Towards a MEMS Force Sensor via the Electromagnetic Principle.

Area of Science:

• Physics
• Electrical Engineering
• Materials Science

Background:

• Advancements in force measurement are driven by new materials and sensor technologies.
• Emerging demands necessitate miniaturized and easily applicable force sensors, such as micro electromechanical systems (MEMS).
• Existing force sensors operate on diverse principles and find applications across various industries, including medicine.

Purpose of the Study:

• To propose and validate a novel force measurement principle based on force-to-time-delay conversion.
• To investigate the use of micro electromechanical systems (MEMS) and compact compliant mechanical bodies (CCMB) as force transducers.
• To analyze the reverse influence of a transducer's resonant frequency on the surrounding electromagnetic field.

Main Methods:

• Developed a force measurement system utilizing a compact compliant mechanical body (CCMB) with an embedded parallel resonant circuit (PRC) as a transducer.
• Employed a force-to-time-delay conversion principle, measuring force by observing the transducer's influence on a voltage-controlled oscillator (VCO) DC supply current.
• Validated the proposed method through mathematical analysis, simulation, and prototype measurements.

Main Results:

• Demonstrated that the transducer's resonant frequency has a detectable reverse influence on the VCO DC supply current.
• Determined applied force by analyzing the position of the DC supply current ripple during the VCO frequency sweep.
• Validated the CCMB prototype for forces up to approximately 2.5 N at a sampling frequency of 23 kHz, with measured time-delays ranging from 14.5 µs to 27.4 µs.

Conclusions:

• The proposed force-to-time-delay conversion principle offers a viable method for precise force measurement.
• The integration of MEMS and CCMB with PRC transducers shows promise for miniaturized and effective force sensing.
• The study successfully verified the method's functionality through simulation and prototype testing, paving the way for practical applications.