Biochips – fundamentals and applications - Electrochemical Sensors, Biosensors and Their Biomedical Applications - page 366

(a) (b) (c)

FIGURE 11.34 Photograph of fabricated silicon mask (a), molded PDMS ELISA fl ow-through biochip
(b), and image of sample detection at different detection sites (c).

A

B

A-B section detail

Channel cover

Flow-through channel

Counter
electrode

Working
electrode
Plastic or silicon substrate

Working
electrode

Current
collector

Counter electrode

FIGURE 11.35 Flow-through electronic addressable bioarray devices.

of the biochips have to work in buffer solutions or biological fl uids. Due to ionic con-
ductivity, simple row-column (x-y) addressable array electrodes in a buffer are ionically
shorted and cannot be detected for biological events occurring at individual electrodes.
Li et al. disclosed a microfl uidic design to fabricate a fl ow-through electronic array bio-
chip for addressing individual electrodes without the ionic shortage [172]. The design
is shown in Fig. 11.35, in which microchannels are designed to isolate every electroni-
cally connected column or row of electrodes for eliminating the ionic shortage dur-
ing x-y addressing. Although these processes are expensive, slow and not commonly
accessible to researchers, replication of these structures is becoming an emerging and
established fi eld summarized with the term nano-imprint-lithography (NIL). New lab-
on-chip platforms often bring great advantages to their biomedical applications. Li et al.
have reported a biotape device with an array biosensor associated with fl uidic sample
processing components that can be widely used in diagnostic applications [173].