Positively advocating that low-cost additive 3D-printing technologies and open-source licensed software/hardware platforms represent an optimal solution to realize low-cost equipment, a mechanical and 3D-printable device for bilateral upper-limb rehabilitation is presented. The design and manufacturing process of this wheel-geared mechanism, enabling in-phase and anti-phase movements, will be openly provided online with the aim of making a set of customizable devices for neurorehabilitation exploitable all over the world even by people/countries with limited economical and technological resources. In order to characterize the interaction with the device, preliminary trials with EMG and kinematics recordings were performed on healthy subjects.
Positively advocating that low-cost additive 3D-printing technologies and open-source licensed software/hardware platforms represent an optimal solution to realize low-cost equipment, a mechanical and 3D-printable device for bilateral upper-limb rehabilitation is presented. The design and manufacturing process of this wheel-geared mechanism, enabling in-phase and anti-phase movements, will be openly provided online with the aim of making a set of customizable devices for neurorehabilitation exploitable all over the world even by people/countries with limited economical and technological resources. In order to characterize the interaction with the device, preliminary trials with EMG and kinematics recordings were performed on healthy subjects.
Stroke is one of the main causes of long-term disability in the world. According
to the World Health Report 2002 from the World Health Organization (WHO), 15
million people suffer stroke worldwide each year. Of these, 5 million die and
another 5 million are permanently disabled. In the Western countries stroke is
the first cause of permanent disability.[1] The total number of affected people in Europe is estimated to be about
9.6 million, with an annual increase estimates soaring from 1.1 million in 2000
to more than 1.5 million in 2025.[2] In the United States (US), approximately 795,000 people suffer a stroke
each year. The national financial and public health burdens of chronic stroke in
the US alone were estimated at $65.5 billion in 2008.[3] Within this global framework, neurorehabilitation has the important aim
of improving conditions of patients and mitigate the social and economic burden
of stroke.[4] In fact, the economic burden on health systems of stroke only adds up to
the load of personal disability and exclusion producing detrimental effects in
the affective and social domains. Moreover, growth and ageing of the population
demand an increase in healthcare staff involved in neurorehabilitation. Such a
situation urges to the prompt identification and adoption of low-cost and
home-oriented solutions enabling a rationalization of the health service
resources. A rehabilitation based on the use of low-cost devices also meets the
needs of low-income countries where the healthcare system is lacking and the
medical personnel is insufficient. In these countries, where even hospitals
cannot afford the purchase of expensive mechanical devices, the challenge is to
conceive and develop low-cost and easily-replicable systems for
rehabilitation.
Low-cost devices for upper-limb rehabilitation
In the Western countries, stroke rehabilitation centers can take advantage by
exploiting advanced robotic devices specifically designed to maximize functional
recovery. After stroke, during the acute and part of the sub-acute phase,
patients typically benefit of a period of hospitalization. During this time
neuroplasticity, simply said the ability of the brain to recover by creating new
neural synapses and pathways, is maximum. Therefore, it is important to
stimulate this process properly with interventions based on intensive and
repetitive movement training. Rehabilitation robots represent an optimal
solution to the problem. However, neuroplasticity is a never-ending process and,
even if diminishing with time, can occur and play a relevant role even some
years after stroke, in the chronic phase of the disease.[5] Therefore, rehabilitation should not be limited to the first months
following stroke but has to become a permanent issue involving the entire life
of people with stroke. This said, robots are not suitable for home
rehabilitation because of their high costs and dimensions. Cheaper, easier to
use and more widely affordable solutions to enable intensive and repetitive
movement training must be found. Various passive devices for upper-limb (UL)
home rehabilitation have been developed and are commercially available.[6] Among these the Tailwind[7] the Reha-Slide, and the Reha-Slide Duo (Nudelholz)[8] are interesting solutions because they enable a bilateral arm training.
In fact, if on one hand both unilateral and bilateral training improve UL
function by similar amounts,[9] on the other, initial clinical results indicate that bilateral training
may have a surplus value for some groups of strokepatients.[10] Even more importantly, stroke does not provoke only a unilateral loss of
motor control but may affect also the ability for inter-limb coordination.[11] In these patients the recovery of the ability to perform bimanual tasks
of activities of daily living (ADLs) is a main goal and bilateral training
becomes an issue. Unfortunately the cost of passive mechanical devices presented
above is low but not negligible: cheaper and more widely affordable solutions
based on 3D-printing and hw/sw open-source distribution are needed.
