1

Biomechanics of Human Body Motion:

Engineering a Glove for Hand Motor Disabilities

Ezra Brooks, Justin Perez, Ilse Sweldens, Annie Wang, Lucy Zhang

Mentor: Catherine Connolly

RTA: Eamon Collins

Abstract

Using SolidWorks, a three-

dimensional engineering design program, a

glove was created to help people with fine

motor skill impairments maintain a desired

hand position. The glove, in order to hold

the hand in the specified position, is rigid,

but it features locking mechanisms on the

finger joints that enable users to adjust it

into whichever hand position is needed.

Poor fine motor abilities are highly prevalent

due to a range of neurological and physical

disorders. The glove was designed to assist

patients in basic hand functions such as

writing; the prototype model is dimensioned

to fit the hand of a child at the age where

writing skills are developing. The glove’s

locking mechanism allows for patients to

achieve easily adjustable hand positions.

SolidWorks was used not only to design the

glove, but also to create an animation of the

assembly of the device, to produce

engineering drawings, and to simulate the

effects of forces on the pieces.

1. Introduction

Hand motility is a crucial aspect of

human function and occupies a significant

portion of the brain’s processes Hands are

capable of touching, grasping, feeling,

manipulating, and more. However, many

people are unable to fully utilize their hands

due to disabilities; 22% of children in

second grade have dysgraphia, the inability

to write properly.1

The following chart depicts the

normal progression of motor skill

development for young children.

Conversely, children with impaired physical

abilities have delayed development.

\

Dysgraphia results from flawed

motor and information processing skills

such as visual-spatial and language

processing. Symptoms include illegible

Figure 1: Development of children including

fine motor2

2

handwriting and awkward pencil grip and

position. Issues with writing and other fine

motor skills can affect people of all ages,

and can result from various conditions.

Dyspraxia is a neurological disorder

throughout the brain that inhibits motor skill

development.3

Autism spectrum disorders

and attention deficit hyperactive disorder

can also lead to motor skill defects.

Parkinson’s disease creates tremors that can

greatly inhibit hand motion.2 Cerebral palsy,

a physical disability that affects movement

and posture, can weaken muscle control,

muscle coordination, and balance.4

From a purely physical perspective,

the primary cause of fine motor control

problems is a lack or overabundance of

muscle mass.5 Children in particular may

have low muscle mass and thus struggle to

maintain control over something as simple

as a pencil or scissors. Genetic and

environmental factors are also causes of

these motor skill impairments. Further,

premature children of substance abusers are

at high risk for this condition. Likewise,

people who have undergone certain types of

surgery frequently have trouble regaining

physical coordination, resulting in difficulty

controlling the fine motor skills of their

hands.

A glove that stabilizes the hands

would mitigate the effects of these disorders,

improving the hand function for people with

impaired fine motor skills. By supporting

the hand with a specially designed glove,

patients should be able to improve hand

motility, rendering activities such as writing

and holding utensils easier. In addition,

wearing the glove for an extended period of

time would allow muscle memory to

develop, so the patient would be able to

instinctively be able to remember the correct

positioning for holding pencils, or utensils.

2. Fine Motor Skills and

Hand Data

2.1 Fine Motor Skills and Children’s

Writing Ability

Fine motor skills affect a person’s

ability to hold, to pick up, or to move

objects. Often, impaired fine motor skills

result in a social stigma, as young children

are unable to perform basic tasks. Problems

related to fine motor skills are common, as

about 20% of children are affected with

dysgraphia, the inability to write correctly,

legibly, or, in some cases, at all.6 These

skills develop slowly as children age, but

can often be overcome with practice.

However, if unaddressed, these problems

may develop into chronic diseases that can

cause many difficulties later in life.

Currently, the side effects of

impaired fine motors skills are difficult to

alleviate. Children who struggle with writing

are given rubber pencil grips and larger

pencils that help students assume the proper

writing position. However, these methods

merely skirt the issue, without addressing

the actual problem, the improvement of fine

motor skills. The children will still struggle

to use normal pencils in the future, as this is

not a permanent fix. For others with

disabilities such as autism or cerebral palsy,

trainers and aides often use a hand-over-

hand7 method in which they guide the

patients hand into forming proper grips and

3

motions to grab and use items. This method

is not entirely effective because the trainer’s

grip is not entirely rigid and it cannot be

used when the trainer is unavailable.

