Hand splints

Classification by type differentiates the coals acedg to the proportion of various plant ingredients and acedg to appearance. Standard types used in US include common handed, splint, cannel and boghead coals. 

FIGURE 35.3 The ARM Guide. The patient s arm is attached to a hand splint (S) that is attached to an orientable linear track. A dc servo motor (M) can assist in movement of the subject s arm in the reaching direction (R) along the linear track. Optical encoders record position in the reach (R), pitch (P), and yaw (Y) axes. A six-axis force sensor (F) records the forces and torques at the interface between the device and the subject. The device is statically counterbalanced with two counterbalance weights (C). 

This chapter presents preliminary investigations on the use of dielectric elastomer actuators as active eomponents of a specific type of orthotic systems, known as hand splints , used for finger or hand rehabilitation. 

Hand splints have today well established orthopedic applications as orthotic systems to immobilize either the entire hand or just one or more fingers. They can be adopted for different purposes, including post-surgical or post-trauma immobilizations and articulation-corrective or articulation-supporting actions. Such typical examples of uses refer to so-called static hand splints . More generally, hand splints can be divided aeeording to the scheme reported in Figure 24.1. 

This chapter is focused on dynamic hand splints , whose state of the art is briefly presented below. 

Figure 24.2 Examples of passive dynamic hand splints equipped with different passive components elastic bands ((a) Phoenix outrigger, adapted from [1], (b) LMB Wrist Extension Assist, adapted from [2]) linear springs ((c) Rolyan adjustable outrigger, adapted from 13]) and torsional springs ((d) DeROM Dynamic Range of Motion Wrist Splint, adapted from [4]).

The variation of the system compliance can be obtained in state-of-the-art passive dynamic hand splints by using either interchangeable elastic components (Figures 24.2a to 24.2c) or adjustable torsional springs (Figure 24.2d) these have to be respectively replaced or adjusted every time it becomes necessary. In order to avoid this, so-called active dynamic hand splints represent an attractive alternative. 

This chapter describes an actuated dynamic hand splint with variable compliance regulated by new DE contractile actuators. The concept is described below, with reference to Figure 24.4. 

Figure 24.4 Dynamic hand splints (top) example of a passive dynamic splint equipped with an elastic band (bottom) schematic drawing of the proposed concept the passive elastic band is substituted with active elastic actuators.

To develop a wearable dynamic hand splint with electrically variable compliance, the concept described here relies on the use of linear contractile DE actuators. The idea is to use these actuators as active elastic substitutes of the linear passive elastic components of traditional splints, as sketched in Figiure 24.4. 

The technical design of the splint and the related dimensioning of the actuators have necessarily to take into account, as a fundamental specification, the maximum antagonist force that the actuators should be able to offer. An analysis of the state-of-the-art of hand splints for finger rehabilitations showed a chronic lack of extensive and comparable data on suitable rehabilitation forces adopted in the clinical practice. However, as a special case. 

Figure 24.7 Design of a hand splint equipped with linear dielectric elastomer actuators, their high voltage electronics and a load cell.

Figure 24.9 Prototype dynamic hand splint equipped with silicone folded actuators, high voltage electronics and load cell.

Figure 24.10 Graphic interface of the control software developed for the hand splint.

Magnetic Resonance Imaging-Compatible Hand Splint... 

A new version of the hand splint is currently being developed in order to obtain a prototype compatible with the environment of Magnetic Resonance Imaging (MRl). An MRI-compatible hand splint could be used to perform rehabilitation exercises within an MRl scanner, so as to allow functional evaluations of the rehabilitation efficacy. 

The combination of these results provides a demonstration of the MRI compatibility of the actuators considered. Accordingly, this outcome encourages the development of MRI-compatible, easily wearable and cheap hand splints equipped with such a type of polymer device. 

Figure 24.16 Schematic drawing of the concept of a myoelectrically controlled hand splint. EMC signals are recorded by means of surface electrodes and are processed by a myoelectric controller that drives the actuators of the splint.

Future developments should be aimed at developing actuators with improved performances, in order to enlarge die admissible working range of the hand splint. Moreover, an MRI-compatible version of the system and an EMG controlled one are envisaged as further parallel developments. 

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