BackgroundMany university students are lacking adequate physical exercise and are failing to develop physical activity (PA) behaviors in China. PA app use could improve this situation.ObjectiveThe aim of this study was to use the unified theory of acceptance and use of technology (UTAUT) to investigate the intention to use PA apps among university students in Guangzhou, China, and how body mass index (BMI) moderates the effects of UTAUT in explaining PA app use intention.MethodsA cross-sectional study was conducted among 1704 university students from different universities in Guangzhou, China. The UTAUT model was used to measure the determinants of intention to use PA apps.ResultsOf the participants, 41.8% (611/1461) intended to use PA apps. All three UTAUT-related scales (performance expectancy, effort expectancy, and social influence) were positively associated with the intention to use PA apps after adjusting for background variables (adjusted odds ratio 1.10-1.31, P<.001). The performance expectancy scale had stronger associations with the intention to use PA apps among those whose BMI were beyond normal range compared with those whose BMI were within normal range (P<.001).ConclusionsUTAUT is useful for understanding university students’ intention to use PA apps. Potential moderating effects should be kept in mind when designing UTAUT-based interventions to improve PA via app use.

Permanent magnets are essential components for many biomedical systems and electromechanical devices, which may be made into flexible formats to achieve wearable monitoring and effective integration with biological tissues. However, the development of high‐performance flexible permanent magnets is challenging due to their ultrathin geometries, which contradict with the thickness‐dependent magnetic properties. In addition, magnetic membranes with controllable sequences of polarities are difficult to achieve. Here, origami techniques to achieve flexible permanent magnetic membranes with enhanced magnetic field strength and programmable sequences of polarities are presented. Linear Halbach arrays, circular Halbach arrays, and concentric magnets with thicknesses ranging from 130 to 500 µm and bending curvatures ranging from 0.039 to 0.0043 µm−1 are achieved through different folding mechanisms. The origami membranes offer a maximum field intensity of 72 mT and extremely strong magnetic force of 0.21 N cm−2, allowing various novel applications demonstrated through electronics interfacing, cell manipulations, and soft robotics. The origami techniques offer large magnetism and complex spatial field distribution, and enable practical use of thin flexible magnetic membranes in constructing miniaturized or even flexible electromechanical systems and biomedical instruments for magnetic resonance imaging, targeted drug delivery, health monitoring, and cancer therapy.

Purpose To investigate the feasibility of real-time 3D magnetic resonance imaging (MRI) with simultaneous recording of physiological signals for identifying sites of airway obstruction during natural sleep in pediatric patients with sleep-disordered breathing. Methods Experiments were performed using a three-dimensional Fourier transformation (3DFT) gradient echo sequence with prospective undersampling based on golden-angle radial spokes, and L1-norm regularized iterative self-consistent parallel imaging (L1-SPIRiT) reconstruction. This technique was demonstrated in three healthy adult volunteers and five pediatric patients with sleep-disordered breathing. External airway occlusion was used to induce partial collapse of the upper airway on inspiration and test the effectiveness of the proposed imaging method. Apneic events were identified using information available from synchronized recording of mask pressure and respiratory effort. Results Acceptable image quality was obtained in seven of eight subjects. Temporary airway collapse induced via inspiratory loading was successfully imaged in all three volunteers, with average airway volume reductions of 63.3%, 52.5%, and 33.7%. Central apneic events and associated airway narrowing/closure were identified in two pediatric patients. During central apneic events, airway obstruction was observed in the retropalatal region in one pediatric patient. Conclusion Real-time 3D MRI of the pharyngeal airway with synchronized recording of physiological signals is feasible and may provide valuable information about the sites and nature of airway narrowing/collapse during natural sleep.

