An acousto-optic sensor based on resonance grating waveguide structure.

This paper presents an acousto-optic (AO) sensor based on resonance grating waveguide structure. The sensor is fabricated using elastic polymer materials to achieve a good sensitivity to ultrasound pressure waves. Ultrasound pressure waves modify the structural parameters of the sensor and result in the optical resonance shift of the sensor. This converts into a light intensity modulation. A commercial ultrasound transducer at 20 MHz is used to characterize a fabricated sensor and detection sensitivity at different optical source wavelength within a resonance spectrum is investigated. Practical use of the sensor at a fixed optical source wavelength is presented. Ultimately, the geometry of the planar sensor structure is suitable for two-dimensional, optical pressure imaging applications such as pressure wave detection and mapping, and ultrasound imaging.

Design to Assist Better Youthhood for Adolescents with Lower-Limb Disability through Virtual Reality Sports.

Background: Youths with lower limb dysfunction display low levels of sports participation, which limits their growth and self-development, both physically and mentally. Recently, VR technology has proven its profound value in the psychological evaluation and treatment, rehabilitation, and immersive training of people in need. We have proposed, designed, and developed a VR rock-climbing game for youths with lower-limb dysfunction that allows them to engage in enjoyable and purposeful in-game tasks that simultaneously bring about intensive real-world exercise. Methods: Pilot studies were conducted on college students whose lower limbs were fixed to chairs. Heart rate monitoring, a flow questionnaire, interviews, and observation were conducted for each participant to evaluate the impact of the VR rock-climbing game. The collected data were trimmed on the basis of Cronbach's alpha and corrected item−total correlation (CITC) to guarantee the data's reliability. Results: The average value of each flow experience dimension was greater than 4 (0.76 < SD < 0.91). According to the flow-based analysis and the whole-process feeling distribution (WPFD), the evaluated study brought about the participants' happiness and a sense of mastery and achievement. Conclusions: By bringing about a deep and enjoyable immersion in VR, it remarkably promotes the participants' intention to participate in exercises.

A Bibliometric Analysis of Human-Machine Interaction Methodology for Electric-Powered Wheelchairs Driving from 1998 to 2020.

Electric power wheelchairs (EPWs) enhance the mobility capability of the elderly and the disabled, while the human-machine interaction (HMI) determines how well the human intention will be precisely delivered and how human-machine system cooperation will be efficiently conducted. A bibliometric quantitative analysis of 1154 publications related to this research field, published between 1998 and 2020, was conducted. We identified the development status, contributors, hot topics, and potential future research directions of this field. We believe that the combination of intelligence and humanization of an EPW HMI system based on human-machine collaboration is an emerging trend in EPW HMI methodology research. Particular attention should be paid to evaluating the applicability and benefits of the EPW HMI methodology for the users, as well as how much it contributes to society. This study offers researchers a comprehensive understanding of EPW HMI studies in the past 22 years and latest trends from the evolutionary footprints and forward-thinking insights regarding future research.

Elastomeric Polymer Resonant Waveguide Grating based Pressure Sensor.

In this paper, we demonstrate an elastomeric polymer resonant waveguide grating structure to be used as a pressure sensor. The applied pressure is measured by optical resonance spectrum peak shift. The sensitivity - as high as 86.74pm/psi or 12.58pm/kPa - has been experimentally obtained from a fabricated sensor. Potentially, the sensitivity of the demonstrated sensor can be tuned to different pressure ranges by the choices of elastic properties and layer thicknesses of the waveguide and cladding layers. The simulation results agree well with experimental results and indicate that the dominant effect on the sensor is the change of grating period when external pressure is applied. Based on the two-dimensional planar structure, the demonstrated sensor can be used to measure applied surface pressure optically, which has potential applications for optical ultrasound imaging and pressure wave detection/mapping.

Polymer waveguide grating sensor integrated with a thin-film photodetector.

This paper presents a planar waveguide grating sensor integrated with a photodetector (PD) for on-chip optical sensing systems which are suitable for diagnostics in the field and in-situ measurements. III-V semiconductor-based thin-film PD is integrated with a polymer based waveguide grating device on a silicon platform. The fabricated optical sensor successfully discriminates optical spectral characteristics of the polymer waveguide grating from the on-chip PD. In addition, its potential use as a refractive index sensor is demonstrated. Based on a planar waveguide structure, the demonstrated sensor chip may incorporate multiple grating waveguide sensing regions with their own optical detection PDs. In addition, the demonstrated processing is based on a post-integration process which is compatible with silicon complementary metal-oxide semiconductor (CMOS) electronics. Potentially, this leads a compact, chip-scale optical sensing system which can monitor multiple physical parameters simultaneously without need for external signal processing.