Programmable Hybrid Integrated Circuit/Microfluidic Chips - Point-of-Care Diagnostics on a Chip - page 28

Fig. 2.5 60 wires.

( b ) The pixels are charged to 0 or 50 V to generate electric fields. ( c ) The wires carry current to
generate magnetic fields. Magnetic field maxima occur where two orthogonal wires overlap

( a ) The third-generation chip consists of an array of 60 61 pixels and 60

wires, shown in Fig. 2.5 b. The wires are activated by running a 120-mA DC current
through them. Magnetic field maxima are generated where two perpendicular wires
overlap, creating a trap for magnetic particles [ 13 ].

2.4 Functions Performed by Hybrid Integrated

Circuit/Microfluidic Chips

Many functions have been implemented on integrated circuits for medical diag-
nostics. Droplets and cells can be transported, deformed, porated, merged, and
heated [ 10 - 15 ]. Virtual microfluidic channels, defined by electric field boundaries,
have also been implemented. Temperature and conductance sensors have also been
built into IC's [ 14 , 17 ]. These functionalities are described in further detail in
the remainder of this chapter. Several important operations have also yet to be
implemented on an integrated circuit platform for diagnostics. These include droplet
making, mixing, and color and fluorescence sensing. These will round off the
remainder of this chapter.

2.4.1 Positioning/Programmable Channels

Positioning cells and droplets, shown in Fig. 2.6 , is a critical function underpinning
the usefulness of integrated circuit technology for medical diagnostics. Reagents
must be transported from storage areas onto the chip and mixed and reacted with