Another attempted solution is the weighted

glove.8 These gloves provide stability and

target fitness, but make basic hand motions

more difficult largely due to the added

weight that requires greater hand strength to

achieve the same functionality as one who

does not use the gloves.

Children are given toys and

worksheets that focus on fine hand

movements, mainly line tracing. These

methods focus on training, but do not give

the basic structure or technique necessary to

easily learn fine motor skills. Therapeutic

weighted gloves contain weights on the top

of the hand. However, these weights must be

adjusted when the hand position is changed,

resulting in both inconvenience and

potential pain.

The other problem is the lack of

proper writing technique. Most people do

not hold the pencil in the optimal position

for writing efficiently and clearly. The

pencil is supposed to be held between the

thumb and index fingers alone. 7

Further, the

pencil should be moved through the use of

shoulder, back, and forearm muscles, as

opposed to the fingers. This problem is

caused by the lack of good instruction of

writing techniques as well as the lack of a

good guide for how to hold a pencil.

2.2 Conditions Related to Poor Fine

Motor Skills

Many diseases that impede motor

development are neurological. For example,

dysgraphia often overlaps with other

learning disabilities such as cerebral palsy

and autism. Brain surgery also creates side

effects that affect motility. To prepare for

surgical procedures, surgeons often use

anesthesia, which generally alters pain

perception, aids muscle relaxation, and

induces a state of unconscious throughout

the body. Motor skills can be temporarily

impaired after anesthesia.10

Similar side

effects are also common after cancer

treatment such as chemotherapy.

Cerebral palsy is also a consequence

of damage to parts of the brain that manage

motor movement, rendering the brain

incapable of sending the appropriate signal

to muscles to make them move properly.

The specific damaged sections of the brain

determine the type of cerebral palsy that the

individual develops. Severely afflicted

individuals may have uncontrollable hand

motions.

For diseases that do not affect the

nervous system, muscle memory provides a

physical method that can make the effects of

temporary solutions permanent. Muscle

memory is stored in the brain as a form of

Figure 2: A weighted glove9

4

procedural memory that improves ability

through repetition. Muscle fibers maintain a

long lasting structural change.

2.3 Anthropometric Data

Anthropometric data describes

average human body measurements and

proportions for a population. In this study

anthropometric hand data was utilized to

ensure that the glove would fit the average

child in need of fine motor skill aid. The

standard deviation of the measurements is

also included in Appendix A, and its small

values show that the glove would fit the vast

majority of children in need.

2.4 Joints Responsible for Writing

Position

The primary joints that determine the

hand’s position while writing consist of the

carpometacarpal, metacarpophalangeal

(MCP as shown in the yellow arrow), and

proximal interphalangeal (PIP as shown by

the blue arrow) joints. The hand joints,

wrist, and bone account for the body's

support and flexibility to manipulate objects,

rendering the stability of the joints as

imperative.

Figure 3: Hand Skeletal Structure11

Figure 4: Joints in the hand12

Figure 5: Primary hand muscles13

5

3. The Design Process:

Brainstorming, Drawing,

and Modeling the Glove

3.1 Experimental Procedure

In determining what biological

disorder to target, general ideas were

discussed based on common diseases as well

as personal experiences. An article on a

possible alternative to using drugs provided

an example of a product that started as an

ambitious idea and is still in the research and

developmental processes. However, one of

the main hindrances to the brainstorming

process was the lack of technical and

scientific knowledge, eliminating many

possible ideas such as miniaturizing

monitors and dialysis machines to fit inside

the body.

Once the glove idea was chosen, it

had to be designed in more detail and drawn

on graph paper with dimensions. The first

step taken was to determine the target

audience of the glove, which was deemed to

be people with fine motor skills

impairments. The glove focuses on the

physical and mechanical aspects only, using

a rigid yet dynamic adjustable brace to lock

the fingers into specified positions. It was

decided that the prototype glove would help

young children with basic functions such as

writing and holding utensils since these

essential skills should, ideally, be learned

and addressed at a younger age. The glove

would also ultimately allow for more

independence and confidence for patients

with fine motor skill disabilities as well as

provide enough support so that patients may

be able to use muscle memory to correct

their positions.