Open-source technologies for health
Many countries, due to social and economical issues, often lack resources to
support appropriate health technologies necessary for the prevention, diagnosis,
and treatment of many curable diseases.[12] WHO acknowledges that most of the current global health targets and goals
would be impossible to achieve without an increase in access to essential
medical devices,[13] hence promotes the development and local production of appropriate applications.[14]In the past few years, information technology has had a disrupting impact on
healthcare thanks to the diffusion of so-called open-source licenses.[15] Among those projects we can find: KwaMoja,[16] a low-cost management system currently used by hospitals in Tanzania and
Kenya; GNU Solitario,[17] a hospital information system used particularly in poor areas; Drupal,[18] a popular content management system (CMS) for websites which has been
modified to create Mercy Health, a portal used by more than 700 clinics.Progressively, the same approach also found application in the hardware field and
concrete examples of open-hardware biomedical devices are rapidly increasing.
Eye tracking systems which facilitates life to paralyzed people, developed for
$100 instead of the traditional systems at $7000.[19] The Open Source for Biomedical Engineering (OS4BME) project in which,
during the Innovator Summer School 2013, Kenyan students designed and assembled
an open-source neonatal monitor.[20] The Generic Infusion Pump project, a drug-delivery system born as a
collaboration between the University of Pennsylvania and the FDA.[21] BITalino,[22] a hardware platform used in the management of biosignals like EMG, EEG,
and ECG. Libelium,[23] a project for the management of biometric parameters such as blood
pressure, blood glucose, and saturation. OpenBCI,[24] an interface for projects requiring the use of the EEG signal. And also
WIL, a mechanical prosthesis finalized to compensate the lack of the limb
involving a drive which is managed by the movement of the wrist and by a system
of rods; FABLE, an electromechanical prosthesis intended for those who have
suffered amputation or are suffering from congenital malformation; BOB, a
neonatal incubator aimed to reduce neonatal deaths in poor countries.[25]
Use and clinical rational
Bilateral UL training is a relatively new form of stroke rehabilitation. It is based
on the premise that, during simultaneous movements, the non-paretic UL may support
the movement of the paretic UL at brain level. The interest in this therapy, which
is becoming more and more common, arose partly accidentally[26,27] and partly
from insights, gained from the motor control literature. In this literature,
rhythmic interlimb-coordination studies investigated extensively coupling and
interaction effects between the two ULs in healthy subjects.[9] It was well proved that human beings do show a basic tendency towards
in-phase (i.e. symmetrical movements) or anti-phase (i.e. alternating movements)
coordination, with a prevalent 1:1 frequency locking mode for UL bilateral movements.[28] The tendency towards these patterns reflects the coupling between the ULs. In
bilateral UL training, this coupling is exploited using interactions between both
sides of the central nervous system through intact connecting structures, such as
the corpus callosum.[29,30]In this work the authors are presenting the current version of DUALarm (Figure 1), a low-cost,
open-source and 3D-printable rehabilitation device based on a geared mechanism
(Figure 4) enabling
in-phase (i.e. symmetrical) and anti-phase (i.e. alternating) movements and
developed to support reaching rehabilitation movements of the UL (Figure 2).
Figure 1.
DUALarm—a low-cost, open-source and 3D-printable device for upper limb
neurorehabilitation.
Figure 4.
DUALarm 3D-printed core mechanism based on a plastic structure (white)
and containing five wheel-gears divided in three groups: fixed gears
(green), mobile gears (red), and the inversion gear (white).
Figure 2.
Schematic representation of selected targeted bilateral movements
(in-phase and anti-phase). The orientation of the two rotation axes of
the DUALarm mechanism is represented in red and green. (a) Front view;
(b) rear view.
DUALarm—a low-cost, open-source and 3D-printable device for upper limb
neurorehabilitation.Schematic representation of selected targeted bilateral movements
(in-phase and anti-phase). The orientation of the two rotation axes of
the DUALarm mechanism is represented in red and green. (a) Front view;
(b) rear view.DUALarm 3D-printed core mechanism based on a plastic structure (white)
and containing five wheel-gears divided in three groups: fixed gears
(green), mobile gears (red), and the inversion gear (white).
