Grip strength measurement is one of the most accessible methods for measuring overall muscle strength, and many studies have shown a link between low grip strength and future diseases. In recent years, devices for grip strength measurements that can connect to digital devices for automatic data recording have been developed. However, such devices have high development costs and require daily maintenance. Therefore, this we propose a grip strength measurement method using the capacitance sensor of a smartphone and no electronic parts on the measurement device side.

1. Maintenance-Free
Smart Hand Dynamometer
Sarii Yamamoto
Keio University
Kaori Ikematsu
Yahoo! JAPAN Research
Kunihiro Kato
Tokyo University of Technology
01 Introduction
02 Principle
Grip strength measuring devices and smartphones
- Create grip strength measuring device in which the distance between two plates is varied
by a spring
- Attach the device to smartphone and start measuring
- Detect the distance between two points at the start of measurement
- Detect the two closest points during measurement
- Determine the difference and the grip strength is estimated from the grip strength
estimation model
Muscle strength declines with age
- Affects future risk of falls and fractures
Jammer-type grip strength meter
- Measurement method in the sitting position
Background
Commercial digital grip strength meter require
battery replacement, recharging, and other
maintenance is required
Jammer-type grip strength testers have difficulty
maintaining correct posture during measurement.
Challenges
Estimates grip strength from changes in
smartphone touch coordinates
No electronic devices on the measurement
equipment side for maintenance-free grip
strength measurement
Approach
03 Application
Capacitance Sensor
- Obtains the coordinates of two
points on the smartphone
Acceleration sensor
- Detects smartphone tilt
- When the smartphone is tilted
more than 30°, the screen
changes color and instructs the
user to correct the measurement
05 Results 06 Discussions
- Improve accuracy
- Reduce errors in measurement
- Design
- Seek a shape that is easy to grip and apply force
- Evaluation of posture presentation
- Set tilt tolerance based on medical knowledge
- Detect not only tilt but also movement of the smartphone
during measurement
Contact us: info-lcl-group@keio.jp
Yuta Sugiura
Keio University
04
Grip Strength
Estimation Model
Linear regression equation
𝑦 = 4.2265 × 𝑥
coefficient of determination
𝑅2
= 0.999
Comparison with Jammer-type
grip strength meter
MAPE 32.34%
Reproducibility of the
proposed method
MAPE 19.37%
Fei Gu
Keio University