DocumentCode :
3122721
Title :
Liquid-phase detection of biological targets with magnetic markers and high Tc SQUID
Author :
Uchida, Seiichi ; Higuchi, Yuji ; Ueoka, Yoshihiro ; Yoshida, Takafumi ; Enpuku, Keiji ; Adachi, Shuichi ; Tanabe, Kazuki ; Tsukamoto, Arata
Author_Institution :
Dept. of Electr. Eng., Kyushu Univ., Fukuoka, Japan
fYear :
2013
fDate :
7-11 July 2013
Firstpage :
1
Lastpage :
3
Abstract :
We developed a highly sensitive HTS SQUID system for liquid-phase detection of biological targets using Brownian relaxation of magnetic markers. The SQUID was made of a ramp-edge Josephson junction using RE123-based multilayer process, and it showed a flux noise of 7.5 micro flux-quantam/Hz1/2 in the white noise region. The 1/f noise was 14 micro flux-quantam/Hz1/2 at f = 1 Hz when the SQUID was operated with AC bias mode. Using the SQUID system, we detected a biological target called biotin. In the experiment, biotins were fixed to a large polymer bead with a diameter of 3.3 micron meter. Streptavidin-coated magnetic markers were used for the detection. The bound and unbound (free) markers were magnetically distinguished using the difference in their Brownian relaxation time, i.e., without using the washing process to separate them. The minimum detectable number of biotins was as low as 104, corresponding to a sensitivity of 4.8×10-19 mol/ml. This result indicates a high sensitivity of the developed method.
Keywords :
1/f noise; SQUIDs; high-temperature superconductors; 1/f noise; Brownian relaxation time; RE123-based multilayer process; SQUID; Streptavidin-coated magnetic markers; biological targets; biotins; flux noise; liquid-phase detection; polymer bead; ramp-edge Josephson junction; size 3.3 mum; white noise region; Magnetic flux; Magnetic multilayers; Magnetic separation; Magnetic tunneling; Noise; Polymers; SQUIDs; HTS SQUID; immunoassays; liquid phase detection; magnetic marker;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Superconductive Electronics Conference (ISEC), 2013 IEEE 14th International
Conference_Location :
Cambridge, MA
Print_ISBN :
978-1-4673-6369-3
Type :
conf
DOI :
10.1109/ISEC.2013.6604304
Filename :
6604304
Link To Document :
بازگشت