DESIGN AND DEVELOPMENT OF A NOVEL FORCE PLATE

AYMAN SIDDIQUE [ID: 7669311]

MSC MED PROJECT SUPERVISOR: DR. GLEN COOPER

INTRODUCTION: DIABETES AND DIABETES MELLITUSDiabetes Mellitus (Type 2- Diabetes) is a medical condition when the human body is unable to produce the

necessary insulin required, or develops insulin-resistance, i.e. cannot respond to its effects.

In 2013, the IDF had

estimated that the

global expenditure

attributed to the overall

treatment of diabetes

to be about USD 548

billion and USD 678

million in 2013 and

2035, respectively.

PATHWAY TO DIABETIC FOOT ULCERATION

“The lifetime risk of a

person with diabetes

developing a foot ulcer

could be as high as 25%

and it is believed that every

30 seconds a lower limb is

lost somewhere in the world

as a consequence of

diabetes.” –Boulton

As of 2010, 15-20 % of

patients who suffer from

foot ulcers would be in

need of an amputation,

with 85% of these foot

amputations following

diabetic foot ulceration.

ANATOMY OF THE HUMAN FOOT

• 7 short tarsal bones incorporate the heel and back of the instep.

• 5 metatarsal bones constitute the structure for the ball of the foot. Each metatarsal is associated with one

of the toes.

• The toe structure comprises of 14 phalanges and small bones

• Tarsal and metatarsal (MTH) bones provide the arch structure of the foot

• Bands of ligaments inter-connect and constrict the bones

• A thick layer of fatty tissue lies underneath the sole of the foot, in order to absorb the pressure and

shock during various stages of gait

A human foot consists of 26 bones,

which further constitute of 33

joints, 19 muscles, 107 ligaments

and several tendons.

BIOMECHANICS OF PLANTAR FOOT ULCERATION

The skin acts as the medium through which internal forces are conveyed to its surroundings as well as the

environmental external forces that act on the skin itself and its corresponding subcutaneous tissue.

The number of force repetitions

required to cause tissue injury

decreases as the force (pressure)

increases, and vice versa. This is

known as a pressure time

integral, and many researchers

have used this relationship to

determine the risk of

diabetic foot ulceration.

“Mechanical fatigue is defined as the failure of a structure or biological tissue at a

submaximal level to maintain integrity because of repeated bouts of loading.”

Ulceration is instigated due to the combination of reduced sensation (intrinsic factor) and high plantar

pressure (extrinsic mechanical factor) when the foot undergoes uncharacteristic mechanical loading.

PLANTAR SHEAR FORCE MEASUREMENT: A REVIEW

Optical Method (Mackey and Davis, 2006)

Strain Gauge Method (Cheng et al.,2010)

• Force sensor based on strain gauge techniques and

the shear-web principle

• The sensor was able to measure the AP and ML

shear forces and the normal force at the plantar

surface, by utilising the embedded strain gauge

rosettes

• Each strain gauge rosette provided three sensor

output channels

The evaluation of plantar stress distribution is crucial in order to identify diabetic feet that are prone to ulceration.

• Optics-based force sensor which determined pressure and

shear patterns on the plantar surface

• The system is able to measure three-dimensional (3-D) stress

tensors at all points of contact with the sole of the foot.

• The system can be calibrated automatically by simply being

activated, and measures optical phase retardance while

collecting zero-load data

ULTRA-SOUND TISSUE IMAGING: A REVIEW

• Soft Tissue Response Imaging Device (STRIDE)

• Simultaneously subjugated plantar soft tissue to

vertical compression and recorded the

corresponding mechanical response.

• Foot scanner with an embedded tissue ultrasound palpitation

(indentation) system (TUPS) in order to evaluate plantar soft tissue

properties under the loading of different body-weights.

• The scanner allowed real-time tracking of foot movements.

Evaluation of the mechanical properties of plantar soft tissues in conjunction with plantar shear

measurement could facilitate monitoring of diabetes development and subsequent prevention of diabetic

foot ulceration.

TUPS: (Zheng et al, 2010)

STRIDE: (Parker et al.,2015)

PROPOSED DESIGN: AIMS, OBJECTIVES AND SPECIFICATIONS

AIMS:

To design and develop a force plate that can simultaneously measure the

tri-axial shear forces of a specific plantar region, and determine the

mechanical characteristics of its corresponding soft tissue.

OBJECTIVES:

• To design concepts for the force sensor which incorporates strain

gauge techniques and commercial ultrasound devices

• To compare the concepts and progress one of them to the

embodiment design phase

• To validate the embodiment design through use of FEA and

numerical calculations and hence determine a final design for the

force sensor

• To commission and test the final design before proceeding with

manufacturing of force sensor

PROJECT SCHEDULE

PROPOSED DESIGN: DEVELOPMENT, EVALUATION AND FURTHER WORK

Construction and

analysis of FEA

foot model using

MRI images of foot

Integration

into matrix

array

Determination of

sensitivity, hysteresis and

non-linearity

FEA

validation of

force sensor

design

THANK YOU FOR LISTENING

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