In this paper, in order to improve the sensitivity of tactile sensor, we proposed and demonstrated a fiber in-line Mach-Zehnder interferometer (MZI) sensor for the measurement of grasp force. The sensor was fabricated by splicing a section of few-mode fiber (FMF) between two single mode fibers (SMFs). The simulation using Rsoft software shows that the sensor has the best performance with the FMF length is 10mm and the core offset is 5um. The mechanical strength of the sensor is improved by using heat shrink tube at the point of optical fiber fusion splicing. The MZI sensor is embedded in the gripper and the force calibration is carried out by using the piezoresistive sensor. The experiment shows that the sensitivity of the sensor is about 6nm/N. The sensor has many advantages including simple fabrication, low cost, and high sensitivity, demonstrating its great application potential in the fields of Human Machine Interface.
Robotic grippers combined with visual-touch sensor fusion have been widely used in the manufacturing industry. However, due to limited control of the force applied to the mechanical gripper, it is hard to achieve stable object grasping. Therefore, to control the force of gripping objects, we propose a robotic rotary gripper fused with light detection and ranging (LiDAR)-tactile. We use LiDAR to obtain distance information and fiber Bragg grating as the tactile sensor for force feedback. In order to ensure the low-loss transmission of the optical signal in the rotation process, the fiber optic rotary joint is employed and assembled into the system. Finally, the experimental results show that our proposed system can achieve a stable grasp of objects with different shapes by precisely controlling the force, which can meet the demands for precise robotic grasping and fast manipulation.
Three-dimensional (3D) perovskite photodetectors (PPDs) demonstrate remarkable photoelectric detection ability, but the intrinsic instability of 3D perovskite films against moisture, oxygen, and temperature has been a roadblock for achieving great stability and reliability of the resulting PDs, which can be mainly ascribed to the inevitable defects on surfaces and grain boundaries that can incur nonradiative charge recombination to impair device performance and initiate the degradation of perovskites. In this work, we introduced the two-dimensional (2D) perovskite material PEAI to fabricate a high-performance and stable 2D/3D stacked PPD. As a result, the responsivity of the PEAI processed PPD (PEAI-PPD) reached 1.19 A/W under the illumination of 532 nm laser with the power density of 5 μW/cm2 at bias voltage of −1 V, and retains 80.15% of the initial value after 16 days of nonencapsulated storage at 10%-15% relative humidity (RH). Our work provides a simple and effective method for the fabrication of high-performance and stable 2D/3D stacked PPDs, which has great application potential in visible light communication, imaging and environmental monitoring under complex environmental conditions.
Cardiovascular disease is a major risk to human health, which needs long-term monitoring for prevention and early diagnosis. Optical sensors present the advantage of immunity to electromagnetic field and high sensitivity, and have been growing in a variety of emerging medical applications to monitor human cardiac parameters. Most of the current optical sensors can only measure limited cardiovascular information such as the heart rate, therefore, the optics-based approach for cardiac electrophysiology has attracted the attention of more researchers. In this paper, we developed a method to evaluate the availability of our proposed anti-EMI optical sensor. The sensitivity of optical sensor based on electro-optic modulation can achieve 266.4μW/V and detect the electrocardiogram (ECG) by attached to the chest and edge of clavicle. A series of ECG signals over 1 hour were analyzed using proposed method, which is driven by the optimization of R-peak location, Lorenz plot and statistical correlation. ECG monitoring results of the optical sensors are in accordance with a standard clinical device (SOMNOtouch™ RESP) among different subjects. Moreover, both the sensors are tested in daily electromagnetic conditions, and it causes some obvious signal artifacts to the SOMNO system, but almost no effect on the optical sensors during the long-term test. We provide further grounds for such clinical applications by demonstrating, for the first time to our knowledge, optics-based device used in long-term ECG monitoring, an essential tool in modern cardiac monitoring applications.
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