Abstract
Ageing population in Europe will increasingly burden the health care
system, e.g. chronic diseases are becoming more and more common and are
influencing the quality of life of rapidly increasing number of people. New
solutions for biomolecular recognition measurements are required to reduce the
number of costly laboratory tests, hospital controls and idle visits to
general practices.
Optical interferometric measurement methods are extremely sensitive and thus
they are very suitable for biomolecular recognition. Usual sensitivity range
for interferometric methods is from 10-5 to 10-8 refractive index units. This
large dynamic range covers well most biomolecular applications. In an
integrated Young interferometer sensor, which we have focused on in our
studies, the incident sensing light is divided into two parallel light paths,
reference and sample path. Sample path has an antibody coating on its surface,
where the measured analyte (antigen) binds specifically and the other light
path acts as a reference of the measurement to compensate, e.g., temperature
fluctuations. This compensation explains the extremely good sensitivity
obtained with most Young interferometers. It also makes the sensor more cost
efficient since there is no need for very precise stabilisation of humidity
and temperature around the sensor chip.
In this paper we present the theoretical and empirical functioning and
sensitivity of two integrated Young interferometers. We have studied the
sensitivity of a channel waveguide based interferometer with integrated
Y-junction as a beam splitter and a vertically integrated dual-slab waveguide
interferometer. The sensitivity of the channel waveguide based Young
interferometer was found to be in the order of 10-8 effective refractive index
units (i.e., in the order of 10-6 refractive index units). Compared to this
conventional channel waveguide based Young’s interferometer; we found that the
dual-slab waveguide interferometer (Farfield Inc.) has the advantages of easy
fabrication and large tolerance to the input coupling beam. The sensor
performance was estimated by using glucose solutions with various
concentrations. Glucose concentrations within physiological range 30mg/dl ~
500mg/dl are of the most interest. As a result the dual-slab waveguide
interferometer yields an average phase resolution of 0.002 rad which
corresponds to an effective refractive index change of 4×10-8 (tai to a
refractive index change of 5×10-6).
Original language | English |
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Publication status | Published - 2007 |
MoE publication type | Not Eligible |
Event | International Symposium Bio meets Nano and IT - Halle, Germany Duration: 4 Dec 2007 → 4 Dec 2007 |
Conference
Conference | International Symposium Bio meets Nano and IT |
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Country/Territory | Germany |
City | Halle |
Period | 4/12/07 → 4/12/07 |
Keywords
- Biomolecular recognition
- biosensor
- interferometry