Varifocal lenses are a lens with different focal lengths and, therefore, magnification. These are used extensively in the optics industry as progressive lenses in eyewear. A focal length gradient exists along the lens height, so objects magnify as the user looks downwards. Unfortunately, progressive lenses are rigid materials making them closer to quasi-varifocal lenses. In this present study, varifocal lenses can change focal length to a constant value. This study investigates polyvinyl chloride (PVC) gel and Electrohydraulic Actuators Powered by Induced Interfacial Charges (EPIC) actuators as varifocal lenses. Polyvinyl chloride (PVC) gels are a new type of dielectric elastomer actuator only investigated at the start of the century. The transparent gels are known for producing displacement under an effective voltage in a mechanism known as anodophilic creep, the axisymmetric tendency to deform towards the anode surface. The EPIC actuator is a novel application of PVC gels that places
These electroactive gel polymers, commonly PVC-based, have been widely studied regarding their actuation abilities. As far as electromechanical theory, the currently accepted mechanism for polymer gel actuation has been primarily attributed to mobile plasticizer migration towards the space charge layer near the anode. The anodophilic nature of the plasticizer provides a variety of potential applications, largely dependent on electrode geometry and configuration. As an artificial mechanotransductor however, the current hypothesis of a polymer gel’s sensing mechanism has been recently attributed to the phenomenon known as Langmuir adsorption. Upon applying a compressive strain to these soft sensors, plasticizer will exhibit migration towards the polarized adsorbed layer at the electrode interface. In this study, an application-based approach is considered to further exercise the content of the suggested polymer gel MET theory. Due to its compliant nature, the polymer gel sensor (PVC and
Biomimicry is the art of robotics mimicking systems in nature and could potentially include evolutionarily optimized skin and nervous systems of living organisms. This potential artificial skin application for soft polymeric gel sensors may be used in damaged skin replacement, prosthetics, or other soft robotic applications. Characterization of polyvinyl chloride (PVC) sensing in static planar orientations has been performed in prior studies. However, further testing is required to understand this mechanoelectrical transduction and its dependence on surface orientation and loading condition. PVC gel sensing capabilities under varying surface morphologies and loading conditions are unknown. This characterization is critical because it will determine practical operating conditions and applications for PVC gel sensors. The goal of this study is to analyze the electrical response of PVC gels in planar and curved surface orientations at static and dynamic loading conditions with novel elect
Polyvinyl chloride (PVC) gels have been shown to exhibit mechanoelectrical transduction under varying mechanical inputs. These inexpensive gels can easily be fabricated into planar sections with differing amounts of plasticizer. The plasticizer content within the gel samples can be tuned for optimal mechanoelectrical transduction under expected force inputs. More plasticizer content results in more sensitive gels with lower mechanoelectrical saturation levels, less plasticizer is more ideal for higher expected force inputs. Higher plasticizer content has shown these gels to be very sensitive, providing mechanoelectrical transduction under sub-gram force compressive inputs. By using segmented electrodes these gels can sense both location and magnitude of incoming forces in planar and quasiplanar applications. Different orientations of electrodes are investigated for varying purposes. A square planar sensor with a 3x3 grid of square electrodes is investigated and resolution of this planar sensor is tested with varying force magnitudes and locations. Raw mechanoelectrical responses are shown and a simple application is displayed with some integrated electronics for data acquisition and processing. Some limited work in quasiplanar orientations is also investigated on curved and angled surfaces. This work also provides some insight to the mechanics of mechanoelectrical transduction within PVC gels. The mechanoelectrical transduction has been found to be a surface property, however this study examines the area of contribution to the overall mechanoelectrical transduction. Further experimentation aims to broaden the applications of these sensors.
Fused deposition modeling (FDM) is a widely implemented manufacturing technique typically used for rapid prototyping of custom components or geometries. Unfortunately, FDM printers are often limited by build volume, print quality, and print time. Build volume is traditionally fixed, such that components larger than a given printer volume must be printed separately as segmented components, and subsequently bonded to one another. Beyond the limitations of the build volume, the quality of prints is another key concern. The components that make up a larger 3D printer often cannot produce the fidelity of a smaller precise printer, thus limiting the device to solely larger components. Print time is also a function of the previous limitations; a faster print will typically have lower quality and a smaller print will often print quicker.
This project seeks to address the limitations of a traditional FDM printer through the development of a modular 3D printer. Standard 3D printers operate with a rigid metal frame that inhibits the freedom to increase the print volume. The design proposed would allow a 3D printer to expand or contract in build volume while also allowing the user to customize needs depending on requirements of print fidelity or print time. The modularity further allows for compact storage and the ability to be transported for on-site prints, which would be particularly useful for wearables and orthopedic adjustments for athletics or within the medical field.
In fact, compact storage size to maximum expanded printer size aims to be a 1 to 10 ratio. The design is self-printing, in that frame components are manufactured from the printer itself, to elongate the dimensions, without sacrificing print fidelity. Any desired build volume can be easily accommodated by printing additional frame components. Such a design is ideal for custom wearables or large-scale projects where a rigid printer structure occupies excessive space. This could prove especially useful for astronauts where cargo shipments are dependent on volume and mass or in fields where custom-fitted wearables are required, such as in athletics or the medical field.
Polyvinyl chloride (PVC) gels have been studied in some detail and exhibit mechanoelectrical transduction properties, making these materials suitable for sensing applications. This study aims to investigate these mechanoelectrical properties through mathematical modeling. A nonlinear gray-box hybrid state space approach can accurately model the mechanoelectrical transduction properties of the PVC gel sensor in both transient and steady state responses. This approach studies multiple nonlinearities in both transient and steady state mechanoelectrical responses such as overshoot variation and signal attenuation. Mechanoelectrical polarity inversion for tensile/compressive loading schemes exhibited in experimental testing is also investigated in the nonlinear model. A simplified linearized model also shows accurate results for the linear region of mechanoelectrical responses in the PVC gel sensors. Further mathematical modeling aims to describe some underlying physics and governing equations of the mechanoelectrical properties of PVC gel sensors.
Catheters are commonly used in many medical procedures. These catheters require a high skill to navigate through human blood vessels and also require the use of an X-ray machine to guide the user. Active catheters have been fabricated and studied to increase the dexterity of the catheter, making the catheter much easier to use. Ionic polymer-metal composites (IPMCs) have been studied for this application. IPMCs exhibit large deformations under relatively small voltages (<5 V) making IPMCs excellent candidates for this application. One disadvantage of IPMCs is low stiffness, making the tip of the catheter hard to control in a blood stream. Hydraulic powered active catheters have also been studied. These hydraulically powered active catheters offer higher stiffness but are difficult to control. This research aims to combine these two actuation types into a single hybrid actuator. This will potentially create an active catheter capable of precise complex motion that is safe for human use.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.