Stefania Dante

All-optical phase modulation for integrated interferometric biosensors

We present the theoretical and the experimental implementation of an all-optical phase modulation system in integrated Mach-Zehnder Interferometers to solve the drawbacks related to the periodic nature of the interferometric signal. Sensor phase is tuned by modulating the emission wavelength of low-cost commercial laser diodes by changing their output power. FFT deconvolution of the signal allows for direct phase readout, immune to sensitivity variations and to light intensity fluctuations. This simple phase modulation scheme increases the signal-to-noise ratio of the measurements in one order of magnitude, rendering in a sensor with a detection limit of 1.9·10⁻⁷ RIU. The viability of the all-optical modulation approach is demonstrated with an immunoassay detection as a biosensing proof of concept.

Grating couplers integrated on Mach-Zehnder interferometric biosensors operating in the visible range

We present the design, fabrication, and characterization of submicronic grating couplers integrated on Si3N4 rib waveguide Mach-Zehnder interferometers (MZIs) for biosensing applications working in the visible spectral range for both TE and TM polarizations. Depending on the waveguide structure, a maximum of 11.5% of coupling efficiency has been experimentally obtained at 658 nm, while a limit of detection of 1.6 × 10-7 in refractive index unit is achieved for the biosensor. These results represent an important milestone toward the achievement of a truly portable and multiplexed point-of-care platform using the integrated MZI sensor.

Interferometric waveguide biosensors based on Si-technology for point-of-care diagnostic

Silicon photonic biosensors based on evanescent wave detection have revealed themselves as the most promising candidates for achieving truly point-of-care devices as they can overcome the limitations of current analytical techniques. Advantages such as miniaturization, extreme sensitivity, robustness, reliability, potential for multiplexing and mass production at low cost can be offered. Among the existing integrated optical sensors, the interferometric ones are the most attractive due to their extreme sensitivity for label-free and real-time evaluations with detection limits close to 10-7- 10-8 in bulk refractive index. In this article we will review the recent progress in the most common interferometric waveguide biosensors (Mach-Zehnder interferometers, Young interferometers, Hartman interferometers, dual polarization interferometers and bimodal optical waveguides). In particular, we will focus on the description of their optical structures and their applicability for bioanalytical detection.

Silicon photonic biosensors for high innovative point-of-care diagnostic platforms

The application of portable, easy-to-use and highly sensitive biosensor devices for real-time diagnosis could offer significant advantages over current analytical methods. We will describe our last developments in silicon photonic biosensors based on evanescent wave detection, mainly related to the development of portable and highly sensitive integrated photonic sensing platforms.

Multiplexed Integrated Interferometers for Advanced Lab-on-a-Chip Biosensors

We present our last achievements towards the assembly of lab-on-a-chip platforms based on ultrasensitive Mach-Zehnder interferometers. In particular, we will focus on the development of a label-free and real-time multiplexed detection scheme.

Silicon Photonics-based Nanobiosensors for Lab-on-a-chip Integration

We present our work towards the assembly of label-free lab-on-a-chip platforms based on silicon nanointerferometers. The sensors show sensitivity of 10-7 RIU, which means an ability to discern concentrations of biomolecules at pM level.