Next, ideas were developed for the

glove’s locking mechanism and structure,

the most important components of the glove.

Both the functionality of the glove and the

appeal to the possible customers were

considered in the design. A completely rigid

glove with fixed fingers was considered at

one point, but it would mean that the glove

could only be used to help patients with one

problem. In addition, it would be difficult

for people to fit their hands into a glove

already in the proper writing position. For

the locking mechanism, the first general idea

was to allow movement for all the joints. A

couple of ideas were considered, many taken

from moving joint parts on knee braces, but

they were all variations of the same basic

mechanism: a locking mechanism that kept

the fingers in a position through interlocking

gears placed at finger joints.

A rigid yet flexible structure was

ideal for the glove frame because it would

keep the hand in place but still allow for

some mobility of the joints and fingers to

avoid cramping and general discomfort.

Modeling the plastic pieces after the bone

structure of the hand was done because it

would be more helpful as a guiding device

as it would simulate an actual human hand.

The attempt to use a type of hard plastic as

opposed to rigid metal aimed to make the

glove more lightweight. A problem that was

later addressed was the movement of the

Figure 6: The initial hand-drawn sketch

6

thumb, which usually requires more

mobility and dexterity than the other fingers

do. It was debated whether or not a piece

specific to the thumb should be designed to

allow for maximum rotational and mobile

functionalities, but it was challenging to

incorporate all the additional parts into the

design considering the added weight as well

as placement and design possibilities.

However, because the positioning of the

thumb is similar when writing and eating, it

was decided that the thumb’s PIP would be

kept entirely rigid with a solid plastic ring.

Although the glove was intended to

target children and patients of all ages, the

prototype was chosen to be modeled for a

seven to eight year old child, mostly for

convenience for 3D printing. Hand

anthropometric data for children aged 7.5-

8.5 from a study in Britain was used to

devise finger measurements for modeling, as

shown in the charts Table 1 in Appendix A.

Because the anthropometric data only

included measurements for the first three

fingers and the lengths and diameters of

those, there was a lack of data on the ring

finger and pinkie and distance between

finger joints. As a result, detailed

measurements were taken of each group

member’s hands, and the ratios of the

lengths of distances between joints were

calculated and averaged to compensate for

the lack of researched data. According to

the data chart in Appendix A, Part 1 refers to

the length of the hand starting at the wrist

and ending at the knuckles. Part 2 of each

finger refers to the distance between the

knuckle and the middle joint. Part 3 is the

distance between the middle joint and the

last joint, where the glove will end in a

velcro-adjustable strap.

As the brainstorming progressed, the

basic functions of SolidWorks were learned

in preparation for the modeling of the glove

design later on. Two-dimensional functions,

such as sketching shapes, creating

dimensions, and assigning constraints, were

essential for defining and constructing the

various shapes necessary for the glove

design. The four major 3D features,

extrusion, loft, revolve, and sweep, could be

manipulated to create the three-dimensional

figures from the 2D sketches. After these

skills were mastered, the assembly feature

was learned. The gearbox that was created

had parts that were fully constrained along

with parts that were intentionally partially

defined to allow for motion. The assembly

feature allows for the different parts, made

separately for precision and efficiency, to be

attached to each other to construct a

complete model.

After discussion of the locking

mechanism, thumb mechanism, and

dimensions with the project mentor,

modeling the device on SolidWorks began.

At the beginning, everyone experimented

with creating new parts on SolidWorks to

test the easiest and best ways to construct

the different parts including the locking

gears as well as the thumb and wrist pieces.

Once the more complicated pieces were

created, the remaining tasks were split

among the group members due to the limited

time available and the amount of work left.

Some group members continued to work to

refine and complete the existing parts while

others created rudimentary models and

worked on the engineering drawings,

7

analysis reports, and animation of the 3D

model in SolidWorks.

3.2 Physical Description of the

Device

The glove has a fingerless fabric

piece covered by rigid plastic supports. The

plastic used is ABSplus-P43014

, a

production-grade thermoplastic used with

Dimension 3D Printers.

