Subcategory: Electrical Engineering
Room: Park Tower 8216
Biya Haile - Georgia Institute of Technology
Co-Author(s): Principal Investigator: Dr. Oliver Brand, Georgia Institute of Technology, Atlanta, Georgia Mentor: Devin K. Brown, Georgia Institute of Technology, Atlanta, Georgia
At present time, chemical sensors are prevalent devices that provide information about pollutants in the air and water. Microelectromechanical systems (MEMS) are one of the popular platforms for portable and low-power chemical sensors. The MEMS-based chemical sensor used in this research consists of a polymer-coated, microfabricated mass-sensitive resonant cantilever for gas-phase chemical detection of volatile organic compounds (VOCs). While a thick polymer sensing film on top of the microfabricated sensor improves sensor sensitivity, it also slows down the sensor response, as analyte needs to diffuse into the relatively thick sensing film.
The main goal of the project is to modify the surfaces of the (silicon-based) microsensors with 3D-printed nanoscale features to ultimately have sensing films that combine high sensitivity and short response time. Thereby, high-surface area, nano-structured sensing films are a way to improve response times while still providing sufficient sensor sensitivity. The 3D nanoscale features are achieved using the Nanoscribe Photonic Professional GT, a commercial 3D lithography system with sub-micrometer resolution based on 2-photon polymerization. This technology is able to write arbitrary-shaped 3D patterns with a high resolution into a solvent-free photoresist (UV light-sensitive polymer). The 3D lithography system is located in the Institute for Electronics and Nanotechnology Organic Cleanroom, which is a Georgia Tech shared-use cleanroom facility. In the project, the 3D direct-write lithography system was used to write high-surface-area nano-patterns, such as nano-cylindrical pillar arrays, directly on the sensing surfaces of silicon-based hammerhead resonators.
A main goal of the project is to identify the optimal process parameters such as the height and diameter of the nano-cylindrical pillars, the laser power, scan speed, hatching, and slicing pitch, as well as the photoresist developing procedure, all of which directly affect the overall integrity of the written 3D structure. Finally, one of the challenging parts of the project is to write 3D nano-patterns directly onto already fabricated micro-sensors, rather than on standard blank, un-patterned substrates, such as silicon wafers or glass slides.
Funder Acknowledgement(s): Georgia Tech Institute for Electronics and Nanotechnology (IEN) staff ; Integrated Sensing Systems lab members: Hommood Alrowais, Steven A Schwartz, Mingu Kim
Faculty Advisor: Dr. Oliver Brand, email@example.com
Role: Developed processes on the 3D direct-write lithography system to write high-surface-area nanopatterns, such as nano-pillar arrays. Trained to use the Scanning Electron Microscope (SEM) to investigate and study nanoscale components in the project such as the cantilever-type resonators inside the MicroElectroMechnical Sensors (MEMS). Analyzed and documented all test results to publish a final report 'Microsensors with Nanostructured Surfaces Fabricated by 3D Lithography'.