DUALarm
DUALarm has been designed in order to take the most of 3D-printing technology,
limiting as much as possible the number of commercial components. The version
presented in Figure 3 is an
almost-completely 3D-printed plastic (PLA) device, equipped by two handles (one for
each side) held by the subject and standing upon a regular table, with an optional
clamp to fix it. An optional shield could be mounted in front of the core mechanism
of the device, in order to protect the hands or the fingers of the patient while
performing the exercise. Parts which can be easily and inexpensively found on the
market (like screws, bolts and cylindrical rods) have not been thought to be
3D-printed in this project in order to maximize their performance and minimize the
time needed to produce the device.
Figure 3.
Front and rear view of DUALarm. The images show the mechanical nature of
the device, which is completely 3D printed and unactuated. The only
electronic element inside the device is an Arduino UNO board, visible in
the rear view.
Front and rear view of DUALarm. The images show the mechanical nature of
the device, which is completely 3D printed and unactuated. The only
electronic element inside the device is an Arduino UNO board, visible in
the rear view.
Core mechanism
The core mechanism is made up of: a properly supported gearbox, a mode-selection
mechanism, and a signal acquisition system. The pivotal component of the device
is the mechanism of the gearbox, based on a plastic structure and containing
five wheel-gears and three aluminum shafts (10 mm in diameter). Referring to
Figure 4, three
groups of gears are recognizable: the fixed (hereafter f) group
rotating about a and made up of gears
g, g,
g stationary constrained to an aluminum
shaft, the inversion gear g rotating about
a and the mobile
(hereafter m) group rotating about
a and made up of gears
g, g,
g. All the gears are mechanically
constrained to three aluminum shafts, and secured by steel screws and bolts to
avoid free spinning. The gap between g and
g is different from the one existing
between g and g.
Shaft a is free to move axially in order to obtain
two different configurations of the mechanism and let gears engage differently
(Figure 5).
Consequently, sliding up and down the m group, two different
configurations can be selected: if g engages
g, a and
a perform anti-phase rotations; if
g engages g,
a and a
perform in-phase rotations, thanks to the presence of
g. All the gears in the mechanism are 2 mm in
module to guarantee a good mechanical resistance and have a double chamfer in
order to ease the engagement of the gears. A selection mechanism
s, made up of a 3D-printed lever, is placed above the
gears. If it is engaged, it works as a spacer that causes
g to engage g,
leading to the anti-phase rotation of a and
a. If it is not engaged,
g is engaged with
g through g,
leading to an in-phase rotation of shafts. An aluminum pin p
(with a 3D-printed cup) locks the position of s for safety. To
track the movement performed by the patient, the mechanism is equipped with two
potentiometers, measuring a and
a rotations through two pairs of gears
( and ) to compensate the vertical sliding of
a: the first element of each couple is spliced
and secured to the rod by a steel screw and bolt, the second one is simply
spliced onto the slotted-shaft of the potentiometer. On the back-side of the
device an Arduino Uno R3 board is located while two
potentiometers g and
g are accommodated into the base (Figures 3 and 5).
Figure 5.
Schematic representation of DUALarm gear mechanism layout in both
in-phase and anti-phase configuration.
Schematic representation of DUALarm gear mechanism layout in both
in-phase and anti-phase configuration.
DUALarm reaching version
In the DUALarm configuration shown in Figure 3, two arms are connected to axis
a and a. Each
arm is made up of one handle, one aluminum rod (about which the handle is free
to rotate) and two links connecting the shaft of the wheel-gears to the handle.
Because of the slight sliding movement of a to
select the required configuration, every arm includes a spacer that can be
placed above or below the handle in order to maintain the left and right handles
at the same height. Links are constrained to the shafts of the core mechanism
thanks to a friction-based connection tightened by a bolt. In Figure 6 the range of
motion (ROM) of DUALarm is described: maximum and minimum angular ranges of the
link are reported along with the distance between a
and a axes and maximum and minimum distance between
the handle and a axis.
Figure 6.
Schematic representation of DUALarm range of motion. In the picture
the maximum and minimum angles of link rotation together with the
more internal and more external positions of the handle along the
link are presented.
