A CMOS-Microfluidic Chemiluminescence Contact Imaging Microsystem

Abstract

A hybrid CMOS-microfluidic microsystem for chemiluminescence and electrochemiluminescence-based biochemical sensing is presented. The microsystem integrates a two-layer soft polymer microfluidic network and a CMOS imager fabricated in a standard 0.35- <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\mu$</tex></formula> m technology. The CMOS imager consists of a 64 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\,\times\,$</tex> </formula> 128-pixel array interdigitated with a 32 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$\,\times\,$</tex></formula> 64 electrolessly plated nickel–gold microelectrode array. A two-transistor reset path technique attenuates the subthreshold leakage current of the reset transistor which constitutes a significant portion of the dark current. An active reset technique, in-pixel flicker noise cancellation, and pixel binning contribute to noise reduction. The imager achieves a low dark current of 3.6 nA/cm <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$^{2}$</tex></formula> for photodiode reset voltages as high as 2.3 V, noise of 110 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\mu$</tex> </formula> Vrms with maximum time of photon integration of 90 s, and a dynamic range of 67.8 dB. The CMOS-microfluidic microsystem is validated in on-chip chemiluminescence and electrochemiluminescence detection of luminol.