The supports begin at a plastic wrist

brace and follow the skeletal structure of the

hand, with one support for finger including

the thumb. The supports ends anterior to the

distal interphalangeal joint, leaving the

fingertips free for comfort and grip. They

end in a slit for a Velcro band to wrap

around the finger. At the two joints, the

metacarpophalangeal and proximal

interphalangeal joints, there is a gear shell

that allows rotation of the finger joint, but

can provide rigidity at any angle of rotation.

For the most effective application,

the gloves are adaptable to different hand

conformations, but are rigid in the selected

one to provide the support and structure

necessary for improving fine motor skills. In

order to achieve this, the gloves have small

gear knobs above the joints, which are

shown in Appendix B.

Within these knobs, two interlocking

gears are layered next to each other

vertically. These gears are rigid, but have

inward teeth that allow interlocking. For the

easiest modeling, these gears are 20-sided

polygons. The left gear (assuming a right

hand glove) has a central hole for a push

button. This gear also has a circular ridge

extrusion at its base that sits on an inverse

ridge in the shell. The hole is filled with a

cylinder connected to the right gear. This

gear sits on a small spring. As the digit is

moved, the right gear rotates, clicking into

place, maintaining rigidity. In order to

unlock the gears, the cylinder button is

pushed in so the two gears’ teeth unlock

allowing rotation back to normal hand

position. The cylinder button must be

pushed in to rotate the joint in either

direction because the teeth are not sloped,

ensuring full rigidity in any position. This

mechanism sits slightly anterior to the top of

the knuckle.

Figure 7: A 3D Model of the glove

Figure 8: Index finger brace 1.

8

The shell mechanism is a basic

hollow cylinder with a hole for the button at

one end and a rigid base with an extruded

circle for the spring to sit in at the other end.

The shell has two slits in it that allow the

finger plastic pieces to connect to their gears

by a thin connector piece. The slit on the

left of the right hand is fitted to the small

plastic connector, whereas the slit on the

right extends down on the opposite side

around 180˚ to allow for the joint to rotate

with the bottom gear. The mechanism has a

length of 7.5mm and a diameter of 5mm.

However, the thumb requires a

different approach. The distal phalanx of the

thumb has an extremely minimal range of

motion. Conversely, the remainder of the

thumb is capable of a wider range motion,

powered by several strong muscles,

including the abductor pollicis brevis, the

abductor pollicis, the first dorsal

interosseous, the flexor pollicis brevis, and

the opponens pollicis.15

To enable the thumb

to adjust positions while still maintaining

rigidity, a similar locking mechanism to the

one described before is attached to the hard

plastic structure around the wrist, right

above the carpometacarpal joint. The

original mechanism is simply rotated onto

its side with the button facing upward, and

the shell is mounted on the wrist brace.

Furthermore, a hard piece of plastic is

attached from above the extrinsic thumb

muscle to above the intrinsic thumb

muscles, restricting the thumb’s motion.

This piece of plastic follows the thumb’s

straight conformation to before the nailbed

ensuring full thumb rigidity.

Designing the glove structure on

SolidWorks required slight revision of the

original sketch. The actual skeletal structure

that functions similar to braces was created

such that the bottom portion has a rounded

surface while the top surface is flat, as to

simplify the addition of the locking

mechanism on top. The gears in the locking

mechanism have differing teeth, trapezoidal

teeth on the gear closest to the cylinder and

the rectangular teeth on the mobile gear. The

differing types of teeth allow for the two

gears to interlock precisely in the assembly

function of SolidWorks. The shell in which

the locking mechanism is contained required

little alterations. The slits which allow for

the plastic material to enter the shell and

attach to the locking mechanism are also of

differing lengths, one that allows for

extensive range of finger motion and one

simply to keep rigidity. The longer slit

Figure 9: Shell

Figure 10: Wrist and thumb brace

9

permits the finger to bend a minimum of 90

degrees.

In order to ensure a certain degree of

mobility and stability for the wrist, there is a

rigid plastic brace over the top of the wrist

that connects to all of the fingers. However,

this brace is secured to the wrist using

Velcro allowing adjustability and rigidity.

The brace only covers the top half of the

wrist. This is placed a little forward of the

wrist joint to allow wrist motion, but still

provide hand rigidity.