Schematic representation of DUALarm range of motion. In the picture
the maximum and minimum angles of link rotation together with the
more internal and more external positions of the handle along the
link are presented.A complete description of the kinematic model of the device is presented in
Appendix 1.
Manufacturing
The device was manufactured thanks to the fused deposition modeling (FDM)
technology, an additive manufacturing process consisting in laying tracks of
molten thermoplastic polymer onto a platform to obtain a layer of material on
the XY plane of the machine (3D-printer). Once the molten layer has solidified,
other subsequent layers are deposited in a bottom to top manner, in order to
create the complete 3D object in the Z direction of the machine.All the 3D-printed parts of the device were made by the low-cost FDM 3D-printer
Sharebot NG, a machine built following the RepRap layout and, for this reason,
very similar for technology, building volume and performances to the wide
majority of the low-cost desktop 3D printers commonly found in research labs and
FabLabs. The plastic used to build the entire prototype was PLA with a wire
diameter of 1.75 mm. Custom parameters for the aforementioned printer have been
created and main parameters used are the following: three layers of bottom,
three layers of top, 0.2 mm of layer height, four perimeters, 30% “grid” infill
percentage, / raster orientation for bottom and top solid layers (Figure 7). These
parameters were used to guarantee a suitable mechanical resistance in order to
test the first prototype in several conditions, from normal to heavy use, and to
ensure the presence of enough material, especially around holes, to perform
subsequent operations, like boring or countersinking, to remove potential
imperfections coming from the 3D-printing process.
Figure 7.
DUALarm manufacturing session with the Sharebot NG FDM 3D-printer.
The four PLA perimeters and the 30% “grid” infill percentage are
visible.
DUALarm manufacturing session with the Sharebot NG FDM 3D-printer.
The four PLA perimeters and the 30% “grid” infill percentage are
visible.Even if carefully chosen, some 3D-printing parameters like raster angle, raster
width, thickness of layers or air gaps between tracks affect mechanical
properties of printed parts.[34,35] The bottom-to-top layer
structure of the FDM printed components causes the resulting product to be
anisotropic for several reasons. Due to this condition, the most common cause of
everyday-life mechanical failure for FDM components is delamination between
layers originally deposited in the Z direction of the 3D-printer.[34] One of the best ways to avoid delamination between layers is to do a
correct design and manufacturing planning, in order to produce a component which
will not be stressed in the delamination direction. This approach has been used
for almost all the parts of the DUALarm device. Where this condition was not
possible, mechanical locks or couplings have been placed, in order to reduce the
stress affecting the component on the manufacturing Z direction. As previously
stated, all the parts DUALarm is made of are realized in PLA, an easy to print
but also very vulnerable to ageing polymer. Different materials with better
mechanical properties will be tested in the future inside the DUALarm
manufacturing process. Among these higher performance materials ABS, nylon, and
carbon reinforced polymers could be tested in order to find a better candidate
resulting in more rigid, more durable, and longer-lasting parts.In order to avoid the typical high friction between two PLA 3D-printed parts,
polypropylene components (1.5 mm in height) were positioned onto critical
surfaces like the area between upper link (left and right) and upper support
plate (left and right), lower link (left and right) and lower support plate
(left and right), gears and support plates, handle (left and right) and
upper/lower links (left and right). These parts were produced by cutting a sheet
of polypropylene obtained by a lamination process, technology which ensures the
higher level of smoothness for this kind of material.
Mechanical tests
In order to estimate physical characteristics related to the 3D-printed mechanism
of the device, a set of different measuring experiments was done. An
experimental setup shown in Figure 8 was laid-out to acquire both data about the static friction
and the backlash inside the device.
Figure 8.
DUALarm mechanical test bench: a pulley,
b adjustable tripod, c load
plate, d Dyneema rod, e Optodyne
LDS-1000 laser emitter, f Optodyne LDS-1000
acquisition system, g Optodyne LDS-1000 mirror with
clamping tool, h DUALarm clamp.
DUALarm mechanical test bench: a pulley,
b adjustable tripod, c load
plate, d Dyneema rod, e OptodyneLDS-1000 laser emitter, f OptodyneLDS-1000
acquisition system, g OptodyneLDS-1000 mirror with
clamping tool, h DUALarm clamp.
