it has been more than half a century since the first application of an
optical sensing device. There are many optical techniques developed
for the detection of various chemical or biochemical interaction,
such as surface plasmon resonance (SPR) biosensors, Mach-Zehnder
interferometry biosensors, and Young interferometry biosensors with
different degrees of detection sensitivity[1–3]. It comes to light that all
the current commercial biosensors have limited usage and detection
sensitivity when multiple test samples or target analytes are concerned
in the absence of chromophoric or fluorescent labeling substances
[3].Recently, well-established commercial mass production technologies of
silicon devices have permitted the pursuing of implementing innovative
device concepts in the development of advanced biosensor devices,
which would be impossible a few years ago. With the aid of the chip
design and micro/nanofabrication technologies,“labonchip”
biosen-sing devices become a major focus of interdisciplinary research and
have attracted significant attentions globally[3–5]. These arrayed
biosensing devices incorporate optical wave guide structures with
microfluidics at chip level, and therefore exhibit superior functionalities
Chinese Materials Research Society and capabilities. They are capable
of real-time, quantitatively and selectively measuring extremely low concentrations of analyte mole-cules without using labeling substance[3,4]. In principle, interferome-try based integrated opto-fluidic biosensors, such as Mach-Zehnder interferometer
[6]and Young interferometer[7], feature the highest detection sensitivity, which are capable of detecting refractive index changesassmallas10
8. Some arrayed interferometry prototype
designs at laboratory level for the parallel detection of a number of
analytes have been reported[8–10]. However, there is no single
commercial device currently available for the detection of multiple
analytes in multiple samples at the above highest detection sensitivity.
This work is based on our previous result[3], which makes use of
interferometry and evanescent field detection principles and methods.
For biosensing device presented in this paper, modular concept is
used by employing standard individual stand-alone sensors as
modules, which can be combined to form an arrayed biosensing
device at chip level. Internal reference channels are integrated on the
same sensing chip to compensate for the variations such as the
refractive indexfluctuations caused by temperature fluctuations,
mechanical changes and unknown binding process in the bulk
samples, which may affect the accuracy and reliability of detection.
Additionally, sensing and reference channels can be grouped at the
chip level according to specific requirement. This enables maximal
flexibility in measuring individual analytes in multiple test samples
simultaneously and instantaneously[3]. For these devices, the
detection limit of molecule concentrations at or even below 10
12M can be obtained. The detection sensitivity of the arrayed
biosensor here is at least 10–100 times higher than that of the most
commonly used commercial SPR biosensors
[3]