Semi-Disposable Chips for CMOS-Based Biosensors

Abstract

Integrating biosensing functions and microfluidics on top of CMOS electronics has enabled a new generation of lab-on-a-chip systems that have addressing, sensing, and data elaboration functions on the same device. Such integration promises to overcome the limitations of existing optical techniques and enable new possibilities for low-cost, low-power and portable devices, particularly for DNA detection [1], genome research [2], point-of-care diagnostics, and neural activity sensing. Although CMOS integration is favorable for such biosensing applications, it brings additional challenges and limitations, such as: (i) the materials used in the CMOS fabrication are not always suitable for bio-measurements due to the issues of bio-compatibility and stability in electrolyte solution; (ii) the packaging leads to additional cost and reliability problems, as the wire bonds have to be protected, and leak-free microfluidic channels and reservoirs have to be implemented; (iii) the disposability of the assay-substrate is a key parameter for the commercialization and the widespread use of the biosensor. In this context, the present study proposes a disposable biosensing layer (fig.1) that can be aligned and temporarily attached to the electronics through flexible interconnections and can be replaced after each measurement to eliminate the cleaning steps and cross-contamination of samples [3]. This idea promises three key benefits: (i) high-density microelectrode array thanks to vertical interconnections; (ii) high-performance operation thanks to circuits in close proximity; (iii) low-cost and configurable biochips by fully decoupling the fabrication of the sensor and the electronics. This paper also presents fully CMOS-compatible TSV fabrication and 3D integration platforms to realize electronics with higher performance and functionality [4].