Experimental setup
Here is the setup for both the experiments: DUALarm was secured onto a rigid
structure by two clamps. A crushproof Dyneema wire (1 mm in diameter) was
secured around the right handle of the device and both the ends of the cable
were respectively connected to load plates. The perpendicularity between the
wire and the right link of the device was maintained by a system of two
adjustable tripods and two pulleys (one for the front side and one for the
back side of the device). A OptodyneLDS-1000 contactless acquisition
system, made by a laser emitter and a mirror, was used inside the setup. The
LDS-1000 mirror was secured onto the lower right link of the DUALarm and the
laser emitter was placed in front of it with the axis of the laser beam
parallel to the axis of the Dyneema wire.
Static friction
In order to determine the static friction inside the system, the front load
plate was loaded as long as the right handle did not move significantly. A
significant movement of the link was registered in regard to a force of
5.2 N. Being the distance between the axis of revolution
a and the axis where the force was
applied (axis of the right handle) 125 mm and the applied force 5.2 N, the
resulting static friction torque is 0.65 Nm.
Mechanical backlash
In order to determine the mechanical backlash of the device, several series
of complete loading-downloading cycles were done in regard to the front and
the back load plates in the same experimental layout previously described.
All the measurements were made by the OptodyneLDS-1000 contactless
acquisition system and the resulting sets of data were used to extrapolate
the force/displacement characteristic presented in Figure 9. The mechanical backlash of
the device when g engages
g is visible along the Y axis and is
equal to 0.87 mm for the handle positioned at 125 mm from the
a axis.
Figure 9.
DUALarm force/displacement characteristic when
g engages
g. The highlighted segment
on the Y axis corresponds to the 0.87 mm backlash of the system
in the aforementioned configuration.
DUALarm force/displacement characteristic when
g engages
g. The highlighted segment
on the Y axis corresponds to the 0.87 mm backlash of the system
in the aforementioned configuration.
Electronics and software
Even though DUALarm is a completely mechanical device and does not require any
additional mechatronical component to perform its rehabilitative tasks, it is
equipped with some basic electronical components in order to monitor the
activity of patients during rehabilitation sessions.Two potentiometers () are in charge of measuring and recording the angular rotation
of the DUALarm’s links and, therefore, of estimating the patient’s limbs
positions. The data acquisition system is implemented in a Arduino
UNO microcontroller, acquiring the angular position of each of the
two handles in real time. Thanks to this acquisition system it is possible to
convert the analog signal coming from the potentiometers to a digital signal
that can be transmitted through a serial connection to a common PC.The high-level PC program is implemented in Python, an easily customizable,
open-source and cross-platform language, allowing the program to run on
different operating system, even on Linux-based open-source and free
distributions, contributing to lower overall use costs of the device. As
depicted in Figure 10
the graphical user interface (GUI) of the device is mainly divided into four
parts. The first comprises buttons for the initialization of the device, the
calibration of angular measures, and a simple editor useful for tridimensional
environmental programming. Thanks to this editor the required ROM can be
displayed in the second portion of the GUI thanks to an interactive pie chart.
Additionally, the colors of the pie chart are related to the ratio between the
desired speed for the exercise and the speed achieved by the patient. Finally,
the third portion is useful to visually display a real-time updated log of
measured angular positions and actual positions of the handles, while the fourth
displays the same values in a textual mode. Through customized python scripts it
is possible to program exercises, showing to the patient different target points
to be reached, tuning the required ROM and target distances according to the
actual capabilities of the patient. Reaching time, errors, and other parameters
can be constantly logged to have a comprehensive measurement of the exercise.
Figure 10.
DUALarm graphic user interface. From left to right: (1) text box to
program script-based rehabilitation exercises; (2) tridimensional
feedback for the user; (3) real-time graphs; (4) current
parameters.
DUALarm graphic user interface. From left to right: (1) text box to
program script-based rehabilitation exercises; (2) tridimensional
feedback for the user; (3) real-time graphs; (4) current
parameters.
Experimental trials
A preliminary experimental campaign on healthy subjects (Figure 11) was performed. As main general
objective, the trials were conceived to investigate physiological interaction with
DUALarm in terms of muscular activation patterns. The specific aims were:
Figure 11.
