Human Activity Recording Based on Skin-Strain-Actuated Microfluidic Pumping in Asymmetrically Designed Micro-Channels

Area of Science:

• Wearable technology
• Microfluidics
• Biomedical engineering

Background:

• Passive, image-based wearable sensors offer simplified data readout and avoid skin electronics.
• Existing methods for recording human activity via wearables can be complex or require invasive components.

Purpose of the Study:

• To develop and validate a skin-strain-actuated microfluidic pump (SAMP) for passive human activity monitoring.
• To establish an analytical model for the SAMP's operation as a wearable device.
• To demonstrate the SAMP's ability to record and quantify human movements.

Main Methods:

• Fabrication of the SAMP using soft lithography with polydimethylsiloxane (PDMS).
• Development of an analytical model to describe the SAMP's operational mechanism.
• Experimental validation through benchtop tests and human subject trials with the device mounted on skin.

Main Results:

• Analytical predictions and experimental results for the SAMP showed good agreement.
• The SAMP successfully recorded human activity over hundreds of cycles, indicated by a stable liquid meniscus.
• Proof-of-concept experiments demonstrated quantification of single wrist movements and differentiation of shoulder activities.

Conclusions:

• The skin-strain-actuated microfluidic pump (SAMP) is a viable technology for passive, image-based wearable sensing.
• The SAMP can reliably record and differentiate human physical activities without requiring on-skin electronics.
• This microfluidic approach offers a promising alternative for wearable human activity monitoring systems.