At the end of the glove at each

finger, there is an adjustable strap with

Velcro to allow for patients to change the

straps for comfort according to their finger

width. The strap is sewn to the rest of the

glove, with a plastic buckle in the middle. A

flap of the strip with Velcro on it goes

through one side of the buckle so that the

patient can adjust how much of the strap

goes through the buckle and therefore how

tight the strap will be. The portion of the

strap that goes through the buckle comes

into contact with the Velcro piece on the

part of the strap sewn onto the rest of the

glove.

3.3 Dimensions and Descriptions:

The fingers are composed of three

main structural parts: two springs, four

gears, and two shells. Each structural part is

curved to a radius of 9.5mm to match the

curve of the fingers, as well as filleted along

the top to a distance of 3mm to prevent

sharp edges. Each part has a width of

10mm, but the pinky finger uses a 9mm

wide part. The dimensions of the structural

parts along the backs of the hands between

the wrist and the MCP are 45.72mm on the

pinky, 51.38mm on the ring finger, 52.83 on

the middle finger, and 58.10mm on the

index finger. The lengths of the parts

between the next two joints, the MCP and

the PIP, are 26.25 on the pinky 28.67 on the

ring finger, 32.14mm on the middle finger,

and 28.48mm on the index finger. Lastly,

the lengths of the supports after the PIP

before the DIP are 12.62mm on the pinky,

18.43mm on the ring finger, 21.50mm on

the middle finger, and 17.12mm on the

index finger.

The thumb has one structural part,

one spring, two gears, and one shell. The

thumb’s shell, unlike the fingers’ shells, is

positioned with its button facing up from the

back of the palm. The side of the structural

Figure 11: Wrist component

Figure 12: Velcro strap model

10

part that touches the skin is curved with a

radius of 9.50mm, and the other side of this

part has a 3mm fillet. The part is 69.85mm

long and 10.0mm wide, including the gears

and the attachments. The thumb piece ends

in a ring, unlike the others which end in

Velcro straps, to ensure maximum rigidity.

The ring has a diameter of 17mm and is

1mm wide.

Located between the supports on the

fingers are the shells containing the gears

and springs.

The shell is a cylinder with a length

of 7.5mm and diameter of 5mm. The shell

is 0.65mm thick, but has a ridge for the gear

to fit into at one end that is only 0.25mm

thick. 0.70mm from this side of the shell is

located a 0.25mm slit that extends 180

degrees. 2.3mm from this side is another slit

1.75mm in width that extends 180°. This

slit is directly opposite from the original slit.

These slits allow the gears to connect to the

finger supports and for the gears to rotate the

finger pieces. The wider slit allows for the

gear to remain connected to the finger

support as the cylinder button is pushed in.

Within this shell are the two gears.

The gears have a diameter of 4.25mm. Both

gears are 20-sided polygons with each side

being 0.592mm in length, designed to

facilitate interlocking. The gear with the

cylindrical button in the center uses

rectangular gear teeth, which fit together

with the gear with the hole in its center’s

trapezoidal teeth. The gear with a 2mm hole

in its center also has a ridge along its bottom

plane that extrudes 0.50mm. This ridge is to

keep the gear from shifting while in use as it

sits on the shell’s inverse ridge. There are

10 teeth on both gears, and the trapezoidal

teeth extend inward at 72 degrees for

0.50mm. The rectangular tooth gear has

0.45mm by 0.50 mm rectangles, with the

.450mm being along the gear edge, allowing

a small amount of room for the gears to be

easier to interlock. This gear’s cylinder

button is 2mm in diameter and extends out

4.50mm. The gear with the trapezoidal teeth

also has a circular cut on its back that is

2mm in diameter and 0.750 mm deep. This

cut houses the spring. The spring extends

between the shell base and this circle cut.

The spring is 2mm in diameter, 0.25mm in

thickness, and has 7.5 revolutions.

Figure 13: The spring.

Figure 14: The cylinder-button gear

11

4. Results and Discussion

The end product functions as a

therapeutic glove with a skeletal structure

that stabilizes hand mobility and position,

facilitating typical hand movements for

patients with fine motor skill impairments.

The locking mechanism, which contains two

mobile and interlocking gears, allows for

movement of the joints as well as the

function to lock the fingers in a defined,

rigid position. In addition, each

mechanism’s movement is constrained to a 0

to 70 degree range of movement to permit

controlled hand motion.