First experimental trials have been performed with healthy subjects.
defining which representative subset of muscles of both limbs was mainly
involved in the planar reaching movement;defining the timing of activation of the above selected muscle to be used
as reference for the evaluations on neurological patients;distinguishing muscular activations in different interaction modalities
(monolateral, bilateral IP–AP).First experimental trials have been performed with healthy subjects.Furthermore, DUALarm usability on patients is discussed.
Methods
Study design
Each healthy subject performed preliminary monolateral trials with both right
and left limbs, with sEMG recorded on eight muscles (upper trapezius, middle
trapezius, pectoralis major, deltoid anterior, deltoid posterior,
infraspinatus, biceps brachii, and triceps brachii). A visual inspection of
the EMG signals made by an experienced physical therapist allowed the
selection of the four more representative muscles involved in the motor
task: biceps brachii (BIC), infraspinatus (IS), deltoid anterior (DA), and
deltoid posterior (DP). Every subject underwent four different trials, each
consisted of 12 cycles (each cycle was composed of a push forward and a pull
backwards phase), performed in the following modalities:In-phase (IP): both the arms work simultaneously
during the push forward and pull backwards phases.Anti-phase (AP): the two arms worked in
counter-phase.Monolateral (M, right and left): only one arm at
a time was involved in the task.
Participants
Five healthy subjects, mean age 34.8 ± 17.7, 4F, 1M, all right-handed,
participated in the trials.
Equipment
Surface-EMG activity of the four selected muscles (BIC, IS, DA, DP) was
recorded from both arms with the BTS FREEEMG300 system.Kinematics was acquired with the SMART 3D BTS marker-based optoelectronic
system. Eight bony landmarks were recorded: the D5 and C7 vertebra, the
right and left acromial process, the right and left lateral homerus
epicondiles, and the right and left ulnar styloid.[36]
Data analysis
Data were analyzed with in-house developed software. Kinematics was used to
detect movement phases. Only the forward phase was considered for analysis.
In each trial, mean muscular activations (MMA) of each muscle were computed
as follows where n is the number of forward phases and EMG is the EMG envelope.
Results and discussion
During the execution of the tasks, the device could easily withstand the loads
applied by healthy subjects.MMAs during IP, AS, and M trials are reported in Figure 12.
DUALarm healthy muscular activations. (a) Shoulder
intrarotation–extrarotation. (b) Hand (elbow) pronation–supination.
(c) Wrist flexion–extension.DA is the main agonist muscle of the forward phase of the movement, pushing
frontally and supporting the weight of the arm. Therefore, analysis and
discussion are based mainly on DA activity.First results indicate that DA activations are higher in monolateral trials than
in bilateral ones. Furthermore, in-phase trials show higher activations than
anti-phase ones. Activations are symmetrical between the limbs in monolateral
and in-phase trials, while anti-phase trials show higher activity in the
dominant limb.In AP trials, DA of the right and left limb fire during the forward phase of the
corresponding limb, with a clear predominance of the dominant side on DA agonist
action, maybe due to the fact that the dominant limb is usually more specialized
in dynamic more demanding tasks.[37]In IP trials, instead, DA of the right and left limb activate equally, and higher
than in AP trials. This phenomenon is probably explained by the fact that during
AP trials the forward phase of each limb is partially supported by the gravity
force of the limb engaged in the coming back phase that pulls in the direction
of motion.
Usability trials on patients
Some trials were conducted even on four hemiparetic post-strokepatients with
different functional levels to verify whether they were able to use the
system and if the core mechanism of the device was able to adapt to
non-physiological interactions. Data were not systematically recorded, thus
they are not reported. Patients were characterized by different body
function, assessed with the Fugl-Meyer Assessment (maximum score = 66;
P1 = 40, P2 = 15, P3 = 30, P4 = 48) and physical builds (P1 = 186 cm,
119 kg; P2 = 182 cm, 80 kg; P3 = 162 cm, 63 kg; P4 = 165 cm, 70 kg).All patients could perform both monolateral and bilateral sessions.
Qualitatively, patients took advantage of DUALarm bilateral design in terms
of balance, smoothness, and fatigue. Furthermore, the device showed no
mechanical yielding or failure.
