High-resolution cantilever biosensor resonating at air-liquid in a microchannel.
We have developed a highly mass-sensitive cantilever resonating at the interface of air and liquid. The cantilever is applicable as a biosensor by measuring its resonance frequency shift associated with the selective trapping of target molecules. One surface of the cantilever facing to the liquid is functionalized for label-free detection, while the opposite side is exposed to air to improve the resonance characteristics, such as the quality factor. The quality factor at resonance is 15, which is 50% higher than the same cantilever in liquid. The beam was excited through the photothermal effect of a power modulated laser and detected by laser Doppler velocimetry. Due to the proposed configuration, the signal-to-noise-ratio is 5.7 times larger than the completely submerged case. A micro-slit around the cantilever separates the air and liquid phases at a meniscus. We analyzed the cantilever motion including the meniscus membrane, and examined the effect of surface tension by applying various solutions. A slit width of 6 μm was found to give the best performance within the few prototypes. We measured the covalent immobilization of antibody molecules on a cantilever surface for three different concentrations: 20, 40, and 80 μg ml(-1). The kinetics measured by both resonance frequency shift of the cantilever and fluorescent intensity showed good agreement.
Center for International Research on Micronano Mechatronics (CIRMM), Institute of Industrial Science (IIS), the University of Tokyo, 4-6-1 Komaba Meguro, Tokyo, 153-8505, Japan. jwook@iis.u-tokyo.ac.jp
Jungwook
J
Park
Shuhei
S
Nishida
Pierre
P
Lambert
Hideki
H
Kawakatsu
Hiroyuki
H
Fujita
D000388:Air; D055910:Antibodies, Immobilized / Q000737:chemistry; D015374:Biosensing Techniques / Q000295:instrumentation / Q000379:methods*; D007700:Kinetics; D017078:Laser-Doppler Flowmetry; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation*; D059629:Signal-To-Noise Ratio; D012822:Silicon Dioxide / Q000737:chemistry; D013500:Surface Tension
D055910:Antibodies, Immobilized; D012822:Silicon Dioxide