Finite Element Analysis (FEA) was

also conducted on SolidWorks, using the

Simulation feature. The purpose of the FEA

is to identify the effects of various forces on

the glove’s pieces. The first step taken was

to draw out the hand and identify the

different forces, such as stress, rotational,

and torque, thought to be experienced by

both the hand and the mechanisms attached

to it. The simulations were performed with

the structural piece between the index finger

and the wrist. In the first simulation, the face

touching the wrist piece was considered a

fixed plane, and 1 N was applied to the sides

of the gear’s teeth at the other end of the

piece. This simulated when the finger

attempts to bend while the button is not

pressed and the gears are locked. In the

second, the fixed plane was the same, but

the force was a 1 N pull on the gear, making

the piece experience tension. This replicated

how the pieces are stretched when fingers

bend. Instead of the ABSplus-P430 material

used in the printing of the device, the

simulation modeled the device with the

features of standard ABS plastic. The

ABSplus-P430 plastic has a Young’s

modulus of 2320 mPa, and the simulation’s

ABS has a similar Young’s modulus, at

2000 mPa. The simulation created strain and

stress plots for the piece and revealed that

the section that undergoes the most stress

and strain is the connection between the

main structural piece and the gear. This

section is the one that is most at risk of

breaking.

Figure 15: Shell assembly

12

Figure 18: Strain plot of the first index finger piece

in isometric view

Afterwards, the forces were applied to the

parts in SolidWorks and analysis reports

were generated. The locking mechanism and

the brace attachments were tested for stress

and strain. When bent, the attachments are

stretched slightly by tensile force. When the

brace on the finger returns to a straight

position, it experiences compressive forces.

These situations were simulated using forces

first pulling then pushing each end of the

brace piece. The locking mechanism was

specifically analyzed for the torque which is

exerted when the brace attachments rotate

via the gear. In addition, force was applied

to the center of the brace to test how the

piece would handle collisions when the

glove is in use. The simulation provided

information on the stress and displacement

of the piece in the various scenarios.

In SolidWorks, items with miniscule

dimensions such as the small locking

mechanism components can be easily drawn

and assembled together. However, these

items are not so easily translated into the

physical world. The initial plan to 3D print

the parts did not work out as intended

because the pieces were too small. The gears

failed to interlock as they did in SolidWorks

due to the 3D printer’s lack of precision and

tolerances to properly print items as small as

the parts involved in the finger locking

mechanism. In the commercial world, there

are printers that can print these parts with

accuracy, but these printers are much more

expensive and slower than the ones available

to this research project. In the initial

printing, the STL files had to be scaled to

two times the parts’ original sizes in order to

be printed using the available machine. As it

stands, the gloves will take too long to print,

cost too much, and have too much error if

produced through traditional 3D printing.

5. Conclusion

A glove to aid in fine motor skill

treatment and improvement was created in

SolidWorks, a three-dimensional computer

aided design software. The glove utilizes an

interlocking gear mechanism to provide

rigidity to different finger joints. The rigid

Figures 16 and 17: Stress plot of the first index finger

piece in isometric view

von Mises (Nm

2)

- 166,608,720

- 124,956,552

- 83,304,384 - 41,652,212

- 39.2

von Mises (Nm

2)

- 166,608,720 - 124,956,552

- 83,304,384

- 41,652,212 - 39.2

13

parts are placed upon the back of the hand,

and follow the basic bone structure to allow

limited joint motion. The gears are covered

by a shell but directly connected to a rigid

finger part, providing the needed protection

and practicality. One gear is spring mounted

to allow for repeated locking and unlocking.

The glove provides the support and correct

hand conformations needed to aid in

completing many tasks that require fine

motor skills, such as eating and writing. The

glove ends in adjustable Velcro straps before

the distal interphalangeal joint, allowing for

good finger contact and therefore grip. It is

secured onto the hand using straps from the

fingers and the wrist.

The glove is limited by the gear

teeth, as there are only ten, which may

slightly restrict possible hand

conformations. The glove is similarly

compromised by the tiny connections

between the gear and the finger piece.