Safety and certification
Safety for both the patient and the operator is an essential feature for biomedical
devices, which is why great importance is attached to product certifications.
Three-dimensional printing has given rise to safety and security issues that merit
serious concern.[38] Although 3D printing should not be banned, its safety over the long term will
clearly need to be monitored.[39]Manufacturing applications of 3D printing have been subjected to patent, industrial
design, copyright, and trademark law for decades.[40] However, there is limited experience regarding how these laws should apply to
the use of 3D printing by individuals to manufacture items for personal use,
nonprofit distribution, or commercial sale.[40]Certification itself becomes a field of technical-legal research that should be
adapted to the regulations of each state, but also able to open the doors to a
technology with great potential. To satisfy the need for certification, every step
of the production process must be standardized in terms of quality and composition.
The certification is of great importance to ensure to the end user a standard of
quality and production with a security level proportional to the possible risks
inherent to any device. Three-dimensional printing is an innovation that captures
still unprepared from this point of view. The materials used for printing are well
certified (PLA, ABS, nylon, etc.) but today there is no real certification or
guidelines referred to print method.[34] A number of fairly simple 3D-printed medical devices have received the FDAs
510(k) approval.[41] However, fulfilling more demanding FDA regulatory requirements could be a
hurdle that may impede the availability of 3D-printed medical products on a large
scale.[42,41]Meanwhile, before considering and certifying the device as fully biomedical, a set of
printing parameters are given (sec. manufacturing) and considered unofficially
reliable according to authors’ experience as a good compromise among lightness,
cheapness, and mechanical reliability. Technical and clinical tests will aim at
assessing the proper functioning of DUALarm and await positive outcomes of the
DUALarm-based therapy.
Conclusions
The global impact of the DUALarm project is expected to be relevant, thanks to the
exploitation of open-source hw/sw more and more available and to low-cost production
technologies. This availability is somehow satisfying the continuous and growing
request of effective solutions required by the health sector. Positive outcomes from
a medical point of view can and must be coupled with the humanitarian relapses,
thanks to the possibility of reaching parts of the world in which the use of
effective medical devices is precluded due to unsustainable costs.In order to deeply evaluate the medical effectiveness of the DUALarm-based therapy,
it will be required to perform an extensive experimental campaign in order to
understand the actual neurological recovery benefits. To understand as widely as
possible the use effects of DUALarm a preliminary experimental campaign has recently
started, exploiting the use of professional data acquisition systems to monitor both
kinematics and electromyographic activity of a set of healthy subjects (sec.
experimental trials). Further tests will involve impaired people in order to draw
assessed guidelines for the correct use of the device by patients.As a further study, the DUALarm core mechanism (with pertaining mechanical changes)
could be exploited in other low-cost, open-source and 3D-printable rehabilitation
devices in order to perform other simple although important movements like shoulder
intrarotation–extrarotation, elbow pronation–supination or wrist flexion–extension
(Figure 13).
Figure 13.
Schematic representation of possible bilateral movements (in-phase and
anti-phase) for further studies. In each figure the orientation of the
two rotation axes of the DUALarm mechanism is represented in red and
green.
Schematic representation of possible bilateral movements (in-phase and
anti-phase) for further studies. In each figure the orientation of the
two rotation axes of the DUALarm mechanism is represented in red and
green.From the humanitarian point of view, DUALarm has been developed to be produced and
used both in industrialized and in developing countries. The minimum set of elements
required to realize the device is: an Internet connection, a 3D-printer, a
3D-printing PLA filament and basic electronic components. DUALarm project aims at
having an impact in the health sector without geographical, social, and economic
distinction thanks to its low-cost approach and its exploitation process,
characterized by a web platform dedicated to biomedical projects which will
guarantee the full and wide access to the product and all the related
documentation.
Authors: Albert C Lo; Peter Guarino; Hermano I Krebs; Bruce T Volpe; Christopher T Bever; Pamela W Duncan; Robert J Ringer; Todd H Wagner; Lorie G Richards; Dawn M Bravata; Jodie K Haselkorn; George F Wittenberg; Daniel G Federman; Barbara H Corn; Alysia D Maffucci; Peter Peduzzi Journal: Neurorehabil Neural Repair Date: 2009-06-18 Impact factor: 3.919