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Floating Chip Mounting System Driven by Repulsive Force of Permanent Magnets for Multiple On-Site SPR Immunoassay Measurements
NTT Microsystem Integration Laboratories, Nippon Telegraph and Telephone Corporation (NTT), Morinosato-Wakamiya, Atsugi-shi, Kanagawa 2430198, Japan
NTT Advanced Technology, Morinosato-Wakamiya, Atsugi-shi, Kanagawa 2430198, Japan
* Author to whom correspondence should be addressed.
Received: 21 August 2012; in revised form: 24 September 2012 / Accepted: 12 October 2012 / Published: 17 October 2012
Abstract: We have developed a measurement chip installation/removal mechanism for a surface plasmon resonance (SPR) immunoassay analysis instrument designed for frequent testing, which requires a rapid and easy technique for changing chips. The key components of the mechanism are refractive index matching gel coated on the rear of the SPR chip and a float that presses the chip down. The refractive index matching gel made it possible to optically couple the chip and the prism of the SPR instrument easily via elastic deformation with no air bubbles. The float has an autonomous attitude control function that keeps the chip parallel in relation to the SPR instrument by employing the repulsive force of permanent magnets between the float and a float guide located in the SPR instrument. This function is realized by balancing the upward elastic force of the gel and the downward force of the float, which experiences a leveling force from the float guide. This system makes it possible to start an SPR measurement immediately after chip installation and to remove the chip immediately after the measurement with a simple and easy method that does not require any fine adjustment. Our sensor chip, which we installed using this mounting system, successfully performed an immunoassay measurement on a model antigen (spiked human-IgG) in a model real sample (non-homogenized milk) that included many kinds of interfering foreign substances without any sample pre-treatment. The ease of the chip installation/removal operation and simple measurement procedure are suitable for frequent on-site agricultural, environmental and medical testing.
Keywords: SPR; on-site; portable; immunoassay; magnet
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Horiuchi, T.; Tobita, T.; Miura, T.; Iwasaki, Y.; Seyama, M.; Inoue, S.; Takahashi, J.-I.; Haga, T.; Tamechika, E. Floating Chip Mounting System Driven by Repulsive Force of Permanent Magnets for Multiple On-Site SPR Immunoassay Measurements. Sensors 2012, 12, 13964-13984.
Horiuchi T, Tobita T, Miura T, Iwasaki Y, Seyama M, Inoue S, Takahashi J-I, Haga T, Tamechika E. Floating Chip Mounting System Driven by Repulsive Force of Permanent Magnets for Multiple On-Site SPR Immunoassay Measurements. Sensors. 2012; 12(10):13964-13984.
Horiuchi, Tsutomu; Tobita, Tatsuya; Miura, Toru; Iwasaki, Yuzuru; Seyama, Michiko; Inoue, Suzuyo; Takahashi, Jun-ichi; Haga, Tsuneyuki; Tamechika, Emi. 2012. "Floating Chip Mounting System Driven by Repulsive Force of Permanent Magnets for Multiple On-Site SPR Immunoassay Measurements." Sensors 12, no. 10: 13964-13984.