Bioengineering applies engineering principles to biological systems and living organisms. Includes: medical devices and imaging, biomaterials, tissue engineering, systems/synthetic biology.

1. LECTURE 7 – FALL2025
Biomechanical engineering
Assoc. Prof. Dr. Jasmin Šutković
Date: 27.11.2025
Course: Introduction to Bioengineering

2. Bioengineering: The Big Umbrella
• Bioengineering applies engineering principles to biological
systems and living organisms.
• Includes: medical devices and imaging, biomaterials, tissue
engineering, systems/synthetic biology.
• Biomechanics is one subfield within bioengineering.
• Overall goal: improve health, the environment, and our
understanding of biology.

3. Examples

4. Biomechanical Engineering / Biomechanics
• Biomechanical engineering combines mechanics, biology, and
engineering to study and design for living systems.
• Often treated as a subfield of mechanical and biomedical
engineering.
• Focuses on:
– motion of the body (gait, sports, posture),
– mechanical behaviour of tissues (bone, cartilage, muscle), and
– devices that interact with the body (prostheses, implants).

5. How Biomechanics Fits into Bioengineering?
• Bioengineering: broad – all biological systems (health,
agriculture, environment).
• Biomechanical engineering: subfield focusing on mechanics of
tissues and movement within that medical/biological context.
• These areas interact tightly in device design, rehabilitation,
sports, and healthcare.

6. From Molecules to
the Whole Body
• Molecular/cellular: cytoskeletal
mechanics, cell stiffness, protein
motors.
• Tissue/organ: bone, cartilage, muscle,
tendons, blood vessels.
• Whole body: gait, balance, sports
performance, ergonomics.
• Bioengineering integrates
information from all these scales for
diagnosis and device design.

7. Mechanical Engineering
Concepts in Living Systems
• Statics & dynamics: joint forces and moments in
standing, walking, and lifting.
• Solid mechanics: stress, strain, and Young’s
modulus of bone, tendon, and cartilage.
• Fatigue & failure: fractures, implant loosening,
tendon and ligament tears.
• Fluid mechanics: blood flow in vessels and
airflow in the lungs.
• Control: neuromuscular control of posture and
movement.

8. How We Measure
Human Movement
• 3D motion capture (cameras + markers)
to obtain positions, velocities, and joint
angles.
• Force plates to measure ground reaction
forces and moments.
• Pressure insoles / pedobarography to
measure plantar pressure distribution.
• Electromyography (EMG) to measure
muscle activation patterns.
• Gait laboratories combine these tools for
clinical and research analysis.

9. Modeling & Simulation in Biomechanics
• Finite Element Analysis (FEA) for stress/strain in
bones, joints, and implants.
• Multibody dynamics for motion of linked segments in
gait and sports.
• Computational Fluid Dynamics (CFD) for blood flow
and heart valves.
• Simulations allow testing of virtual designs before
making physical prototypes.

10. Prosthetic Limbs: Mechanics Meets
Medicine
• Biomechanics: compare normal vs.
prosthetic gait (step length, symmetry, joint
loads).
• Biomechanics: evaluate socket pressure
distribution and alignment.
• Bioengineering: choose materials (carbon
fiber, titanium), suspension systems, shock
absorbers.
• Bioengineering: integrate sensors and
microprocessor control in knees and feet.
• Clinical aim: lower energy cost of walking
and improve comfort and safety.

11. Hip & Knee Replacements:
Load and Longevity
• Joint reaction forces can reach several
times body weight during walking.
• Biomechanics: analyze load transfer
through implant and surrounding bone.
• Biomechanics: study stress shielding and
risk of bone resorption.
• Bioengineering: use biocompatible
materials (Ti alloys, Co–Cr, UHMWPE).
• Bioengineering: apply surface coatings for
better osseointegration and reduced wear.
• Goal: longer-lasting implants and
improved patient mobility.

12. Blood Flow, Valves, and Stents
• Hemodynamics: pressure, flow rate, and wall shear
stress in arteries.
• Biomechanical issues: deformation and fatigue of
heart valves and stents.
• Biomechanical issues: risk of aneurysm growth or
plaque rupture.
• Bioengineering: design stents (geometry, materials
such as Nitinol) and mechanical vs bioprosthetic
valves.
• CFD-assisted design helps achieve optimal flow and
reduce complications.

13. Sports Biomechanics and Equipment Design
• Analyze sports technique to enhance performance and
reduce injury risk.
• Measure joint angles, forces, and muscle activity
during key sports movements.
• Bioengineering: design running shoes, helmets,
racquets, and protective gear using biomechanical
data.
• Example: optimizing running shoe cushioning and
stiffness to reduce tibial shock and knee loading.

14. Case Study: From Simulation
to Powered Prosthesis
• Problem: transtibial amputees often have higher
energy cost and joint overloading.
• Biomechanical analysis uses gait data and simulations
to determine required ankle plantarflexion torque and
timing.
• Biomechanical goal: minimize socket pressure and gait
asymmetry.
• Bioengineering design: actuator and transmission
(motor, springs, cables) with sensors for angle and
load.
• Control algorithms provide powered push-off for more
natural ankle motion.
• Result: improved walking speed and comfort compared
with passive prostheses.

15. Rehabilitation Robotics & Assistive Devices
• Biomechanics is used to characterize
pathological gait (stroke, Parkinson’s
disease, cerebral palsy).
• Bioengineering: design robot-assisted
gait trainers, exoskeletons, and smart
walkers.
• Sensors monitor balance, muscle
activity, and risk of falls.
• Goal: restore independent walking,
reduce fall risk, and personalize
therapy for each patient.

16. Wearables, Smart Insoles,
and Everyday Gait Data
• Motion capture labs are accurate but expensive
and limited to controlled environments.
• Wearable sensors (IMUs, EMG, pressure
insoles) extend biomechanics into daily life.
• Real-life example: smart insoles with multiple
pressure sensors and machine learning to
classify motion and detect early health
problems.
• Bioengineering challenges: accurate sensing,
low power consumption, wireless
communication, and user comfort.

17. AI + Biomechanics =
Smarter Bioengineering
• Large datasets from gait labs and
wearables enable data-driven analysis.
• Machine learning is used for gait
classification and detection of
pathologies.
• AI helps with sports performance
analysis and coaching based on
biomechanical data.
• AI-based controllers can adapt
prostheses and exoskeletons in real time.
• Explainable AI is important to make
clinical decisions transparent and
trustworthy.

18. Ethics, Access, and Safety
• Accessibility and cost of advanced prostheses, implants, and
exoskeletons are major concerns.
• Medical devices must satisfy strict regulatory approval and safety
testing.
• Long-term monitoring of device performance and failures is
needed.
• Data privacy is crucial for gait and movement data from wearables.
• Fairness in sports: performance-enhancing prostheses and
equipment raise ethical questions.