猕猴对不同极化方向微波辐射能量吸收的研究

为提供微波辐射安全标准必要的数据，研究了不同极化方向微波辐射能量对猕猴的影响。实验在医学微波无反射室中进行，分为电场，磁场和微波传输方向极化组，辐射频率１ＧＨｚ，用红外热图技术，对暴露在三种极化方向电磁场中猕猴面部各解剖特片部位及胸部在辐射前后进行温度变化的定量分析。     

A method for exceptionally low noise single channel recordings

Summary We present a method whereby, with integrating electronics, quartz patch electrodes and a novel use of silicone oil, background noise levels as low as .083 pA RMS in a 5 kHz bandwidth (4-pole Butterworth filter) have been achieved in single channel patch clamp recordings. These approaches result in much higher signal to noise ratios for single channel recording than have previously been reported and should allow many investigators to significantly reduce noise at a constant bandwidth or to increase their recording bandwidths by several kHz.     

Fabrication of a Flexible Photodetector Based on a Liquid Eutectic Gallium Indium

A fluidic gallium-based liquid metal (LM) is an interesting material for producing flexible and stretchable electronics. A simple and reliable method developed to facilitate the fabrication of a photodetector based on an LM is presented. A large and thin conductive eutectic gallium indium (EGaIn) film can be fabricated with compressed EGaIn microdroplets. A solution of LM microdroplets can be synthesized by ultrasonication after mixing with EGaIn and ethanol and then dried on a PDMS substrate. In this study, a conductive LM film was obtained after pressing with another substrate. The film was sufficiently conductive and stretchable, and its electrical conductivity was 2.2 × 10⁶ S/m. The thin film was patterned by a fiber laser marker, and the minimum line width of the pattern was approximately 20 μm. Using a sticky PDMS film, a Ga₂O₃ photo-responsive layer was exfoliated from the fabricated LM film. With the patterned LM electrode and the transparent photo-responsive film, a flexible photodetector was fabricated, which yielded photo-response-current ratios of 30.3%, 14.7%, and 16.1% under 254 nm ultraviolet, 365 nm ultraviolet, and visible light, respectively.     

From the Cover: Wireless power transfer to deep-tissue microimplants

The ability to implant electronic systems in the human body has led to many medical advances. Progress in semiconductor technology paved the way for devices at the scale of a millimeter or less (“microimplants”), but the miniaturization of the power source remains challenging. Although wireless powering has been demonstrated, energy transfer beyond superficial depths in tissue has so far been limited by large coils (at least a centimeter in diameter) unsuitable for a microimplant. Here, we show that this limitation can be overcome by a method, termed midfield powering, to create a high-energy density region deep in tissue inside of which the power-harvesting structure can be made extremely small. Unlike conventional near-field (inductively coupled) coils, for which coupling is limited by exponential field decay, a patterned metal plate is used to induce spatially confined and adaptive energy transport through propagating modes in tissue. We use this method to power a microimplant (2 mm, 70 mg) capable of closed-chest wireless control of the heart that is orders of magnitude smaller than conventional pacemakers. With exposure levels below human safety thresholds, milliwatt levels of power can be transferred to a deep-tissue (>5 cm) microimplant for both complex electronic function and physiological stimulation. The approach developed here should enable new generations of implantable systems that can be integrated into the body at minimal cost and risk.Progress in semiconductor technology has led to electronic devices that can augment or replace physiological functions; their ability to be implanted for direct interaction with organ systems relies on overall miniaturization of the device for simplified delivery (e.g., via catheter or hypodermic needle) and access to interstitial spaces. Advances over the past few decades enable most components in a biomedical device, including electrodes, oscillators, memory, and wireless communication systems, to be integrated on tiny silicon chips. However, the energy required for electronic function remains substantial and the consumption density has not been matched by existing powering technologies (1). As a result, the vast bulk of most implantable electronic devices consists of energy storage or harvesting components.Although considerable progress has been made in energy storage technologies, batteries remain a major obstacle to miniaturization (2, 3) because their lifetimes are limited and highly constrained by the available volume, requiring periodic surgical replacement once the unit is depleted. Energy-harvesting strategies have been developed to eliminate batteries or to extend their function. Previous demonstrations include thermoelectric (4), piezoelectric (5–7), biopotential (8), or glucose (9, 10) power extraction. However, these methods are anatomically specific and, in their existing forms, yield power densities too low (<0.1 μW/mm²) for a microimplant.Alternatively, energy can be transferred from an external source. Ideally, power transfer should be completely noninvasive and not specific to regions in the body. Most existing approaches for this type of transfer are based on electromagnetic coupling in the near field (11–20). Though well-suited for large devices and prostheses (21, 22), near-field methods do not address key challenges to powering a microimplant: weak coupling between extremely asymmetric source and receiver structures (23), dissipative and heterogeneous tissue (24), and regulatory power thresholds for general safety (25). These challenges, compounded by the intrinsic exponential decay of the near field, severely limit miniaturization beyond superficial depths (>1 cm), even if the battery can be removed.Theory has indicated that these problems can be overcome in the electromagnetic midfield (23): energy transfer in this region, defined to be about a wavelength’s distance from the source, occurs through the coupling between evanescent fields in air and propagating modes in tissue. Using a patterned metal plate to control the near field, we demonstrate milliwatt levels of power transfer to a miniaturized coil deep in heterogeneous tissue (>5 cm), with exposure levels below safety thresholds for humans; this enables us to power a microimplant capable of delivering controlled electrical pulses to nearly anywhere in the body. The device consists of a multiturn coil structure, rectifying circuits for AC/DC power conversion, a silicon-on-insulator integrated circuit (IC) for pulse control, and electrodes, entirely assembled within a 2-mm diameter, 3.5-mm height device small enough to fit inside a catheter. We demonstrate wireless function by operating it in human-scale heart and brain environments, and by wirelessly regulating cardiac rhythm through a chest wall.     

