Label free CMOS DNA image sensor based on the charge transfer technique

This paper describes a label free and fully electronic 32 × 32 CMOS DNA image sensor fabricated in a 1-poly 1-metal CMOS technology, suitable for inexpensive and highly integrated applications. The pixel operates using the charge transfer technique. DNA immobilization and hybridization on the silane-coated surface are detected, as well as variations in the silane coating. Significant output voltages of 76.4 ± 16.5 mV and 64.5 ± 15.7 mV were measured after immobilization and hybridization of DNA molecules containing 22 bases. From these results, the immobilized and hybridized DNA densities were estimated. These were 6.3 ± 1.4 × 108 cm−2 and 5.3 ± 1.3 × 108 cm−2, respectively. The DNA detection limit was calculated to be approximately 2.7 × 107 cm−2 molecules (22 bases). Thanks to its potentiometric detectability, the DNA immobilization and hybridization was successfully verified.