System-level integration of active silicon photonic biosensors using Fan-Out Wafer-Level-Packaging for low cost and multiplexed point-of-care diagnostic testing

Silicon photonic integrated circuits have gained a lot of attention over the last decade. Although the driving force remains high-speed telecommunications, the same platform has been used to design highly sensitive label-free biosensors. The high refractive index contrast between silicon and silica, or other surrounding media, allows one to build very compact circuits which can be mass produced at low cost by leveraging CMOS foundries. Over the same period, a novel packaging technique, known as Fan-Out Wafer-Level-Packaging (FOWLP), has emerged to address the growing need for miniaturized system-on-a-package chips. Whereas researchers have pushed the limit of detection of photonic sensing devices, system-level integration has received less attention. In this work, we demonstrate the potential of combining silicon photonics with FOWLP to design low-cost multiplexed biosensors. By using on-chip germanium photodetectors, 1 mm(2) dies integrating 16 microring resonators are packaged into epoxy cartridges with electrical interconnects and microfluidic channels. This new architecture reduces the silicon die size while simplifying the microfluidic and optical integration for a more compact and affordable reader device. The biosensors exhibit similar sensitivities as passive circuits. We believe this architecture will pave the way for the commercial deployment of highly multiplexed, yet low-cost point-of-care diagnostic devices.