Distracted driving is one of the main causes of vehicle collisions in the United States. Passively monitoring a driver's activities constitutes the basis of an automobile safety system that can potentially reduce the number of accidents by estimating the driver's focus of attention. This paper proposes an inexpensive vision-based system to accurately detect Eyes Off the Road (EOR). The system has three main components: 1) robust facial feature tracking; 2) head pose and gaze estimation; and 3) 3-D geometric reasoning to detect EOR. From the video stream of a camera installed on the steering wheel column, our system tracks facial features from the driver's face. Using the tracked landmarks and a 3-D face model, the system computes head pose and gaze direction. The head pose estimation algorithm is robust to nonrigid face deformations due to changes in expressions. Finally, using a 3-D geometric analysis, the system reliably detects EOR.The proposed system does not require any driver-dependent calibration or manual initialization and works in real time (25 FPS), during the day and night. To validate the performance of the system in a real car environment, we conducted a comprehensive experimental evaluation under a wide variety illumination conditions, facial expressions, and individuals. Our system achieved above 90% EOR accuracy for all tested scenarios.Index Terms-Driver monitoring system, eyes off the road detection, gaze estimation, head pose estimation.

has been a challenge. [5,6] To enhance the absorption and photoresponse of graphene devices, researchers provide a series of strategies to interface graphene with light-absorbing semiconductors. [7][8][9][10][11][12][13][14][15][16] Early experimental studies on hybrid devices mainly focus on using one semiconductor layer, including colloidal quantum dots, [7,8] perov skites, [9] organic polymers, [10] single crystals, [16] 2D materials, [17] silicon, and other traditional materials. [11] More recently, improvement of device performance has been made by introducing PN junction bilayer absorbing layer. Incorporating graphene with a perovskite/ organic heterojunction or organic PN junction [14,15] is reported to improve both the photo responsivity and bandwidth. However, the limited narrow spectral range of light-absorbing layer causes ultrahigh photoconductive gain but at the same time sacrifices the detection spectral range. [18] In addition, a number of chemical approaches have been reported to synthesize the conjugated polymers/small molecules (typically with a bandgap of less than 1.6 eV) with appropriate energy gap and desirable photoelectric properties, but the device performance is still restricted. [19] So far the spectral range of graphene-based high gain photodetection is limited to typically 400-700 nm. [9,10,14,15,20,21] Herein, we explore a broadband (405-1550 nm) graphene/ organic semiconductor heterojunction phototransistors with bi-directional photoresponse (both positive and negative photocurrents) for the first time. Instead of broadening the absorption range of the semiconductor layer, our devices exploit ultrasensitive photoresponse at visible region, and the inverse photoresponse at near-infrared region without the need for cryogenics or adjusting gate voltage. Taking organic small molecule C 60 /pentacene heterojunction as the light-absorption layer, we achieve a highest responsivity of 9127 A W −1 , response time down to 275 µs, and external quantum efficiency up to 11.5% in visible regime and over 1800 A W −1 (0.063%) in near-infrared regime. Compared with previous work, our phototransistors not only have large built-in electric field at the C 60 /pentacene interface for high quantum efficiency, but also maintain an ultrasensitive response to the near-infrared region. The wavelength-dependent bi-directional response enables us to analyze the device mechanism. Our devices have potential applications in hyperspectral imaging.A graphene-semiconductor heterojunction is very attractive for realizing highly sensitive phototransistors due to the strong absorption of the semiconductor layer and the fast charge transport in the graphene. However, the photoresponse is usually limited to a narrow spectral range determined by the bandgap of the semiconductor. Here, an organic heterojunction (C 60 /pentacene) is incorporated on graphene to realize a broadband (405-1550 nm) phototransistor with a high gain of 5.2 × 10 5 and a response time down to 275 µs. The visible and near-infrared parts of the photor...

In this paper, a high‐performance pressure sensor that imitates the sensing functions of human skin is proposed. A rough poly(3,4‐ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) film transferred from abrasive paper acts as the sensing layer, while silver nanowires deposited on the bottom Ecoflex film with a 3D microstructure serve as the electrodes. Because of the bionic hierarchical structure, the resulting sensor exhibits a high pressure sensitivity of 6.13 kPa−1, low limit of detection (20 Pa), low operating voltage (0.1 V), and broad sensing range (up to 90 kPa). Furthermore, as the sensor is ultrathin, ultraflexible, and stretchable, it can easily conform to the uneven surface of human skin to allow monitoring of physical signals from the human body or detect the tactile stimulation of objects. In addition, a sensor array consisting of 4 × 4 pixels is assembled to realize the precise mapping of spatial pressure distribution. By virtue of its superior performance and low‐cost fabrication, the proposed pressure sensor may potentially be applied to next‐generation wearable devices such as e‐skin, soft robotics, and human–machine interaction systems.

A new method, Fe/Mg co-doping, is proposed for the first time to optimize thermochromic VO2 and the promising performance of VO2-based smart windows for practical applications is successfully achieved.