group 1), NVG secondary to proliferative diabetic retinopathy (group 2), central retinal vein occlusion without rubeosis (group 3), and senile cataract (group 4). The total TGF-beta1 and TGF-beta2 concentrations in the aqueous humor of the four groups were measured by enzyme linked immunosorbent assay. </p> <h4>RESULTS</h4> <p> The mean concentrations of total TGF-beta1 were 600.7 &plusmn; 436.7 &micro;g/mL in group 1, 802.0 &plusmn; 359.5 &micro;g/mL in group 2, and undetectable in groups 3 and group 4 (<em>P </em>&lt; .05). The mean concentrations of total TGF-beta2 were 6,307.9 &plusmn; 2,206.2 &micro;g/mL in group 1, 5,908.0 &plusmn; 2,033.2 &micro;g/mL in group 2, 899.7 &plusmn; 425.6 &micro;g/mL in group 3, and 385.7 &plusmn; 189.9 &micro;g/mL in group 4. The total TGF-beta1 and TGF-beta2 concentrations in groups 1 and 2 were significantly higher than those in groups 3 and 4, whereas the total TGF-beta2 concentration in group 3 was significantly higher than that in group 4 (<em>P</em> &lt; .05). There was no significant difference in the TGF-beta1 or TGF-beta2 concentrations between groups 1 and 2 (<em>P</em> &gt; .05). </p> <h4>CONCLUSIONS</h4> <p>The abnormally high concentrations of TGF-beta1 and TGF-beta2 in the aqueous humor of patients with NVG may explain some aspects of the pathogenesis of NVG and the high failure rate of filtering operations in NVG. </p> <p>[<cite>Ophthalmic Surg Lasers Imaging</cite> 2007;38:6-14.] </p> <h4>AUTHORS</h4> <p>From the Department of Ophthalmology (X-BY, X-HS, W-YG, S-HQ, F-RM, Y-LS), Shanghai Eye and ENT Hospital, Fudan University, Shanghai, People&rsquo;s Republic of China; the Department of Ophthalmology (ED), University of the Witwatersrand, Johannesburg, South Africa; and The Royal Victorian Eye &amp; Ear Hospital (GJBS), East Melbourne, Victoria, Australia. </p> <p>Accepted for publication June 14, 2006. </p> <p>Supported by research grants (No. Z23) from Shanghai Eye and ENT Hospital, Fudan University, Shanghai, People&rsquo;s Republic of China. </p> <p>Address correspondence to Xing-Huai Sun, MD, PhD, Department of Ophthalmology, Shanghai Eye and ENT Hospital, Fudan University, 83 Fenyang Road, Shanghai, 20031, People&rsquo;s Republic of China. </p>

Besides the rapid progress of flexible components such as flexible sensors, [3,4] stretchable electrodes, [5,6] soft actuators, [7,8] flexible power sources, [9] further advancements of electronic skins require delicate integrations of subcomponents into highly operative flexible system, which arouses considerable attention in recent years. [10][11][12] For the scalable production of such integrated electronic skins, highly stretchable and cost-effective conductors serving as flexible electrodes/ circuits are indispensable. Due to rich resources, good physical properties, and well-developed processing techniques, metals have been a backbone material to promote human societies from the Bronze Age to the industrial revolutions. However, the application of metal conductors is largely hindered in flexible electronics due to insufficient stretchability, which can hardly survive in various flexible/ stretchable operation scenarios. In recent years, researchers sought to tailor the electromechanical performance of thin films via elegantly regulating the film-cracking process. [13][14][15] In representative work, Gong et al. reported a programmable cracking strategy, which remarkably improved the strain sensitivity of elastic conductors by locally adjusting cracking morphologies. [14] Similarly, several crack engineering strategies were proposed to improve the stretchability of metal films, such as interlayer insertion, [16] two-stage cracking, [17] film wrinkling, [18] and substrate structuring. [19] Nevertheless, to date, a facile preparation of metal-film conductors with ultrahigh stretchability (>150% strain range) remains a grand challenge (Figure 1b).Nature reserves abundant elegant biostructures as sources for innovations of flexible electronics, as exemplified by spiderinspired ultrasensitive sensors, [20] leaflet-mimicking tactile sensors, [21] and biogradients-inspired programmable flexible sensing. [22] Leaf venation, which is the arrangement of veins in the mesophyll matrix of leaves, exhibits rich patterns to adapt to the surrounding environment. [23] It is found that venation patterns significantly regulate the mechanical performance of leaves, [24,25] which hints at the potential to alter the electromechanical performance of metal films via venation-mimicking crack patterns.Future electronic skin systems require stretchable conductors and lowtemperature integration of external components, which remains challenging for traditional metal films. Herein, a bioinspired design concept is reported to endow metal films with 200% stretchability as well as room-temperature integration capability with diverse components. It is revealed that by controllable implantation of defects, distinctive venation-mimicking cracking modes can be induced in strained metal films, leading to profound stretchability regulation. An intriguing exponential-to-linear transition of the film electromechanical performance is observed, which is elucidated by a unified model covering the essence of all modes. Combined with room-temperature in...