We developed a new hand-rehabilitation device,
termed the Digital Mirror Box, by introducing image pro-
cessing and information technology to a traditional mirror-box
therapeutic device. Here we describe the mirror-therapy mode
and the teaching mode, which are for training and evaluation
of the digital mirror box. However, these modes cannot be
applied to patients who have severe post-stroke disorders. To
compensate for this, we have developed a multi-balloon actuator
for application in force-stimulus feedback therapy. The actuator
is made of easily available material, generates large force, and
has characteristics suitable for hand rehabilitation.
When post-stroke paralysis occurs in the upper limbs,
keeping or recovering upper-limb mobility through training
exercise is especially important because arms and hands
are needed for many activities of daily living (ADL). Re-
habilitation systems using robots or virtual reality (VR)
technology have been suggested to be beneﬁcial ∼, and
are expected to allow quantitative evaluation, reproducible
training, and motivation for training. However, including
functional training for hands results in too many degrees of
freedom in the controller and the structure of the system is
complex and expensive.
In treatment for phantom-limb pain that is often experi-
enced by amputees, mirror therapy  has had favorable
outcomes. In mirror therapy, a mirror is set to hide the
amputated point and to show an image of the non-amputated
limb in its place. During therapy, the intended motion of the
amputated limb is thus given visually via the motion of the
non-amputated limb, as shown in Fig. 1. For patients with
cerebrospinal diseases like stroke, this method uses visual
feedback for relearning motor function, and is expected to
compensate for the mismatch between the physical model
in the brain and the real physical construction of the body.
Studies have reported the practical outcome  and that of
electrical stimulation to the paralytic hand  during mirror
therapeutic treatment, however the mechanism of recovery
is not clear. Another issue is that the simple mirror method
cannot quantitatively evaluate hand and ﬁnger motion. Never-
theless, because the major aspect of the therapy only requires
Fig. 1. Mirror box
visual stimuli, highly practical systems can be constructed,
which are simpler than robot-aided motion-training systems.
Kaneko et al. has proposed another system that applies a
computer to mirror therapy, without a large-scale robotic
system . Their study used a simple personal computer and
monitor, and suggested a vection function for recovery .
Ono et al. developed a brain-machine interface system that
includes monitoring electroencephalographic signals and an
active hand orthosis . However, they could not quantita-
tively evaluate hand and ﬁnger motion.
Our research aimed to improve on the simple mirror
box by developing a digital version –the digital mirror box
(DMB)– which utilizes image processing and information
technology, and that has an actuation function for ﬁngers
. This approach targets novel and rich functional re-
habilitation of the hand and ﬁngers, including functions
that conventional devices cannot address, such as motion
induction or assistance.
Here, we report three ways in which the DMB can be used
for therapy. The ﬁrst two are the mirror therapy mode and the
teaching mode, which are ways in which the DMB prototype
can be used for training and evaluation. However, patients
with severe paralysis who cannot readily make spontaneous
movements and who experience joint separations will not be
able to beneﬁt from these therapy modes alone. Therefore,
we also report a third therapy mode, haptic stimulus mode,
which uses a multi-balloon actuator (MBA) that induces
or assists with ﬁnger motion. We think the DMB can be
introduced to hospitals or daycare centers, and the MBA can
be added as an option for increasing the range of motor
disabilities to which the DMB can be applied.
Fig. 2. Digital mirror box
Fig. 3. Mirror image and overlaying.
via Multi-balloon actuator for advanced hand rehabilitation after stroke (PDF Download Available)