21.6 A smart CMOS assay SoC for rapid blood screening test of risk prediction

Rapid blood test is essential to disease control, risk assessment and point-of-care testing. Conventional enzyme-linked immunosorbent assay (ELISA) requires several hours or even days to get meaningful results. However, to some fierce contagious diseases, such as Ebola and SARS, the contagion can spread so fast that an instant and massive screening test is needed. A CMOS assay system-on-chip (SoC) offering a fast and cheap disease screening tool can be very helpful in the place where the medical resources are limited and the test is too costly to afford. Unlike the previously proposed CMOS biomolecular detection based on direct detection [1], a sandwiched assay detection protocol is adopted in this work, which possesses high sensitivity, high specificity and is free from pre-purified antigen process. As shown in Figure 1, a human blood sample containing the target biomolecules is applied on the proposed SoC. The test procedure includes blood filtration, biomolecular conjugation, electrolytic pumping, magnetic flushing and detection, automatically controlled by a micro-controller unit (MCU). The biomolecular signal is converted to the electrical signal by a CMOS-based Hall sensor array, as shown in the SEM image of Fig. 21.6.1, where the surface is coated with biomolecular probe. With the integration of the four LEDs and a battery, the detection steps can be indicated, providing an easy self-test point-of-care application.