Adaptive optoelectronic camouflage systems with designs inspired by cephalopod skins

Octopus, squid, cuttlefish, and other cephalopods exhibit exceptional capabilities for visually adapting to or differentiating from the coloration and texture of their surroundings, for the purpose of concealment, communication, predation, and reproduction. Long-standing interest in and emerging understanding of the underlying ultrastructure, physiological control, and photonic interactions has recently led to efforts in the construction of artificial systems that have key attributes found in the skins of these organisms. Despite several promising options in active materials for mimicking biological color tuning, existing routes to integrated systems do not include critical capabilities in distributed sensing and actuation. Research described here represents progress in this direction, demonstrated through the construction, experimental study, and computational modeling of materials, device elements, and integration schemes for cephalopod-inspired flexible sheets that can autonomously sense and adapt to the coloration of their surroundings. These systems combine high-performance, multiplexed arrays of actuators and photodetectors in laminated, multilayer configurations on flexible substrates, with overlaid arrangements of pixelated, color-changing elements. The concepts provide realistic routes to thin sheets that can be conformally wrapped onto solid objects to modulate their visual appearance, with potential relevance to consumer, industrial, and military applications.Recently established understanding of many of the key organ and cellular level mechanisms of cephalopod metachrosis (1–5) creates opportunities for the development of engineered systems that adopt similar principles. Here, critical capabilities in distributed sensing and actuation (6–9) must be coupled with elements that provide tunable coloration, such as the thermochromic systems reported here or alternatives such as cholesteric liquid crystals (10–13), electrokinetic and electrofluidic structures (14, 15), or colloidal crystals (16–19). Although interactive displays that incorporate distributed sensors for advanced touch interfaces (20–22) might have some relevance, such capabilities have not been explored in flexible systems or in designs that enable adaptive camouflage. The results reported here show that advances in heterogeneous integration and high-performance flexible/stretchable electronics provide a solution to these critical subsystems when exploited in thin multilayer, multifunctional assemblies. The findings encompass a complete set of materials, components, and integration schemes that enable adaptive optoelectronic camouflage sheets with designs that capture key features and functional capabilities of the skins of cephalopods. These systems combine semiconductor actuators, switching components, and light sensors with inorganic reflectors and organic color-changing materials in a way that allows autonomous matching to background coloration, through the well-known, separate working principles of each component. The multilayer configuration and the lamination processes used for assembly, along with the photopatternable thermochromic materials, are key to realization of these systems. Demonstration devices capable of producing black-and-white patterns that spontaneously match those of the surroundings, without user input or external measurement, involve multilayer architectures and ultrathin sheets of monocrystalline silicon in arrays of components for controlled, local Joule heating, photodetection, and two levels of matrix addressing, combined with metallic diffuse reflectors and simple thermochromic materials, all on soft, flexible substrates. Systematic experimental, computational, and analytical studies of the optical, electrical, thermal, and mechanical properties reveal the fundamental aspects of operation, and also provide quantitative design guidelines that are applicable to future embodiments.The skin of a cephalopod enables