Extending the Longevity of Fluorescence-Based Sensor Arrays Using Adaptive Exposure

Fluorescent microbead sensor arrays were prepared to determine sensor array longevity. Sensor longevity is limited by photobleaching of the dyes attached to the microbeads and presents one of the biggest drawbacks of most fluorescent dye-based arrays. Responses of an array of organic vapor sensors were acquired for 2 weeks to evaluate the sensor performance over time. Photobleaching effects were overcome in two ways: (1) by limiting the excitation light power and gradually increasing the power at a rate comparable to the sensor photobleaching rates and (2) by illuminating subsections of the array through an optical slit. Both approaches extended the longevity of a sensor array. During the longevity study, the sensor arrays were employed to test their ability to correctly distinguish between responses to seven vapors. A high classification accuracy (99.8%) was obtained after 17,700 exposures for vapor responses collected over two weeks using only approximately 8% of the array's surface area.