Research Interests

Advances Sensing Materials

Nanohybrid Sensing Materials:

The special properties of smart sensing materials originate from their engineered structure. We have developed a unique electrochemical approach to fabricate various layered composite thin films consisting of nanomaterials and conducting polymers, called nano-veneers. Nano-veneers with carbon nanotubes, graphene, nanowires, and nanoparticles can be created through in situ electropolymerization. Different from traditional homogeneous composite materials, the nano-veneers can maintain the shape, position, geometry, and orientation of nano-building blocks on their surfaces, giving the materials hetero-sensing properties. These free-standing, transparent, flexible, and highly conductive nano-veneers are particularly attractive in areas of flexible sensors fabrication.

Hierarchical Colorimetric Sensing Materials:

We have developed hierarchical colorimetric sensing materials by integrating material properties at different spatial scales to enhance the sensitivity, and minimize humidity and interference effects. These materials imitate nature, which organizes biological tissues in hierarchical structures to achieve complex and sophisticated functions most effectively. The hierarchical colorimetric sensing materials are featured with uniformly formed nano-scaled crystalline sensing sites in the micron-scaled matrix. The hierarchical colorimetric sensing materials approach is universal and wearable-friendly.

Molecularly Imprinted Polymers:

Molecularly imprinted polymers (MIPs) are synthetic polymer receptors with binding sites that have high affinity and specificity for targeted molecules. The MIPs mimic the natural antibody-antigen systems. Their high selectivity originates from the shapes and functional groups of the cavities in the polymer matrix. We have developed MIPs that are sensitive (ppb level), selective, and stable for organic volatile organic compounds (VOCs) sensing. These MIPs can be used for personal environmental exposure or health biomarker tracking.

Related Publications:

1. Xiaojun Xian, Liying Jiao, Teng Xue, Zhongyu Wu, Zhongfan Liu. Nanoveneers: An Electrochemical Approach to Synthesizing Conductive Layered Nanostructures, ACS Nano, 5, 4000-4006 (2011)

2. Zhongfan Liu, Liying Jiao, Yagang Yao, Xiaojun Xian, Jin Zhang. Aligned, Ultralong Single-Walled Carbon Nanotubes: From Synthesis, Sorting, to Electronic Devices, Advanced Materials, 22, 1 (2010)

3. Devon Bridgeman, Javier Corral, Ashley Quach, Xiaojun Xian, Erica Forzani. Colorimetric Humidity Sensor Based on Liquid Composite Materials for the Monitoring of Food and Pharmaceuticals, Langmuir, 30, 10785–10791 (2014)

4. Yue Deng, Cheng Chen, Xingcai Qin, Xiaojun Xian, Terry L. Alford, Hyung W. Choi, Francis Tsow, Erica S. Forzani, Aging Effect of a Molecularly Imprinted Polymer on a Quartz Tuning Fork Sensor for Detection of Volatile Organic Compounds, Sensors and Actuators B: Chemical, 211, 25-32 (2015)

5. Jingjing Yu, Di Wang, Vishal Varun Tipparaju, Francis Tsow, and Xiaojun Xian, Mitigation of Humidity Interference in Colorimetric Sensing of Gases, ACS Sensors, 6, 2, 303-320 (2021)

6. Jingjing Yu, Francis Tsow, Mora, S. Jimena, Vishal Varun Tipparaju, and Xiaojun Xian, Hydrogel-Assisted Colorimetric Sensors with High Humidity Tolerance for Environmental Gases Sensing, Sensors and Actuators B: Chemical, 345, 130404 (2021)