The ability to manufacture complex 3D-objects directly from its CAD model is the important reason why additive manufacturing is being widely used to fabricate cost-efficient prototypes and preferred over conventional manufacturing methods. Moreover, it portrays as a bridging technology to connect different scientific and industrial fields, e.g. Engineering, Medicine, etc. Consequently, additive manufacturing finds its applications in the production of patient-specific orthoses. This paper discusses the development of a pressure sensor based on an optical waveguide principle manufactured using stereolithography apparatus process to embed into a below-knee orthosis. For Orthopedic patients, the below-knee orthosis must be adjusted to the lower leg at regular intervals due to anthropometric changes in patient’s body to achieve proper mobility and correct load. Currently, this alteration relies on the patient’s estimation of support load which is only sub-optimal. Hence, the concept of developing an intelligent orthosis with a novel embedded optical system to monitor the exact support load at the neuralgic is proposed.
This paper proposes an innovative approach of manufacturing optical fibers using nozzle-mask-aided additive manufacturing. Nozzle-masks ease 3D-printing of optical fibers allowing the manufacturing or drawing of optical fibers of up to 10 μm diameter. These nozzle-masks feature a suction mechanism to prevent clogging of printhead and mask. The extrusion of Polymethyl-methacrylate material through the print-head and nozzle-mask simplifies the rapid prototyping of the optical fibers.
Additive manufacturing enables direct prototyping of complex 3D-objects that are difficult to manufacture using conventional methods. It is widely used to fabricate cost-efficient prototypes and portrays as a bridging technology to connect different scientific and industrial fields, e.g. Engineering, Medicine, etc. Consequently, additive manufacturing finds its applications in the production of patient-specific orthoses. This paper discusses the application of the stereolithography apparatus process to develop a pressure sensor based on an optical waveguide principle to embed into a below-knee orthosis. For Orthopaedic patients, the below-knee orthosis must be adjusted to the lower leg at regular intervals due to anthropometric changes in patient’s body to achieve proper mobility and correct load. Currently, this alteration relies on the patient’s estimation of support load and is only sub-optimal. Hence, the concept of developing an intelligent orthosis with a novel embedded optical system to monitor the exact support load at the neuralgic is proposed.
Visible light communication (VLC) allows the dual use of lighting and wireless communication systems by modulation of illumination devices. However, to increase the performance, typically, beam-forming measures are taken creating pencil beams, thus contradicting the illumination purpose. In order to optimize the performance trade off between efficient illumination and communication, the switching capabilities of illumination LEDs are examined. Illumination LEDs with standard drivers and without beam-forming show limited applicability for communication purposes as they are not optimized for the necessary switching capability (f ≈11 MHz) and coherence. Methods to enhance the electrical current by pre-equalisation, biasing, carrier sweeping and current shaping are examined in respect to the illumination LED's communication performance. A novel driver scheme is derived which achieves considerably higher switching frequencies (f ≥100 MHz) without employing beamforming at the illumination LED. This driver is able to obtain a data rate of up to 200 Mbit/s at a distance of 3.2 m, using on-off keying (OOK) modulation technique. Therefore, it is feasible to apply the LED driver by implementing standardised illumination devices in VLC systems.
Additive manufacturing (AM) and rapid prototyping process (RPP) have revolutionized the production of 3D objects in the last few decades. RPP has considerably increased the rate of production and the possibility of manufacturing prototypes in the fields of electrical, optical, and mechanical engineering. The manufacturing of optical prototypes including spherical, aspheric, and special kinds of lenses and lens arrays has reformed the fabrication of optical components. In this paper, specifically designed lens array prototypes for application in visible light communication (VLC) are introduced. These lens array prototypes are manufactured using the stereolithography apparatus (SLA) process. These lens arrays are designed to achieve optimal transmission of the light beam for VLC systems. One of the prototypes from the lens arrays contains primarily four spherical lenses and one thicker convex lens and the other contains one fresnel lens as a substitute for thicker convex lens. These lens arrays are further post-processed to achieve the required transparency. These lens array prototypes are tested using laser and LEDs. The ON-OFF keying modulated light beam was transmitted through the lens array at the sender side and focused on the photo-receiver using another lens array at the receiver side which is 200 cm apart. After evaluating these lens prototypes, it can be concluded that with appropriate post-processing and high-resolution stereolithography based manufacturing, a low data rate VLC link can be formed.
Additive manufacturing (AM) has provided a new aspect of manufacturing 3D objects in the past few decades. The use of AM for the production of 3D objects has accelerated the rate of designing and manufacturing. These AM techniques can be utilized in manufacturing optical, mechanical and electrical prototypes. The manufacturing of optical prototypes involves the production of spherical lens prototypes and special forms of aspheric and concentrator lenses such as fresnel lens prototypes. Different designed fresnel lens prototypes are manufactured using a transparent clear resin material and stereolithography apparatus (SLA) process. It uses a photochemical process to develop 3D structures. These manufactured fresnel lens prototypes are difficult to postprocess using hand polishing, hence they are post-processed using lacquering to get more transparency. These prototypes are tested using a laser source to evaluate the attenuation of light and focal length of manufactured fresnel lens prototypes. Similar tests using a commercially available convex lens of the same focal length are carried out. The results of these tests show that the difference between the mean of attenuation of light beam when passed through a fresnel lens prototype and the convex lens is 1 dB. The focal length of manufactured fresnel lens prototypes has a 10 mm deviation. Therefore, it is feasible to manufacture complexity and cost reduced fresnel lens prototypes using SLA and lacquering.
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