Application areas
Transparency and low loss propagation in the visible and NIR regions make Silicon Nitride (SiN) platforms attractive for many biophotonic sensing and imaging applications. As these areas usually rely on expensive, complicated and often bulky equipment, integrated photonics can bring here cost reduction via possibility of mass-production, significant decrease of equipment size and simplification of maintenance procedures due to integration of all-in-one. Possibility to have dense integration of waveguiding structures on a chip provides an opportunity for high-throughput sensing and imaging of several samples simultaneously, while customer-adapted geometry leads to compatibility with different setup configurations and possibility of integration of those chips as a part of more sophisticated devices. Moreover, all-optical filtering and signal processing opportunities as well as a chance to combine everything with microfluidic parts could allow new generation of fully integrated lab-on-chip devices. LIGENTEC’s AN150 process, optimized for a visible range, transfers our expertise to broad spectrum of new applications related to Life-science Technologies and Biomedical research. With specially provided Process Design Kit (PDK), one can develop and optimize a chip design to fulfill particular requirements and needs, while our experts will assist you with insights on how to achieve the best possible performance.
Biosensing
Integrated photonics based sensing relies on a change of a device’s optical properties while being in contact with the analyte. Schemes of detection can vary from simple waveguides to usage of high-Q ring resonators. In both cases interaction with an analyte is done via evanescent field tail of the mode propagating in a structure; therefore, a waveguide core is usually functionalized to be able to catch the molecules of interest and then is exposed to an environment. Any further binding event slightly changes the refractive index and influences the propagation of light in a way that can be detected. An advantage of the approach is being label-free and compatible with both liquid- or gas-based environments.
One of the most developed methods uses ring resonators as the main sensing component. Here, change in a binded analyte concentration alters the refractive index, which in turn causes a shift in a resonant frequency. High quality resonators, where LIGENTEC has a proven track record, can lead to nanomolar (nM) or even picomolar (pM) detection limit and high sensitivity. Moreover, resonator-based methods have a good fabrication tolerance, providing good results reproducibility for devices of the same design, and are shown to have good regeneration capabilities.
Other bio-sensing methods enabled by integrated photonics approach could also employ MZI-based interferometric schemes, multimode-waveguides interference and different types of label-based techniques, all available with Silicon Nitride platforms.
Biomicroscopy
In bio-related imaging, the visible and near-IR spectral range is mainly used which limits the resolution to the order of several hundred nanometers due to diffraction, making it hard to impossible for a wide-field microscopy to distinguish structures of interest which are significantly smaller than that. To overcome this limitation, several techniques are available, which are generally referred as methods of super-resolution microscopy (or nanoscopy). These methods utilize image post processing to precisely localize the position of each marker and generally set some additional requirements for illumination. To date, the realization of them requires supplementary components and additional imaging steps, which lead to complex, expensive and bulky imaging systems. On-chip waveguides are prominent alternative option to realize required illumination pattern: uniform large-area TIRF illumination with specified field penetration depth can be achieved. In this approach, waveguides serve as a source of evanescent field to excite markers in a sample, which is placed on top of them.
With high power coupling efficiency and low propagation losses enabled by LIGENTEC’s Silicon Nitride platforms, it’s not only possible to obtain simple fluorescence based and TIRF-microscopy images, but to realize advanced methods such as DNA-PAINT, ESI, dSTORM, etc. with a large field-of-view (hundreds of microns diagonal) and demonstrated resolution down to tens of nanometers. Our Multi Project Wafer (MPW) runs provide an opportunity for decreased cost optimization of your designs and user-adapted chip geometry to ensure compatibility with a particular setup and experiment.
A good addition to this are integrated laser beam combiners (ILBC) which allow combination of light collected from several different sources into one fiber/waveguide and therefore simplifies multiwavelength imaging procedure. Here, the beneficial features of Silicon Nitride as a material of choice are its transparency over a broad range of wavelengths, low nonlinearity, permitting high optical power transmission without undesired effects, and good thermal and mechanical stability.
Other emerging applications
The possibility to integrate splitters, multiplexers, highly efficient couplers, spectrally selective elements, customized and controllable output beam spot sizes as well as low losses in a visible and NIR/MIR range opens large perspectives for size and cost reduction in many life-science and biomedical applications varying from Optical Coherence Tomography (OCT), where the whole interferometric part could be integrated on a chip, to Spectrometers and compact Flow-cytometers for live cell sorting using microfluidics. In such devices, integration allows to overcome inefficiencies induced by relative movements and additional interconnects present in their discrete-components counterparts and makes systems more sustainable to perturbations.
The LIGENTEC’s PDK includes a variety of widely-used building blocks to allow effortless design of photonic integrated circuits (PICs) with even high degree of complexity. Combined with our expertise in fabrication of sophisticated circuits and optimized Silicon Nitride platforms for operation in a visible and NIR/MIR range, it becomes one of the best options for development of novel high-performance devices in the area.
Ready to bring your diagnostic platform to market? Contact us to discuss your application — from first prototype to volume production.