Low-environmental-interference & highly-sensitive TMR biosensor for in-vitro diagnosis application

The Tunnel Magnetoresistance (TMR) biosensor with different magnetic tunnel junction (MTJ) aspect ratios was developed. With the specific designs and the process development, the sensing distance of the active sensor could be shortened to 74.2 nm to obtain larger magnetic bead (MB) induced signal and the reference sensor, whose sensing distance was 350 nm thicker than that of the active sensor, was used as the baseline during the detection to eliminate the environment noise. The simulation method which could well characterize the TMR element was also developed. Finally, the experimental results of the MB detection was shown. W1/L8 MTJ structure, whose resistance was $40 \mathrm{k}\Omega$, had the highest sensitivity $(0.444 \Omega /$MB). Overall, according to the various designs of the MTJ structures, the TMR biosensor with low environmental interference and high sensitivity could be used in variety of the in-vitro diagnosis of Point of Care (PoC) applications in future.