rapid, patterned physiological color change, or metachrosis, in a thin three-layered system (2, 23–25). The topmost layer is pigmentary coloration: chromatophore organs that retract or expand rapidly by direct control of muscles that are in turn controlled by nerves originating in the brain. This physiological on/off speed change ranges from ca. 250 to 750 ms. The middle and bottom layers are composed of structural coloration components. The middle layer comprises iridophore cells that can reflect all colors depending on angle of view; some are passive cells and others are physiologically controlled by a slower system: They can be turned on/off in 2–20 s (depending on species, or different cell types on different parts of the body). The bottom layer comprises leucophores (i.e., “white cells”) that are entirely passive (i.e., no physiological control; they are always “on”). This layer diffuses white in all directions (25) and can act as a bright backdrop against which expanded pigmentary chromatophores are viewed; this provides one way in which contrast of the pattern can be controlled (i.e., darkly pigmented chromatophores next to bright white reflective elements).The central control of skin patterning resides in the eyes, which, together with the central and peripheral nervous system, sense the visual background and route control signals throughout the skin to produce a coordinated pattern for communication or camouflage. In addition, the skin contains molecules known as opsins, which are known to be photosensitive in the retina and are thought to be photosensitive in the skin as well. They are hypothesized to play a role in distributed light sensing and control in the periphery (26), thus potentially adding a noncentralized component for skin patterning that enables sensing and actuation independent of the brain.One of the most important features of cephalopod skin—one that provides maximum optical diversity of appearances—is the coordinated action of (i) chromatophores, (ii) iridophores, (iii) leucophores, (iv) muscles, (v) central ocular organs, and (vi) distributed opsins (2, 23–25). The work described here demonstrates pixelated devices that include analogs to each of these key elements, except for the second and fifth, which can be easily incorporated with known photonic materials and conventional digital imagers.     

实例引入法在医用电子学教学中的应用

目的：探索实例引入法在医用电子学教学中的有效性。方法分别选取西安医学院2013级和2014级医学影像学专业各60名学生作为对照组和实验组,对2013级学生采用传统教学,对2014级学生采用实例引入法教学。通过比较两组综合成绩、学生问卷调查结果和后续专业课教师评分,评价基于实例引入法的教学效果。结果实验组学生的综合成绩中,不及格率、优良率、平均分分别为5.0%、30%、74分,均优于对照组的16.7%、13.3%和69.58分,差异均具有统计学意义(P<0.05);在学生自我评价及教师评价中,各对比指标也均优于对照组,差异均具有统计学意义(P<0.05)。结论基于实例引入法可以使医用电子学中的抽象理论形象化,帮助学生更好的理解和掌握医用电子学的相关知识。     

A Flexible Two-Sensor System for Temperature and Bending Angle Monitoring

A wearable electronic system constructed with multiple sensors with different functions to obtain multidimensional information is essential for making accurate assessments of a person’s condition, which is especially beneficial for applications in the areas of health monitoring, clinical diagnosis, and therapy. In this work, using polyimide films as substrates and Pt as the constituent material of serpentine structures, flexible temperature and angle sensors were designed that can be attached to the surface of an object or the human body for monitoring purposes. In these sensors, changes in temperature and bending angle are converted into variations in resistance through thermal resistance and strain effects with a sensitivity of 0.00204/°C for temperatures in the range of 25 to 100 °C and a sensitivity of 0.00015/° for bending angles in the range of 0° to 150°. With an appropriate layout design, two sensors were integrated to measure temperature and bending angles simultaneously in order to obtain decoupled, compensated, and more accurate information of temperature and angle. Finally, the system was tested by being attached to the surface of a knee joint, demonstrating its application potential in disease diagnosis, such as in arthritis assessment.     

