TAILIEUCHUNG - Intelligent and Biosensors 2012 Part 8

Tham khảo tài liệu 'intelligent and biosensors 2012 part 8', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 166 Intelligent and Biosensors The total free energy in the FL is described by equation 3 based on the Stoner- Wolfarth model Stoner Wolfarth 1948 . E Ku sin2 0 2 Nz - Nx Ms sin2 0 - HMs cos o -0 - HtMs sin0 - HM cos0 3 Where H is the stray field generated by the magnetic nanoparticles which can be divided into Hx and Hy respectively. The demagnetizing factors can be determined by equation 4 William 2001 . Nz 8tw ljl2 w2 Nz 8tw Wl2 w2 4 According to the Stoner- Wolfarth model the magnetization direction of the FL FL is in a single domain state as the sensor size is in submicron range in this model is determined by the minimization of the total free energy as shown in equation 3 . Hence the total free energy with respect to 0 Fig. 1- c is minimized. Our method is to set up a discrete array of 0. The range of this array is from 0 to 2n and the step size is . With such small step size the range of 0 can be considered as a continuous range. By substituting the array into equation 3 the minimized energy and the corresponding 0 can be obtained using a simple algorithm. The next step is to use the following equation 5 to calculate the magnetoresistance MR ratio based on the magnetization spin configuration of GMR biosensor where the magnetization direction of PL is exchange biased to a fixed direction -y . AR R AR A 1 - cos 0f-0P R 2 5 Where 0f and 0p are the angles of the FL and the PL with respect to EA respectively AR R o is the MR ratio of the GMR biosensor when the FL and PL is antiparallel with each other which is also the maximum MR ratio for a GMR biosensor. To evaluate the sensing performance the relative MR change ÔR is needed to be defined by equation 6 . ẵR AR R wlthout - AR R wlth AR R 0 X 100 sin0f without - 11 fwith X100 6 Where AR R wth indicates the MR ratio of GMR biosensors due to the nanoparticle sensor agents immobilized on the surface of FL AR R without indicates the MR ratio without nanoparticle especially SPNSA on the surface of FL. Moreover

TỪ KHÓA LIÊN QUAN
Đã phát hiện trình chặn quảng cáo AdBlock
Trang web này phụ thuộc vào doanh thu từ số lần hiển thị quảng cáo để tồn tại. Vui lòng tắt trình chặn quảng cáo của bạn hoặc tạm dừng tính năng chặn quảng cáo cho trang web này.