Although the FEA results show that the joint

can handle strain, the connection is still

miniscule and runs the risk of breaking

under additional pressure. Furthermore, the

locking system allows locking of different

fingers at different times, which gives more

control and versatility for position, but

requires that each gear be locked

individually, which may hinder quick

conformational changes. The size of the

locking mechanism may also prove difficult

for patients with fine motor skills to use, as

they may require the assistance of an aide.

Lastly, due to the overall glove and shells’

small dimensions as well as limited

available of affordable high quality 3D

printing technology, the glove could not be

printed to scale. If the glove were to

become an actual product, more precise 3D

printers would be necessary to mass produce

the glove, especially since the glove would

ideally be available in different sizes to fit

patients with hands of all sizes.

Thus, future designs should look into

better locking mechanisms that make the

glove more efficient. Additionally, studies

should be done on the effect of this glove on

children learning to write as well as people

with fine motor skill problems. These

studies will prove the effectiveness of the

design.

Acknowledgements

The authors are grateful to Rutgers

undergraduate student Catherine Connolly

for her instruction on the use of SolidWorks

and the development of biomedical devices,

as well as Eamon Collins for his guidance

throughout the project. In addition, this

research would not be possible without the

direction of Ilene Rosen, Dr. Noshir

Langrana, and Dean Jean Patrick Antoine

and the sponsorship of Rutgers University,

The State of New Jersey, Morgan Stanley,

Lockheed Martin, Silver Line Windows,

South Jersey Industries, Inc., The Provident

Bank Foundation, and Novo Nordisk.

14

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Appendix A

Table 1: Hand Anthropometric Data

Table 2: Collected Hand Data from Group Members

17

Appendix B

Figure 19: Diagram of index finger brace 1.

Depicted above is the brace with the structure in which the locking mechanism is attached. The long brace is found

on the PIP; the attached gear is found on the first joint. The stationary gear is linked to a mobile gear that allows for

finger position adjustment before locking it in place.

Figure 20: Gear with push button.

The above gear includes the push button in which the wearer can lock or unlock the brace to position his or her

hand.

18

Figure 21: Shell cylinder body which contains the interlocking gears.

The two interlocking gears are contained inside a shell, designed such that there are slits to allow attachment of the

brace to the gears.

Figure 22: The spring.

Additionally, a spring is attached in the locking mechanism, within the shell, between the gear with the push button

and the wall of the cylinder body. This spring facilitates the actual alteration of finger position when using the

locking mechanism. The elastic energy prevents to the second gear from falling away from its counterpart gear and

thus losing stability.

19

Figure 23: An assembled finger part.

The above is a depiction of a single part of the finger assembly that lies on the thumb. This assembly includes the

two interlocking gears, the push button, the outer shell and shell lids, and finger support brace. On the right of the

drawing are two isometric views of the part, one including a view of the inner gears and one simply depicting the

outside of the mechanism.

Figure 24: Finger velcro that attaches brace to finger.

This piece of velcro extends from small slits in the brace around the finger, keeping the finger and brace firmly

attached to each other to prevent sliding.

20

Figure 25: The whole finger brace, including locking mechanisms.

This piece fits on the ring finger. The velcro straps are not shown.

21

Appendix C

Figure 26: Stress plot of the first index finger piece. In the center is the connection between the main structural part

and the gear. It endures the most stress of the piece. The spectrum goes to 166,608,720 at the red end to 39.2 at the

blue end. The units are Newton meters squared.

22

Figure 27: Stress plot of the first index finger piece. This is during the first test when 1 Newton of force is applied

to the sides of the gear teeth.

Figure 28: Strain plot of the first index finger piece. This is during the first test when 1 Newton of force is applied

to the sides of the gear teeth. The spectrum goes from7.742e-002 at the red end to 1.824e-008 at the blue end.

23

.

Figure 29: Strain plot of the first index finger piece. This is during the second test, when 1 Newton of force is

applied to the side of the gear. The spectrum goes from 5.184e-002 at the red end to 1.933-008 at the blue end.

Figure 30: Displacement plot of the first index finger piece during the second test. The spectrum goes from 1.528e-

000 at the red end to 1.00e-030 at the blue end. The units are millimeters.

Displacement (mm) 1.528e-000

1.146e-000

7.641e-000

3.8203-001

1.000e-030

von Mises (Nm2)

- 111,561,032 - 83,670,784 - 55,780,536 - 27,890,290 - 41.6