Internet of things (IoT) systems for precision agriculture enabled by biodegradable sensors have the potential to lead to more efficient use of water and fertilizers. Here, a capacitive moisture sensor designed to operate in the 902-928 MHz frequency band is screen-printed on a fully biodegradable paper substrate with a surface that is improved via the infiltration of cellulose nanofibrils (CNFs). Sensor trace quality on the CNF composite substrate is comparable to traces printed on polyimide and superior to traces printed on conventional cardstock. Furthermore, the moisture response of the substrate is shown to be enhanced via the CNF infiltration. Small feature sizes achievable through screen- printing on the CNF composite enable their use in RF passive wireless sensing systems. The fabricated sensors are shown to have a self-resonance well above the operating frequency band.

The Turner Research Group investigates problems at the nexus of mechanics, manufacturing, and materials, with a particular emphasis on research questions involving small-scale systems and interfaces. We focus on understanding the underlying mechanics and materials science of the problems that we investigate and exploit this understanding to advance the capability of existing technologies and to develop novel processes, materials, and devices. This is achieved by leveraging our core expertise in micro- and nano-systems, adhesion and fracture, experimental and computational mechanics, and advanced manufacturing. Ongoing projects include structured surfaces and materials with unique adhesion and fracture behavior, additive manufacturing of cellulose nanomaterials, soft robotic grasping, nanocomposites, and manufacturing processes for flexible hybrid electronics and sensors. 

The Biotics Lab incorporates devices into microsystems enabling new functionality in health/edge IoT. They invent new devices or improve existing concepts leading to breakthroughs in performance for edge devices. They optimize the properties of emerging active materials and develop nanofabrication techniques for forming devices.

PUBLISHED PAPERS

Fabrication and Characterization of Cellulose-Based Materials for Biodegradable Soil Moisture Sensors, 2022 IEEE Sensors

Fabrication and Characterization of Soil Moisture Sensors on a Biodegradable, Cellulose-Based Substrate, IEEE Sensors Journal

 Powerpoint slides from lab