Introduction: Biomedical engineering is an inherently interdisciplinary field emerging from the integration of engineering, medicine, and biology, with the primary objective of developing tools, devices, and technologies for the diagnosis, treatment, and enhancement of patients’ quality of life. By merging engineering principles such as mechanics, electronics, biomechanics, and software with the practical demands of medicine, it provides a robust platform for fostering innovation in healthcare. Biomedical engineers not only contribute to the design of advanced medical equipment and devices but also, through the analysis of clinical processes and patients’ biological responses, deliver efficient and safe solutions to enhance therapeutic outcomes.
The multidisciplinary nature of this discipline fosters synergy between the creativity of engineers and the critical needs of medicine, thereby securing a distinguished position for biomedical engineering within science, technology, and clinical research. The close collaboration between engineering and medicine ensures that the practical requirements of hospitals and healthcare centers—such as improving patient safety, enhancing the usability of equipment, and increasing staff efficiency—are addressed through engineering innovations. Furthermore, the advancement of modern technologies in this domain, ranging from diagnostic and therapeutic devices to intelligent systems and medical robotics, facilitates the provision of cutting-edge, minimally invasive solutions to human health challenges, thereby further reinforcing the role of biomedical engineering in improving the quality of life for patients [1].
Methods: Engineering for Ergonomics and Safety: A Case Study on the Behina Patient Lift
The selection of raw materials in the design of medical and rehabilitation equipment is one of the key factors in ensuring patient safety, reducing caregiver strain, and increasing product durability. The Behina patient lift, as an example of advanced patient transfer equipment, has been designed based on ergonomic principles and materials engineering. This study introduces the main components of the lift and examines the materials used in each section, along with their mechanical, chemical, and biological properties.
1. Main Frame and Chassis
Material: Low-carbon steel with electrostatic powder coating
Properties:
Medium tensile strength: 370–500 MPa
Surface hardness: 120–180 HB
High impact resistance
Easy to weld and shape
Advantages: Adequate strength to withstand dynamic loads (movement, stopping, transfer) with reasonable cost, ideal for mass production. The electrostatic coating prevents corrosion caused by disinfectants such as sodium hypochlorite.
Scientific reference: A study on hospital equipment demonstrated that powder coatings can double the service life of metal structures [3].
2. Columns and Moving Mechanisms
Material: Lightweight steel
Properties:
Tensile strength up to 500 MPa
Corrosion resistance against moisture and cleaning agents
Advantages: Lightweight columns allow easy handling by nurses and caregivers. Reducing the device’s overall weight is ergonomically important.
3. Seat and Backrest
Material: High-density polyurethane foam with PVC synthetic leather cover
Properties:
Density: 40–50 kg/m³
Shape recovery after compression
Moisture resistance and waterproof
Advantages: Distributes pressure on the pelvis and spine effectively, preventing pressure ulcers. PVC cover allows regular cleaning and disinfection.
Scientific reference: Black et al., 2018 reported that polyurethane foam–based surfaces reduce the incidence of pressure ulcers in hospitalized patients by up to 40%.
4. Footrest
Material: Rigid PVC sheet
Properties:
Tensile strength: ~40–55 MPa
Heat resistance up to 75 °C
Chemical resistance to alcohol and disinfectants
Scientific reference: Identified as a suitable replacement for heavy metals in medical equipment due to its lower weight and higher chemical resistance [4].
5. Wheels
Material: ABS
Properties:
Tensile strength: 40–50 MPa
Smooth, vibration-free movement
High point load capacity
Advantages: Combines impact and abrasion resistance with light weight, facilitating movement and reducing dead load in mobile systems. High moldability enables precise, uniform designs. Chemical resistance ensures durability in diverse environments. Cost efficiency compared to many engineering polymers makes it an economical choice for industrial wheels.
6. Horizontal Column Between Main Frame and Wheels
Material: High-carbon steel
Properties:
Density: ~7.85 g/cm³
Tensile strength: 400–600 MPa (depending on alloy and heat treatment)
Surface hardness: 150–250 HB or higher
Better wear resistance than mild steel
Lower ductility than low-carbon steel
More difficult to weld, especially if high-carbon or alloyed
7. Safety Belts and Accessories
Material: Nylon straps with ABS or metal buckles
Properties:
Nylon tensile strength: up to 75 MPa
Low moisture absorption
High flexibility
Advantages: Durable straps with secure fastenings ensure maximum patient safety during transfer.
