Degree Type


Date of Award


Degree Name

Master of Science


Electrical and Computer Engineering


Electrical Engineering

First Advisor

long que


This paper reports, for the first time, an aptamer-based nanopore thin film sensor for detecting the ophylline in buffer and complex fluids. In my experiments, I created the sensor and found that it could help us to better test theophylline than an antibody-based detection sensor. The following is a detailed explanation of the sensor creation and the experimental process.

Anodic aluminum oxide (AAO) has been investigated and applied in numerous products since the 1970s. It is a highly-arrayed porous nanostructure as shown in Figure 1. The pore size normally ranges from tens to hundreds of nanometers, and the aspect ratio could be higher than 40:1. Application areas of AAO include biomedical sensing, energy storage, template-based nanofabrication, electronics, etc. In my experiment, I applied AAO to the process of creating a sensor.

In my experiments, I chose RNA aptamer rather than antibodies because its molecules

overcome the weakness of antibodies. The 33 nts RNA aptamer sequences used were found to recognize and selectively bind theophylline (Figure 2) [1]. Moreover, aptamers are easy to synthesize, have both excellent heat stability and a wide tolerance range of PH and salt concentration, and is much less costly than antibodies.

The first study used an aptamer-based nanopore thin film sensor to detect theophylline in the buffer and complex fluids. I first fabricated the nanopore thin film sensors with a microfluidic interface, then demonstrated the surface functionalization procedure of the sensor. I then used optical transducing signals to detect the fringes followed by using the sensor as a reference sensor to further cancel out the non-specific binding effect; theophylline in low concentration (0.2μM), caffeine, theobromine, and plant extract were successfully detected. The experiment showed that this aptamer-based sensor had good specificity and selectivity, allowing me to further test theophylline in serum.

The second study used an optical aptamer-based plant hormone sensor with a microfluidics capillary interface. I adopted the exact same methodology and sensor from themy first study and further designed an optical aptamer-based sensor with a microfluidics capillary interface to upgrade the testing process. Such a microfluidics capillary interface film censor was created and how my two successful experiments were performed. The research outcome is that an aptamer-based label-free sensor for optically detecting theophylline has been demonstrated for the first time. It performs much better than its competitors and has a promising future in further

applications in similar experiments.

Copyright Owner

Silu Feng



File Format


File Size

58 pages