A Low-Light CMOS Contact Imager With an Emission Filter for Biosensing Applications.

Area of Science:

• Biomedical Engineering
• Sensor Technology
• Microfabrication

Background:

• Cell detection in biosensing requires high-sensitivity, low-noise imaging systems.
• Existing technologies may face limitations in low-light conditions and specific fluorescence detection.
• Advancements in CMOS technology offer potential for integrated biosensing solutions.

Purpose of the Study:

• To present a fully functional, low-light 128x128 contact image sensor for cell detection.
• To achieve high sensitivity and low noise performance suitable for fluorescence imaging.
• To demonstrate the sensor's functionality and biocompatibility in biosensing applications.

Main Methods:

• Fabrication of a 128x128 contact image sensor using 0.18 µm CMOS technology.
• Implementation of modified active reset (AR) and active column sensor (ACS) readout techniques for low-noise operation.
• Integration of a custom-designed emission filter (PDMS and Sudan II Blue) for fluorescence detection (excitation < 340 nm, emission > 450 nm).

Main Results:

• The fabricated CMOS image sensor exhibits low-noise operation and high sensitivity.
• The integrated emission filter effectively supports fluorescence imaging at specified wavelengths.
• Experimental validation using live neurons and fluorescent micro-beads confirmed system functionality and biocompatibility.

Conclusions:

• The developed low-light contact image sensor is a viable tool for cell detection in biosensing.
• The sensor's performance is well-suited for fluorescence imaging applications.
• The system demonstrates potential for in-situ biological monitoring and diagnostics.