Enhancing the Output of Self-Powered Cellulose-Based Humidity Sensors by Embedding Covalent Organic Frameworks.

Area of Science:

• Materials Science
• Nanotechnology
• Sensor Technology

Background:

• Atmospheric humidity monitoring is crucial for human life and various applications.
• Self-powered humidity sensors based on the moist-electric effect are desirable for low-power, lightweight, and eco-friendly devices.
• Existing moist-electric effect sensors face challenges with weak and unsustainable electrical output.

Purpose of the Study:

• To develop a novel self-powered humidity sensor with improved electrical output and stability.
• To utilize a hybrid aerogel composed of covalent organic framework (COF) and cellulose nanofibers (CNF) for humidity sensing.
• To demonstrate the sensor's capability in monitoring human respiration and noncontact sensing.

Main Methods:

• Uniformly dispersed COF and CNF to create a humidity-sensitive hybrid aerogel.
• Fabricated a humidity sensor using the COF/CNF aerogel as a substrate for moist-electric effect operation.
• Evaluated the sensor's performance in terms of linearity, electrical output, sensitivity, and stability.

Main Results:

• The COF/CNF aerogel sensor exhibited exceptional humidity response linearity (R² = 0.991).
• Achieved a high open-circuit voltage of 0.84 V and sensitivity of 14 mV/% RH.
• Demonstrated stable voltage output (0.55-0.6 V) for over 5 hours under environmental humidity.

Conclusions:

• The developed aerogel platform provides a practical route for self-powered humidity sensing.
• The synergistic effects of COF and CNF enhance moisture absorption and electrical output.
• The sensor shows potential for environmental monitoring and low-power sensing applications, including respiration monitoring.