CMOS nanofluidics

Abstract

Diagnostic tests are essential to medical practice. In vitro diagnostics is a market worth US$ 40-45 billion. Diagnostic tests are usually conducted in centralized laboratories, equipped with expensive instrumentation and staffed with trained personnel. An important part of clinical diagnosis involves protein and DNA sensing. Significant effort is made to make protein and DNA sensing more accessible and affordable, through micro and nano-technologies. However, typical commercial and academic devices for molecular sensing suffered needs for external equipment, high cost and large form factors. In this work, we propose a self-contained point-of-care platform based on complementary metal oxide semiconductor (CMOS). CMOS platform has the capability of pattern features at the scale of nanometers. Important electronic functions in bio-sensing, such as amplifiers, counters and drivers are routinely implemented in CMOS. With the introduction of photonic and nanofluidic functionalities in this thesis, a CMOS chip can potentially perform biomolecular sensing without the aid of external equipment, hence becoming true lab-on-chip devices. This thesis presents the methods developed to introduce nanofluidic and photonic devices in commercial CMOS chips. We first introduce a method to fabricate nanofluidic channels in CMOS by using the transistor gate polysilicon as a sacrificial layer. A nanochannel with critical dimension of 100nm and length of 200 [mu]m is fabricated. Actuation and separation of bio-molecules in the nanochannel with electrophoresis is demonstrated. We then incorporate avalanche photodiodes (APD) in CMOS. Additionally, a packaging method is introduced to work with CMOS chips with size of a few square millimeters. With components mentioned above, clinical applications, such as gene mapping for virus identification and protein separation for cancer diagnosis and monitoring, could potentially run on a chip without external equipment.