Nanomaterials and Sensors
Scanning Probe Microscopy Laboratory | Quartz Tuning Fork Sensors Laboratory

EMI shielding refers to the reflection and/or absorption of EM radiations using a material; the material acting as a shielding material prevents the penetration of radiations of high frequencies such as radio waves. Nanomaterials are highly sought after for their immensely tunable material properties which result in good shielding capabilities, not only in the microwave regions but also in other regions of the EM spectrum. E.g., reduced graphene oxide can be modified and conjugated with magn­etic materials to obtain electrical and magnetic properties tailor-made for varied applications.

The concept of negative refractive index was introduced by Vaselago which was realized by using metallic wires and split-ring resonators to separately demonstrate negative permittivity and negative permeability materials, respectively, in the 1990s by Pendry et al. Later, Smith et al. experimentally realized these structures in the microwave regime by using both the structures simultaneously in specific ways to produce Left-Handed Materials (LHMs). Such materials have unique proper- ties which depend on the “meta atomic structure”, rather than the constitution of the materials.

QTFs are U-shaped quartz crystal mechanical transducers whose mechanical properties can be monitored by measuring the changes in resonant frequency which are identified in the form of an electrical signal. The high-quality factor (nearly 10 000 in vacuum and about 1000 in air) and affordable price (less than $0.05) allow the QTFs to be accurate as well as affordable. A polymer element atop the tines of the QTF acts as the sensing element for the QTF sensor and causes a change in the resonant frequency based on its interaction with the analyte and is used for volatile organic compound sensing and breath analysis

Scanning probe microscopy (SPM) is a branch of microscopy that forms images of surfaces using a physical probe that scans the specimen. Forces acting between nano-sized cantilever tip and sample are measured using this instrument. Research interests lie in applications including Electrostatic Force Microscopy, Magnetic Force Microscopy, Conductive Atomic Force Microscopy, Amplitude Modulated- Frequency Modulated Microscopy, Force Spectroscopy, Piezoelectric Force Microscopy.