Integrated bimodal waveguide interferometric biosensor for label-free analysis

The performance of an interferometric device based on integrated Bimodal Waveguides (BiMW) for sensing is demonstrated. The sensors are fabricated using standard silicon technology and can achieve a detection limit of 2.5 · 10 RIU for homogeneous sensing, rendering in a very high sensitive device. The applicability of the bimodal waveguide interferometer as label-free biosensor has been demonstrated by the real-time monitoring of the biomolecular interaction of BSA and antiBSA. Due to their simplicity, the interferometric devices could be further integrated in complete lab-on-a-chip platforms for point-of-care diagnostics showing them as a powerful instrument for biochemical analysis

Nanophotonic lab-on-a-chip platforms including novel bimodal interferometers, microfluidics and grating couplers

One of the main limitations for achieving truly lab-on-a-chip (LOC) devices for point-of-care diagnosis is the incorporation of the "on-chip" detection. Indeed, most of the state-of-the-art LOC devices usually require complex read-out instrumentation, losing the main advantages of portability and simplicity. In this context, we present our last advances towards the achievement of a portable and label-free LOC platform with highly sensitive "on-chip" detection by using nanophotonic biosensors. Bimodal waveguide interferometers fabricated by standard silicon processes have been integrated with sub-micronic grating couplers for efficient light in-coupling, showing a phase resolution of 6.6 × 10 × 2π rad and a limit of detection of 3.3 × 10 refractive index unit (RIU) in bulk. A 3D network of SU-8 polymer microfluidics monolithically assembled at the wafer-level was included, ensuring perfect sealing and compact packaging. To overcome some of the drawbacks inherent to interferometric read-outs, a novel all-optical wavelength modulation system has been implemented, providing a linear response and a direct read-out of the phase variation. Sensitivity, specificity and reproducibility of the wavelength modulated BiMW sensor has been demonstrated through the label-free immunodetection of the human hormone hTSH at picomolar level using a reliable biofunctionalization process

Silicon photonic biosensors for lab-on-a-chip applications

In the last two decades, we have witnessed a remarkable progress in the development of biosensor devices and their application in areas such as environmental monitoring, biotechnology, medical diagnostics, drug screening, food safety, and security, among others. The technology of optical biosensors has reached a high degree of maturity and several commercial products are on the market. But problems of stability, sensitivity, and size have prevented the general use of optical biosensors for real field applications. Integrated photonic biosensors based on silicon technology could solve such drawbacks, offering early diagnostic tools with better sensitivity, specificity, and reliability, which could improve the effectiveness of in-vivo and in-vitro diagnostics. Our last developments in silicon photonic biosensors will be showed, mainly related to the development of portable and highly sensitive integrated photonic sensing platforms

Tactile device based on opto-mechanical actuation of liquid crystal elastomers

Nematic elastomers are promising materials for the fabrication of actuators due to their ability to reversibly contract and expand during phase transitions triggered by external stimuli. Thus, actuation can be produced on demand, forcing these phase changes. Here, we present a refreshable tactile device based on the opto-mechanical properties of liquid crystalline elastomers (LCE) with the capability to represent Braille characters and simplified graphical information. The actuators designed are based on the use of the stress gradient generated in the elastomer under illumination to exert a force on movable components. Additionally, hardware implementation and a communication software interface were developed to provide end users with a complete solution. Displacements of 0.8 mm with measured forces of up to 40 mN were reached without material degradation, proving not only the viability of the device but also the potential applications of this type of actuator.Scopu

Nematic opto-mechanical actuators for the fabrication of refreshable tactile systems

Nematic elastomers are promising materials for the fabrication of actuators due to their ability to reversibly contract and expand during phase transitions triggered by external stimuli. We present a refreshable tactile system based on the opto-mechanical properties of liquid-crystalline elastomers (LCE) composites, with the capability to represent Braille characters and graphic information. The actuators designed are based on the stress gradient generated in the elastomer under illumination to exert a force on movable components. Hardware implementation and communication software interface were developed too to provide end users with a complete solution. First tests prove not only the viability of the device, but also the potential applications of this type of actuators.Scopu