A custom force plate for quantifying the force applied by the finger during smartphone usage.

Area of Science:

• Biomechanics
• Ergonomics
• Musculoskeletal Health

Background:

• Increased smartphone use correlates with a rise in thumb-related musculoskeletal disorders.
• Previous research identified varying muscle activation and range of motion during touchscreen interactions.
• A gap exists in readily available devices for precise fingertip force measurement during smartphone use.

Purpose of the Study:

• To design and develop a portable force plate for quantifying fingertip forces during smartphone usage.
• To enable accurate measurement of force magnitude, direction, and location applied by the fingertip.

Main Methods:

• The device incorporates a load-cell structure and foil strain gauges.
• It is engineered for portability to facilitate in-situ measurements.
• Calibration and testing were performed to establish performance metrics.

Main Results:

• The portable force plate demonstrates a force sensitivity of 0.15 N.
• Positional sensitivity was measured at 2.5 mm.
• The device has a maximum measurable force capacity of 3 N.

Conclusions:

• This novel portable force plate allows for the study of hand kinetics and kinematics during smartphone use.
• Applications include developing musculoskeletal and finite-element hand models.
• The device supports ergonomic risk assessment, smartphone interface evaluation, and musculoskeletal injury prevention strategies.