Scientific reference: Studies identify nylon straps as the safest option for supportive equipment, with failure rates of less than 0.5% [5].
3‑1 Mechanical Design and Material Selection
The Behina manual patient lift is designed to ensure safe, stable, and ergonomic patient transfers. The device was modeled in CATIA V5, with all components, dimensions, and motion angles designed to comply with human ergonomics standards. Overall dimensions: 80 × 70 × 60 cm, with a load capacity of 130 kg.
Patient platform and arms: Made from HDPE for mechanical strength, disinfection capability, and easy cleaning.
Joints and connectors: Stainless steel (screws, pins, hinges) for corrosion resistance [6].
Modeling and Simulation:
All parts were modeled in CATIA and imported into ANSYS Workbench 2022 R2 for static and stress analysis under a maximum 130 kg load with a 20% safety factor.
Boundary conditions:
Fixed supports at the base
Load applied to the patient platform
Outputs: Stress distribution, strain, and critical points assessed to ensure safety under all operating conditions.
Validation: Results compared with ISO 10535:2011 and peer-reviewed studies [7].
Fabrication Tools and Processes:
Cutting and forming: Laser cutting and sheet metal bending for precise dimensions and angles.
Welding and fastening: MIG/TIG welding for structural joints; stainless steel M10 bolts tightened to 45 N·m for detachable connections.
Finishing: Sanding, polishing, and anti-corrosion coating for durability and surface safety.
Assembly tools: Torque screwdrivers, Allen and socket wrenches, precision calipers.
Assembly and Fastening:
Columns and base: Bolted and welded for maximum stability under load.
Washers and bolts: Equipped with flat and spring washers to prevent loosening and reduce vibration.
Results: Quality Control and Performance Testing:
Prototype tested with a 130 kg mannequin
Tests included:
Vertical motion and lifting/lowering speed
Stability under lateral and longitudinal forces
Measuring instruments:
±500 N load cell for force measurement
±100 mm linear displacement sensors
Results validated against ISO 10535:2021 [7]
Safety and Hygiene
All patient-contact surfaces are smooth, resistant to disinfectants, and free of sharp edges. Design allows rapid cleaning and frequent disinfection, minimizing infection risk in clinical environments.
3‑2 Load Analysis
The main load on the patient lift comes from the patient’s weight. For safety design, each seat is assumed to carry 200 kg, totaling 400 kg:
(1)
P_seat = 200 kg, P_total = 400 kg
The gravitational force is calculated as:
(2) F = m · g
Where:
m: patient mass (kg)
g: acceleration due to gravity
Thus:
(3)
F_seat = 200 × 9.81 ≈ 1962 N
F_total = 400 × 9.81 ≈ 3924 N
These vertical forces act on the platform; beam, arm, and column designs must withstand these loads [7].
3‑3 Cantilever Beam Analysis
The lift arm acts as a cantilever beam fixed at one end and loaded at the other. This model is used for bending stress and deflection analysis [8].
Maximum Moment:
(4) M_max = F × L
Where F is the vertical load (N) and L is the arm length (m).
Bending Stress:
(5) σ_max = (M_max × c) / I
Where c is the distance from the neutral axis to the outer surface, and I is the moment of inertia.
Deflection and Slope:
(6)
δ_tip = (F × L³) / (3 E I)
θ_tip = (F × L²) / (2 E I)
Shear Force:
(7) V_max = F
Maximum shear force occurs at the base joint and must be considered in pin and joint design.
Friction and Lateral Forces:
F_friction = μ × F_wheel
Where μ is the wheel–floor friction coefficient, and F_wheel is the normal load per wheel.
Joint Torques:
(8) M_pin = F × d
Where d is the distance from the pivot point to the load application point [10].
Conclusion: Conclusion
Based on the analyses conducted, it can be asserted that the patient lift is no longer merely a simple auxiliary device, but rather a vital instrument in the modern healthcare system. By enabling safe, rapid, and injury-free transfers, such equipment simultaneously fulfills two fundamental needs: enhancing the quality of life and comfort of patients, and reducing the physical and psychological strain on healthcare personnel. Patient lifts, grounded in ergonomic principles, biomedical engineering, and advanced technologies, can serve as a bridge between safety, efficiency, and human-centered care in clinical practice. Therefore, investment in the development and implementation of these systems should be regarded not as an option, but as a strategic necessity for a safer and more humane future in healthcare.