Pharmaceutical & medical
AN ARTIFICIAL HELPING HAND
Upper limb prosthetics are abandoned by some 18 per cent of patients, though some studies cite this figure as high as almost one in two. Evidently, replicating the complexity of human design in a comfortable, easy-to-use prosthetic is no easy feat. But developments in manufacturing and robotics technologies are offering patients a prosthetic experience like never before as Dave Walsha, sales manager at DC motor supplier EMS explains.
and the problem is amplified for those also missing hands or arms. Simple tasks such as opening a jar or tying a pair of shoelaces become difficult and time-consuming, leading to frustration and a decreased quality of life.
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As a result, extensive efforts have been made over the years to create prosthetic limbs that grant amputees more freedom and independence.
PROSTHETIC PRINCIPLES
There are two main types of prosthetic: passive and active. Passive devices are simply for aesthetic purposes, offering no additional movement. Active or powered devices are those that provide functionality to the limb.
Electrically powered prosthetics, or ‘myoelectric’ prosthetics contain electrodes to receive electromyographic (EMG) signals from the muscles or nerves above the amputation. It is these electrical
humans, whether it is their body
proportions or the nature of the
amputation means that no two users are the same - and therefore, neither should their prosthetics be. This makes component manufacturing hard to standardise, while also increasing the cost per prosthetic.
Another common concern is the lack of functionality. The human hand is able to grip
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rutches, walkers and wheelchairs offer some leg amputees additional support for movement. But these types of aids do not grant the same freedom as two working limbs,
signals that are transmitted to the prosthetic’s control electronics, where the signals are amplified and used to direct the motors to move accordingly.
PROSTHETIC PROBLEMS Despite the benefits prosthetics can offer, the technology still faces problems. Poor fit is a common problem reported by users, which can lead to discomfort, skin irritation and even causing some patients to abandon their prosthetic altogether. The highly individualised nature of
objects of a variety of shapes, sizes, and textures. This includes fragile items, which can be held tight enough to keep them secure but without damaging or breaking the object. Most commercially available bionic hands struggle to offer a comparable level of movement or sensory feedback and can therefore be a source of frustration more than an aid.
IMPROVING DESIGN
These issues represent a major challenge for designers, but there are ways to address them. Tackling fit and customisation issues, for instance, is possible by making use of 3D printing technologies. In recent years, advancements in 3D printing have made it more commercially viable to produce highly customisable products. With no minimum order or the need to create specific moulds, prosthetics can be prototyped and developed on an individual basis for an improved fit. This also allows for aesthetic personalisation for a less obtrusive prosthetic. To address functionality concerns, miniaturisation of the electronics within the prosthetic is essential. The DC motors that
January 2024 Instrumentation Monthly
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