A Wireless, Passive Multimodal Wearable Sensor With Decoupled Sensing Capabilities

Area of Science:

• Materials Science
• Electrical Engineering
• Sensor Technology

Background:

• Developing electronic skin (e-skin) with multi-stimuli sensing capabilities is challenging.
• Existing e-skin technologies often lack superimposed multi-stimuli discrimination, rely on external power, and use wired transmission.
• Overcoming these limitations is crucial for advanced wearable applications.

Purpose of the Study:

• To develop an integrated wireless passive wearable sensor for simultaneous multi-stimuli detection.
• To achieve decoupled sensing of pressure, odor (NO2), and humidity.
• To demonstrate e-skin capabilities exceeding current technologies.

Main Methods:

• Utilized a frequency-division inductance-capacitance (LC) resonator array for sensor design.
• Employed three-dimensional full-wave electromagnetic simulations for performance validation.
• Incorporated a gradient-modulus trilayer hydrogel with micro-pyramidal patterning for pressure sensing.

Main Results:

• Achieved ultrafast pressure sensing (5/6 ms response/recovery) with high sensitivity (6.15 MHz·kPa^-1).
• Demonstrated trace-level (200 ppb) NO₂ detection, unaffected by humidity or pressure.
• Exhibited high sensitivity across a wide humidity range (2%-98% RH) with minimal cross-sensitivity.

Conclusions:

• The developed wireless passive sensor enables simultaneous, decoupled detection of pressure, NO₂, and humidity.
• The e-skin surpasses previous devices in selectivity and performance under complex stimuli.
• This technology offers a transformative approach for diverse wearable applications.