PROJECTS
Wearable Electrochemical Biosensors
Wearable chemical sensor technologies enable the opportunity to continuously collect physiological information on an individual’s health status. This is in contrast to traditional blood draws and subsequent analysis. Using glucose oxidase as a model enzyme I compare several fabrication methods and describe an optimized glucose monitoring sensor which works in open circuit potential with good selectivity and sensitivity over a glucose concentration range of 50 to 300 µM. The sensors maintain good sensitivity of more than 2000 nA/mM after two weeks. The current drifting is minimal and reproducible and device can be made.
Image credit: Maryam Salari
Development & Characterization of Fluorescently Labeled ENMs for Nanotoxicological Studies
The use of fluorescent tagged nanomaterials has become a fundamental tool in the field of monitoring autophagy, nanotoxicological studies, and therapeutic devices. This technique enables tracking the nanoparticles (NPs) translation through the cell. However, there are certain drawbacks when dealing with fluorescently tagged engineered nanomaterials (ENMs); such as leaching the dye from NPs, or unbound dyes in the solutions leading to incorrect quantification of nanomaterials. Different Fluorophore molecules are therefore conjugated to the ENMs to address the issues related to the labeling strategies, photostability, and dye detachment as a role of pH change.
Image credit: Maryam Salari
Glycerol Carbonate (ethyl/butyl/benzene) Electrolytes
The increased number of electrical energy storage (EES) systems utilized in everyday products along with the demand for more reliable and safer products that provide high energy densities with faster response times over an extended range of temperatures are catalyzing advances across all areas of EES technology. I have explored the preparation and performance evaluation of a high voltage lithium ion supercapacitor (LIC), comprised of activated carbon electrodes and a novel, environmentally friendly alkyl carbonate electrolyte based on glycerol containing a Li salt, that operates at a wider range of temperatures.
Image credit: Maryam Salari
Li-ion insertion and transference occurs through the host network-activated carbon interplanar spaces. The EtOPC electrolyte containing 1M Li-salt affords Li-intercalation at higher sweep rates and increases lithium uptake by the electrodes.
Synthesis & Application of Room Temperature Ionic Liquids (RTILs)
Room temperature Ionic liquids (RTILs) are being explored as safe and stable compounds to replace the conventional organic based electrolytes. The strong ionic interactions within the ions result in negligible vapor pressure, non-flammability, and thermal and electrochemical stability. Their biggest challenge is their high flow activation energy at ambient conditions, which restricts their ionic conductivity and in turn reduces the electrochemical performance at low temperature conditions. Therefore our big goal is to overcome the flow resistivity of these solvents at lower temperatures as an electrolyte compound for a safe and efficient energy storage device.
Image credit: Maryam Salari
Tubular TiO2 Nanostructures: Towards Safer Microsupercapacitor
Self-organized tubular metal oxide nanostructures, synthesized through straightforward and efficient techniques, have resulted in many breakthroughs yet are underutilized in the energy and microdevice fields. I have studied the fabrication and characterization of unique biocompatible energy storage devices that use self-assembled titanium dioxide (TiO2) and a physiological fluid such as PBS as the electrolyte, with no need to use toxic conventional acidic or alkaline electrolytes. Achieving high capacitance through the use of a neutral aqueous electrolyte, combined with the biocompatibility of TiO2 and Ti films open up new avenues for the investigation of these materials for energy harvesting applications in biological media.
Image credit: Maryam Salari
Crystallographic Disorder Engineering of Un-Doped TiO2 Nanotube
The trade-off between performance and complexity of the device manufacturing process should be balanced to enable the economic harvest of solar energy. I have studied a strategy to achieve efficient solar photocatalytic activity in TiO2 through controlled phase transformation and crystallographic disorder engineering in the surface layers of TiO2 nanotubes. This approach enabled to fine-tune the bandgap structure of undoped TiO2 according to our needs while simultaneously obtaining robust separation of photo-excited charge carriers. Introduction of specific surface defects also assisted in utilization of the visible part of sunlight to split water molecules for the production of oxygen.
Image credit: Maryam Salari
TiO2 Nanotubes Synthesis
Rational design and processing are critical to the fabrication of high performance architectures. Although the fabrication of titania nanotube (TN) array films has been studied extensively during the last decade, fabrication of ordered nanoporous titania structures at ambient conditions still remains a challenge. I have studies the fabrication of tubular structures as well as hybrid TN/nanopore layers by altering the electrochemical conditions during titanium anodization. The electrochemical and photocatalytic properties of nanolayers at different stages of the transition from nanoporous to nanotubular titania structure were studied by different electrochemical characterization techniques.
Image credit: Maryam Salari