Won Woo Cho

A Small Dual-Band Inverted-F Antenna With a Twisted Line

A twisted-line inverted-F antenna (IFA) is proposed for dual-band applications. The antenna features a twisted line for dual bands and a parasitic line for additional resonance. The twisted-line IFA has wideband characteristics in the high frequency band due to the mergence of the resonances of the twisted line and the parasitic line. The electric size of the antenna is 0.109 lambda x 0.025 lambda x 0.0025 lambda, and its length is about 44% that of a conventional IFA. The twisted-line IFA was fabricated on a thin FR4 substrate, and its performance was measured. The antenna operates at 930 MHz with a bandwidth of 30 MHz, and at 1.7 GHz with a bandwidth of 350 MHz for S11 less than -6 dB; the maximum radiation efficiencies were 48% at 937 MHz and 80% at 1.645 GHz.

A highly sensitive plasma-based amyloid-β detection system through medium-changing and noise cancellation system for early diagnosis of the Alzheimer's disease

We developed an interdigitated microelectrode (IME) sensor system for blood-based Alzheimer’s disease (AD) diagnosis based on impedimetric detection of amyloid-β (Aβ) protein, which is a representative candidate biomarker for AD. The IME sensing device was fabricated using a surface micromachining process. For highly sensitive detection of several tens to hundreds of picogram/mL of Aβ in blood, medium change from plasma to PBS buffer was utilized with signal cancellation and amplification processing (SCAP) system. The system demonstrated approximately 100-folds higher sensitivity according to the concentrations. A robust antibody-immobilization process was used for stability during medium change. Selectivity of the reaction due to the affinity of Aβ to the antibody and the sensitivity according to the concentration of Aβ were also demonstrated. Considering these basic characteristics of the IME sensor system, the medium change was optimized in relation to the absolute value of impedance change and differentiated impedance changes for real plasma based Aβ detection. Finally, the detection of Aβ levels in transgenic and wild-type mouse plasma samples was accomplished with the designed sensor system and the medium-changing method. The results confirmed the potential of this system to discriminate between patients and healthy controls, which would enable blood-based AD diagnosis.