A high efficiency label-free photonic biosensor based on vertically stacked ring resonators

In this paper we propose an optical biosensor based on two vertically stacked Silicon on Insulator (SOI) micro-ring resonators interacting with a microfluidic ring channel. This device behaves as a resonant optical coupler and it is very sensitive to the variation of the coupling coefficient between the two vertically stacked ring resonators. A ring microfluidic channel is proposed in the coupling region between the two vertically stacked ring resonators. The inner walls of the channel are funzionalized in order to the trap a specific biological species. Assuming a biotin-streptavidin system, the straptividin trapping gives rise to a change of the biological thickness of about 3 nm. This thickness increase of the deposited layer leads to a consequent change in the coupling strength between the two rings. These theoretical predictions have been validated by using both 3D Finite-Difference Time-Domain (FDTD) and 3D full-vectorial Finite Element Method (FEM) approaches. Moreover, by appropriately choosing the design parameters of the micro-resonant structure, we evaluate a sensitivity of the spectral response to the streptavidin adlayer variation of about 20% nm−1 for TE polarization and 34% nm−1 for TM polarization, which represents an important achievement to obtain selective SOI bio-sensors with ultra-high resolution

Factors associated with climacteric symptoms in women around menopause attending menopause clinics in Italy

Objective: To obtain data on correlates of climacteric symptoms in women around menopause attending menopause clinics in Italy. Methods: Since 1997 a large cross sectional study has been conducted on the characteristics of women around menopause attending a network of first level menopause outpatient's clinics in Italy. A total of 66,501 (mean age 54.4 years) women are considered in the present paper. Results: The odds ratios of moderate and severe hot flashes/night sweats were lower in more educated women and (for severe symptoms only) in women reporting regular physical activity. Depression, difficulty to sleep, forgetfulness and irritability tended to be less frequent in more educated women and (depression only) in women reporting regular physical activity. Parous women reported more frequently these symptoms. Conclusions: This large study confirms in Southern European population that low education, body mass index and low physical activity are associated with climacteric symptoms. Parous women are at greater risk of psychological symptoms