Browsing by Author "Hanson, William J."

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    CONDUCTIVE INSERTS TO ACQUIRE MYOELECTRIC SIGNALS THROUGH SILICONE LINERS
    (2008) Hanson, William J.
    Prosthetic socket liners provide both suspension and stability, and they do so best when they cover the remaining limb without breaks in the liner surface. This full coverage conflicts with the need to acquire myoelectric signals directly from the skin. Early solutions to this problem include windows in the liner and metal electrodes piercing and thereby weakening the liner. Windows compromise the integrity of the liner and often lead to discomfort at the edge of the window. Metal electrodes require attachment of external wires after donning. Another alternative is to mount cased electrodes in molded silicone receptacles. This may result in a proper seal, but it requires repeated removal of the electrode from the liner. The problems identified above can be addressed by passing the myoelectric signals directly though the liner with flexible Conductive Inserts. This approach allows metal electrodes in the outer socket to acquire the myoelectric signals as if they were in direct contact with the skin with no wires attached to the liner. LTI has developed Conductive Inserts that not only pass myoelectric signals through the liner but also allow for misalignment when the liner is inserted into the socket. These Inserts can be installed by prosthetic technicians in a commercial liner, or they can be built into a custom liner. With Inserts installed, a liner is a separate part that can be easily removed for cleaning.
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    NEW MYOELECTRODE OPTIONS
    (2005) Hanson, William J.
    Practitioners have been requesting improvements in myoelectrodes to facilitate better client fittings. Greater sensitivity, better immunity to external interference, more and better (linear) gain adjustment and good common mode rejection are all desirable features. Mechanical changes were also needed to create more cosmetically appealing sockets. Preamplifier cases had to be small and thin and provided with electrode cables of various lengths. When LTI designed their Remote Electrode System, they addressed all of these issues. This new remote electrode system has improved performance and low-profile packaging. The CavityBack™ Electrodes are available in three sizes/shapes, so the prosthetists can choose the best for their client. In addition to the cables for test sockets and soft socket liners, cables can be adapted for snap-on attachment to roll-on silicone sleeves.
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    NEW PROSTHETIC CONTROLLER EXPANDS CAPABILITIES
    (2002) Hanson, William J.
    The new VariGrip(tm) III Multi-Device Controller from LTI has expanded the capabilities of microprocessor-based prosthetic controllers. Traditionally, one or two prosthetic devices were controlled by two myoelectric input signals. This worked well for some people, but others could not master it and therefore they needed a different control strategy. The VariGrip solves this problem by offering a variety of pre-programmed control strategies. It allows prosthetists to set up systems to control up to four devices for greater versatility. Rather than restricting the user to myoelectrodes, the VariGrip III accepts inputs from myoelectrodes, Touch Pads, servo transducers or switches to fully utilize the user’s capabilities. The controller is compatible with all manufacturer’s single-motor terminal devices which further expands the options available to the prosthetist.
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    The Liberty Myoarraytm: A Diagnostic Tool To Test And Train Amputees To Use Myoelectric Prostheses
    (1993) Hanson, William J.; Smits, Matthijs P.; Teare, Peter R.
    When fitting a patient with a myoelectric prosthetic device, a prosthetist or therapist tests the patient to determine the best location on the muscle to place the electrodes Generally, the optimal location is the one where the myoelectic signal is strongest Typically, a prosthetist attempts to determine this location through trial-and-error,. This is time-consuming and the resulting signals are often inconsistent because each contraction is different. Others have proposed or utilized multiple electrodes for monitoring muscle activity and one research study resulted in a system to facilitate muscle-site identification. These systems however, depend on repetitive or sustained muscle contractions which may introduce another variable, misleading the prosthetist In addition, these approaches take significantly longer to perform and may tire the patient. The Liberty MyoArray* has been developed to provide an easy-to-use, portable diagnostic system for quickly measuring myoelectric signals from several locations at once, over a wide muscle area It increases the likelihood of proper patient fit and control of the prosthesis. For the experienced prosthetists, it speeds the process and it allows the inexperienced prosthetists to succeed with myoelectric technology It eliminates the possibility of error caused by variation in muscle flexions and facilitates training by providing feedback while the amputee is performing controlled muscle contractions.
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    USE OF PORTABLE SPECTROPHOTOMETER SOLVES COLOR MATCH PROBLEM
    (2008) Hanson, William J.
    Custom high-definition silicone restorations and cosmetic covers for prostheses are intended to match the appearance of the user’s sound-side limb. In addition to the physical characteristics, the cover must match the user’s skin color. This color match is a difficult process and traditionally has been done subjectively by the practitioner attempting to match standard color swatches to the patient’s skin tone. Ambient light and the practitioner’s judgment affect this process. A new portable spectrophotometer has been developed to solve this problem. It measures the color, removing the subjectivity from the process. These measurements have 5 times greater resolution than the color swatch approach. It also blocks ambient light and provides its own broad-spectrum light to assure a good color match across the entire optical spectrum. As a result, the color match will be good regardless of the lighting condition during the evaluation. This approach substantially improves the process, resulting in a better color match and greater acceptance by the user.