Coupling soft bodies and dynamic motions with multifunctional flexible electronics is challenging, but is essential in satisfying the urgent and soaring demands of fully soft and comprehensive robotic systems that can perform tasks in spite of rigorous spatial constraints. Here, the mobility and adaptability of liquid droplets with the functionality of flexible electronics, and techniques to use droplets as carriers for flexible devices are combined. The resulting active droplets (ADs) with volumes ranging from 150 to 600 µL can conduct programmable functions, such as sensing, actuation, and energy harvesting defined by the carried flexible devices and move under the excitation of gravitational force or magnetic force. They work in both dry and wet environments, and adapt to the surrounding environment through reversible shape shifting. These ADs can achieve controllable motions at a maximum velocity of 226 cm min−1 on a dry surface and 32 cm min−1 in a liquid environment. The conceptual system may eventually lead to individually addressable ADs that offer sophisticated functions for high‐throughput molecule analysis, drug assessment, chemical synthesis, and information collection.

Simultaneous neuron stimulation and biophysiological sensing in multi‐encephalic regions can lead to profound understanding of neural pathways, neurotransmitter transportation, and nutrient metabolism. Here, a flexible electronic device with tentacle‐like channels radiating from a central wireless circuit is presented. The device is constructed by different organic and inorganic materials that have been made into thin‐film or nanoparticle formats. All channels have been equipped with flexible components for distributed and synchronized opto‐electrical stimulation, biopotential sensing, and ion concentration monitoring. They can be implanted into different brain regions through adaptive bending and individually addressed to follow programmable working sequences. Experimental results conducted in vitro and in vivo have demonstrated the capability in generating optical or electrical stimulation, while sensing 16‐channels biopotential and concentration of Ca2+, Na+, and K+ ions in distributed regions. Behavior and immunohistochemistry studies suggest potential applications in regulating brain functions for freely moving animals. In combination with various functional materials, the device can serve as a comprehensive research platform that can be modularized to accommodate different needs for brain studies, offering numerous possibilities and combinations to yield sophisticated neuromodulation and behavior regulation.

With the proposed methods, both compliance and Pclose can be calculated and used to quantify airway collapsibility in OSA with an awake scan of 30 min total scan room time. J. Magn. Reson. Imaging 2016;44:158-167.

As an important means to protect water resources, water quality detection is of great social and economic significance. Water quality detection sensors processed by micro-electro-mechanical system (MEMS) technology have the advantages of low-cost, small size, and high sensitivity. In this paper, a multi-parameter water quality detection integrated sensor chip is further studied, and a portable detection system using this chip is developed. Temperature, pH, oxidation-reduction potential (ORP), conductivity and concentration of copper ions (Cu2+) are selected as typical water quality parameters. Experiments of sensor calibrations using this portable detection system were performed in standard solutions. The sensor has a sensitivity of −57.34 mV/pH in pH detection and 5.95 Ω/°C in temperature response. ORP is directly detected by Pt microelectrode on the chip and the relative error is less than 3%. The electrode constant of the sensor is 1.416 cm−1 and the linearity is 0.9995 in conductivity detection. With the gold nanoparticles deposited on the electrode, the detection peak of Cu2+ appears at 280 mV and the sensor shows good linearity to the concentration of Cu2+ in the range of 0–0.6 mg/L. The detection limit of Cu2+ concentration is 2.33 μg/L. Through measurement and calculation, the accuracy of the portable system is within 4%. This portable multi-parameter water quality detection system with the MEMS-based integrated chip shows great potential in the field and fast detection.

Optical fibers made of polymeric materials possess high flexibility that can potentially integrate with flexible electronic devices to realize complex functions in biology and neurology. Here, a multichannel flexible device based on four individually addressable optical fibers transfer‐printed with flexible electronic components and controlled by a wireless circuit is developed. The resulting device offers excellent mechanics that is compatible with soft and curvilinear tissues, and excellent diversity through switching different light sources. The combined configuration of optical fibers and flexible electronics allows optical stimulation in selective wavelengths guided by the optical fibers, while conducting distributed, high‐throughput biopotential sensing using the flexible microelectrode arrays. The device has been demonstrated in vivo with rats through optical stimulation and simultaneously monitoring of spontaneous/evoked spike signals and local field potentials using 32 microelectrodes in four brain regions. Biocompatibility of the device has been characterized by behavior and immunohistochemistry studies, demonstrating potential applications of the device in long‐term animal studies. The techniques to integrate flexible electronics with optical fibers may inspire the development of more flexible optoelectronic devices for sophisticated applications in biomedicine and biology.