A Miniature Bio-Photonics Companion Diagnostics Platform for Reliable Cancer Treatment Monitoring in Blood Fluids.

In this paper, we present the development of a photonic biosensor device for cancer treatment monitoring as a complementary diagnostics tool. The proposed device combines multidisciplinary concepts from the photonic, nano-biochemical, micro-fluidic and reader/packaging platforms aiming to overcome limitations related to detection reliability, sensitivity, specificity, compactness and cost issues. The photonic sensor is based on an array of six asymmetric Mach Zender Interferometer (aMZI) waveguides on silicon nitride substrates and the sensing is performed by measuring the phase shift of the output signal, caused by the binding of the analyte on the functionalized aMZI surface. According to the morphological design of the waveguides, an improved sensitivity is achieved in comparison to the current technologies (<5000 nm/RIU). This platform is combined with a novel biofunctionalization methodology that involves material-selective surface chemistries and the high-resolution laser printing of biomaterials resulting in the development of an integrated photonics biosensor device that employs disposable microfluidics cartridges. The device is tested with cancer patient blood serum samples. The detection of periostin (POSTN) and transforming growth factor beta-induced protein (TGFBI), two circulating biomarkers overexpressed by cancer stem cells, is achieved in cancer patient serum with the use of the device.

High performance refractive index sensor based on low Q-factor ring resonators and FFT processing of wavelength scanning data.

We extend our previous simulation study and we present experimental results regarding our Fast Fourier Transform method for the calculation of the resonance shifts in biosensors based on micro-ring resonators (MRRs). For the simulation study, we use a system model with a tunable laser at 850 nm, an MRR with 1.5∙104 quality factor, and a detection system with 50 dB maximum signal-to-noise ratio, and investigate the impact on the system performance of factors like the number of the resonance peaks inside the scanning window, the wavelength dependence of the laser power, and the asymmetry of the transfer functions of the MRRs. We find that the performance is improved by a factor of 2 when we go from single- to four-peak transfer functions, and that the impact of the wavelength dependence of the laser power is very low. We also find that the presence of asymmetries can lead to strong discontinuities of the transfer functions at the edges of the scanning window and can significantly increase the measurement errors, making necessary the use of techniques for their elimination. Using these conclusions, we build a system with sensing MRRs on TriPleX platform, and we experimentally validate our method using sucrose solutions with different concentrations. Involving techniques in order to exclude the noise originating from the microfluidic system, we achieve a wavelength resolution close to 0.08 pm, when the system operates with 0.5 pm scanning step. In combination with the sensitivity of the MRRs, which is measured to be equal to 93.7 nm/RIU, this wavelength resolution indicates the possibility for a limit of detection close to 8.5·10-7 RIU, which represents to the best of our knowledge a record performance for this type of optical sensors and this level of scanning steps.

New set of design rules for resonant refractive index sensors enabled by FFT based processing of the measurement data.

It is still a common belief that ultra-high quality-factors (Q-factors) are a prerequisite in optical resonant cavities for high refractive index resolution and low detection limit in biosensing applications. In combination with the ultra-short steps that are necessary when the measurement of the resonance shift relies on the wavelength scanning of a laser source and conventional methods for data processing, the high Q-factor requirement makes these biosensors extremely impractical. In this work we analyze an alternative processing method based on the fast-Fourier transform, and show through Monte-Carlo simulations that improvement by 2-3 orders of magnitude can be achieved in the resolution and the detection limit of the system in the presence of amplitude and spectral noise. More significantly, this improvement is maximum for low Q-factors around 104 and is present also for high intra-cavity losses and large scanning steps making the designs compatible with the low-cost aspect of lab-on-a-chip technology. Using a micro-ring resonator as model cavity and a system design with low Q-factor (104), low amplitude transmission (0.85) and relatively large scanning step (0.25 pm), we show that resolution close to 0.01 pm and detection limit close to 10-7 RIU can be achieved improving the sensing performance by more than 2 orders of magnitude compared to the performance of systems relying on a simple peak search processing method. The improvement in the limit of detection is present even when the simple method is combined with ultra-high Q-factors and ultra-short scanning steps due to the trade-off between the system resolution and sensitivity. Early experimental results are in agreement with the trends of the numerical studies.

Serial 100 Gb/s connectivity based on polymer photonics and InP-DHBT electronics.

We demonstrate the first integrated transmitter for serial 100 Gb/s NRZ-OOK modulation in datacom and telecom applications. The transmitter relies on the use of an electro-optic polymer modulator and the hybrid integration of an InP laser diode and InP-DHBT electronics with the polymer board. Evaluation is made at 80 and 100 Gb/s through eye-diagrams and BER measurements using a receiver module that integrates a pin-photodiode and an electrical 1:2 demultiplexer. Error-free performance is confirmed both at 80 and 100 Gb/s revealing the viability of the approach and the potential of the technology.

Imaging of Caenorhabditis elegans neurons by second-harmonic generation and two-photon excitation fluorescence.

Second-harmonic generation (SHG) and two-photon excitation fluorescence (TPEF) are relatively new and promising tools for the detailed imaging of biological samples and processes at the microscopic level. By exploiting these nonlinear phenomena phototoxicity and photobleaching effects on the specimens are reduced dramatically. The main target of this work was the development of a compact inexpensive and reliable experimental apparatus for nonlinear microscopy measurements. Femtosecond laser pulses were utilized for excitation. We achieved high-resolution imaging and mapping of Caenorhabditis elegans (C. elegans) neurons and muscular structures of the pharynx, at the microscopic level by performing SHG and TPEF measurements. By detecting nonlinear phenomena such as SHG and TPEF it is feasible to extract valuable information concerning the structure and the function of nematode neurons.