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The development of a multimodal sensing platform with multiple layers for electronic skin (e-skin) sensing of temperature and pressure has attracted considerable interest to practical applications in soft robotics, human-machine interfaces, and wearable health monitoring. In this work, we demonstrated a new platform technology with multiple sandwiched layers of highly oriented carbon nanotube membrane and polyacrylonitrile for the integration of pressure and temperature sensory functionalities into a single platform that is thin, ultra-lightweight, flexible, and wearable. The key technology of in situ deposition of sensor platform on objects or in robot interface makes this a unique method for the development of e-skins for robotic applications, offering a new approach to wearable electronics and portable health care.

We report for the first time a lightweight, flexible and wearable hot-film flow sensor for real-time monitoring of human respiration. The sensor was manufactured by spinning and electrospinning methods from spinnable carbon nanotube (CNT) forest grown on silicon wafers and polyacrylonitrile (PAN). The sensor exhibited high sensitivity of 340 mV/(m/s), excellent flexibility, wearability and stability under bending and other mechanical disturbances. We successfully demonstrated a CNT wearable patch affixed to human upper lip for real-time monitoring of human respiration. The results indicate that our sensor can be employed to monitor sleep quality, personal health care and other clinical evaluations.

Pressure sensing is a critical task of microelectromechanical systems with a wide range of applications. Enhancing the performance such as sensitivity, durability, reliability, linearity and response time of pressure sensors has always been a top priority for researchers and technology developers. This paper demonstrates a new method for enhancing the performance of a piezoresistive pressure sensor. By using light illumination combined with controlling supply current, the performance of a 3C-SiC/Si heterojunction piezoresistive pressure sensor is significantly improved. The sensitivity of the pressure sensor is enhanced a few hundred thousand times under bright condition in comparison with that under dark condition. This enhancement is unprecedented for a micromachined pressure sensor. In addition, the durability, signal to noise ratio and measurement range are substantially improved.

Here we report for the first time an ultra-sensitive opto-piezoresistive effect in cubic silicon carbide (3C-SiC) nanofilms grown on silicon (Si). The sensitivity of the sensor was significantly enhanced by coupling the photovoltaic effect and controlling distribution of hole/electron in semiconductors. By applying this method, the gauge factor (GF) of strain sensors can be improved at least three orders of magnitude compared to conventional MEMS sensor. A GF of approximately 58,000 was observed, which is the highest GF reported for semiconductor piezoresistive sensors to date. Consequently, our findings can be deployed to develop ultra-sensitive mechanical sensors and MEMS/NEMS sensing applications.

This work presents the fabrication, mechanical strength characterization, and cell culture demonstration of a high aspect ratio silicon carbide (SiC) membrane. Optimizations in the deposition and fabrication make an ultra-high aspect ratio up to 20,000 SiC membranes with high fracture strength possible. Utilizing the superior properties of SiC material, the ultra-thin SiC membrane is a promising for cell culture/stretching devices, enabling very short optical accesses. The biocompatibility of the SiC membrane was confirmed with the 3T3 fibroblasts cell viability rate of 92.7%, in which the cells flattened and elongated their morphology while maintaining a strong adhesion to the SiC surface.

This work presents a conversion free p-type 4H silicon carbide (4H-SiC) four-terminal strain sensor utilizing a large Hall offset voltage in a symmetric four-terminal configuration. Upon the application of mechanical strain, a high sensitivity of 209 mV/A/ppm was obtained. The strain sensor also exhibited good repeatability and linearity with a significantly large offset voltage in the induced strain ranging from 0 to 334ppm. Coupled these performances with the excellent mechanical strength, electrical conductivity, thermal stability, and chemical inertness of the SiC material, the proposed 4H-SiC strain sensor is promising for stress/strain monitoring for harsh operating environments with high signal-to-noise ratio.

Developing flexible pressure sensors is of high interest in soft skin and tactile sensing applications. Here we demonstrate a simple approach to fabricating a sensitive resistive pressure sensor using carbon nanotube (CNT) micro-yarns as a pressure sensing element which is constructed on a stretchable acrylic elastomer. The sensor showed a high sensitivity of −0.86 Ω/kPa and a fast response time of 100 ms. Different to the longitudinal piezoresistive effect of micro-yarns, the high pressure sensitivity of the sensor was achieved owing to the compressibility of the micro-yarn in the direction perpendicular to the yarn axis. The sensor was also able to monitor finger pressure in real-time, demonstrating its potential for tactile sensing applications.

In this paper, we propose an extended navigation framework for autonomous mobile robots in dynamic environments using a reinforcement learning algorithm. The main idea of the proposed algorithm is to provide the mobile robots the relative position and motion of the surrounding objects to the robots, and the safety constraints such as minimum distance from the robots to the obstacles, and a learning model. We then distribute the mobile robots into a dynamic environment. The mobile robots will automatically learn to adapt to the environment by their own experienced through the trial-and-error interaction with the surrounding environment. When the learning phase is completed, the mobile robots equipped with our proposed framework are able to navigate autonomously and safely in the dynamic environment. The simulation results in a simulated environment shows that, our proposed navigation framework is capable of driving the mobile robots to avoid dynamic obstacles and catch up dynamic targets, providing the safety for the surrounding objects and the mobile robots.

This paper presents an active disturbance rejection rejection control design for integrated guidance and control missile based on sliding mode control and extended state observer. The integrated model is formulated as a block-strict-feedback nonlinear system, in which modeling errors, unmodeled non-linearities, target maneuvers, etc. are viewed as unknown uncertainties. The nonlinear control law is designed based on backstepping and sliding mode control (SMC) techniques. Based on the principle of active disturbance rejection control (ADRC), enhanced feedback linearization (FL) based control law is implemented for the IGC model using the estimates generated by an extended state observer (ESO). The stability analysis of the closed-loop system is also conducted. Simulation results show that, small miss distances and smooth missile trajectories are achieved, and the system is robust against system uncertainties and external disturbances.

In this work, we present the design and fabrication of high-frequency SiC nanoresonators for highly sensitive nanoparticle sensing. A 280-nm single crystalline SiC film was grown on a Si wafer, and released from the substrate using an isotropic dry etching process. The SiC nanoresonators were then formed using the Focused Ion Beam technique. The simulation results show that the as-fabricated resonators can be thermally actuated at a very high in-plane resonant frequency of 366.11 MHz, and utilized as sensitive nano-particle sensing elements with a high mass sensitivity of 233 kHz/femtogram. These data indicate the possibility of developing SiC nanoresonators for high-resolution mass sensing and other high-frequency applications.

We report for the first time a highly sensitive paper-based tactile sensor using laminated graphite drawn on paper. Thanks to the high gauge factor of 26.2, as well as its excellent robustness and humidity-resistance, plastic-laminated graphite-on-paper has a high potential for mechanical sensors. Additionally, the plastic lamination combined with the laser cutting technique proposed in this study would enable the mass production of cleanroom-free fabrication and low-cost MEMS devices.