A New Instrument to Measure Individual Finger Strength in Palmar Grip

Functional assessment of the upper limbs is the most effective method to verify the motor condition. However, not all dynamometers are sensitive enough to measure individual finger contribution to the force. This paper focuses on a novel virtual instrumentation developed to measure palm grip strength. The instrument was designed with 'ring' shaped parts to optimize interaction with the user's fingers, making it possible to measure the strength of each finger during palm grip. A mobile application developed on the Android system with Google's Flutter framework and Bluetooth connectivity eliminates the need for wires. The application allows the user to choose which hand to be evaluated, adjusts the exercise duration, and includes the user's name. The instrument calibration resulted in errors of 2.737%, 3.614%, 3.452%, 2.520%, 3.804%, and 1.646% for the Right Index, Right Middle, Right Ring, Right Little, Right Thumb, and Left Thumb sensors, respectively. The Experimental Protocol revealed a difference in strength between dominant and contralateral hands of 7.5% for the group considering four fingers (without thumb) and 7.1% for the group considering all five fingers. This study emphasizes the effectiveness of the dynamometer and its application as a valuable tool in the accurate assessment of hand strength, providing relevant data to understand the motor capabilities of the hands.