A Stretchable,Self-Healable Triboelectric Nanogenerator as Electronic Skin for Energy Harvesting and Tactile Sensing

Electronic skin that is deformable, self-healable, and self-powered has high competitiveness for next-generation energy/sense/robotic applications. Herein, we fabricated a stretchable, self-healable triboelectric nanogenerator (SH-TENG) as electronic skin for energy harvesting and tactile sensing. The elongation of SH-TENG can achieve 800% (uniaxial strain) and the SH-TENG can self-heal within 2.5 min. The SH-TENG is based on the single-electrode mode, which is constructed from ion hydrogels with an area of 2 cm × 3 cm, the output of short-circuit transferred charge (Qsc), open-circuit voltage (Voc), and short-circuit current (Isc) reaches ~6 nC, ~22 V, and ~400 nA, and the corresponding output power density is ~2.9 μW × cm⁻² when the matching resistance was ~140 MΩ. As a biomechanical energy harvesting device, the SH-TENG also can drive red light-emitting diodes (LEDs) bulbs. Meanwhile, SH-TENG has shown good sensitivity to low-frequency human touch and can be used as an artificial electronic skin for touch/pressure sensing. This work provides a suitable candidate for the material selection of the hydrogel-based self-powered electronic skin.     

Synthesis of Stretchable,Environmentally Stable,Conducting Polymer PEDOT Using a Modified Acid Template Random Copolymer

Although poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) has good electrical conductivity and high transparency in most applications, its usage in stretchable applications is limited because of its rigidity, reduced conductivity after elongation, and poor environmental stability. This study addresses these issues by incorporating the soft and relatively hydrophobic moiety poly(ethylene glycol) methacrylate (PEGMA). By incorporating PEGMA randomly in the rigid PSS chain, a soft and hydrophobic copolymer P(SS‐co‐PEGMA) is obtained. The conducting P(SS‐co‐PEGMA)‐based polymer‐coated PET film exhibits good resistance even after 400% elongation. In addition, PEDOT:P(SS‐co‐PEGMA) has better environmental stability than PEDOT:PSS because of the presence of the relatively hydrophobic PEGMA moiety in the chain. Moreover, the potential applicability of the synthesized flexible and stretchable electronic material as a stretchable matrix is established, which includes inorganic conductors (AgNW). When this material is stretched, it can be applied as a conductive interconnector to maintain the electrical pathway, instead of the other insulating matrices.     

Clinical Efficacy of Electronic Apex Locators: Systematic Review

Introduction

Apical constriction has been proposed as the most appropriate apical limit for the endodontic working length. Despite being the most used, some limitations are attributed to the radiographic method of working length determination. It lacks precision because it is based on the average position of the apical constriction. The electronic apex locators have been presented as an alternative to the odontometry performed by radiography. These devices detect the transition of the pulp to the periodontal tissue, which is anatomically very close to the apical constriction and may perform with improved accuracy.

Methods

A systematic review was performed to compare the radiographic and electronic methods. Clinical studies that compared both methods were searched for on 7 electronic databases, a manual search was performed on the bibliography of articles collected on the electronic databases, and the authors were contacted to ask for references of more research not detected on the electronic and manual search.

Results

Twenty-one articles were selected. The majority were comparative or evaluation studies, and very few clinical studies comparing both methods are available. Several methodological limitations are present on the collected articles and debated in this review.

Conclusions

Although the available scientific evidence base is short and at considerable risk of bias, it is still possible to conclude that the apical locator reduces the patient radiation exposure and also that the electronic method may perform better on the working length determination. At least one radiographic control should be performed to detect possible errors of the electronic devices.