On-a-chip biosensing based on all-dielectric nanoresonators

📝 Abstract

Nanophotonics has become a key enabling technology in biomedicine with great promises in early diagnosis and less invasive therapies. In this context, the unique capability of plasmonic noble metal nanoparticles to concentrate light on the nanometer scale has widely contributed to biosensing and enhanced spectroscopy. Recently, high-refractive index dielectric nanostructures featuring low loss resonances have been proposed as a promising alternative to nanoplasmonics, potentially offering better sensing performances along with full compatibility with the microelectronics industry. In this letter we report the first demonstration of biosensing with silicon nanoresonators integrated in state-of-the-art microfluidics. Our lab-on-a-chip platform enables detecting Prostate Specific Antigen (PSA) cancer marker in human serum with a sensitivity that meets clinical needs. These performances are directly compared with its plasmonic counterpart based on gold nanorods. Our work opens new opportunities in the development of future point-of-care devices towards a more personalized healthcare.

💡 Analysis

Nanophotonics has become a key enabling technology in biomedicine with great promises in early diagnosis and less invasive therapies. In this context, the unique capability of plasmonic noble metal nanoparticles to concentrate light on the nanometer scale has widely contributed to biosensing and enhanced spectroscopy. Recently, high-refractive index dielectric nanostructures featuring low loss resonances have been proposed as a promising alternative to nanoplasmonics, potentially offering better sensing performances along with full compatibility with the microelectronics industry. In this letter we report the first demonstration of biosensing with silicon nanoresonators integrated in state-of-the-art microfluidics. Our lab-on-a-chip platform enables detecting Prostate Specific Antigen (PSA) cancer marker in human serum with a sensitivity that meets clinical needs. These performances are directly compared with its plasmonic counterpart based on gold nanorods. Our work opens new opportunities in the development of future point-of-care devices towards a more personalized healthcare.

📄 Content

On-a-chip biosensing based on all-dielectric nanoresonators
Ozlem Yavas1, Mikael Svedendahl1, Paulina Dobosz1, Vanesa Sanz1, and Romain Quidant1,2 1 ICFO-Institut de Ciencies Fotoniques, Barcelona Institute of Science and Technology, 08860 Castelldefels (Barcelona), Spain 2 ICREA–Institució Catalana de Recerca i Estudis Avançats, 08010 Barcelona, Spain Nanophotonics has become a key enabling technology in biomedicine with great promises in early diagnosis and less invasive therapies. In this context, the unique capability of plasmonic noble metal nanoparticles to concentrate light on the nanometer scale has widely contributed to biosensing and enhanced spectroscopy. Recently, high-refractive index dielectric nanostructures featuring low loss resonances have been proposed as a promising alternative to nanoplasmonics, potentially offering better sensing performances along with full compatibility with the microelectronics industry. In this letter we report the first demonstration of biosensing with silicon nanoresonators integrated in state-of-the-art microfluidics. Our lab-on-a-chip platform enables detecting Prostate Specific Antigen (PSA) cancer marker in human serum with a sensitivity that meets clinical needs. These performances are directly compared with its plasmonic counterpart based on gold nanorods. Our work opens new opportunities in the development of future point-of-care devices towards a more personalized healthcare. Keywords: lab-on-chip, all-dielectric nanoresonators, biosensing, cancer, silicon

The need for point-of-care devices in health and wellness monitoring is one of the principal motivations behind the current development in biosensing. Among the different available transduction schemes, optical biosensors hold the advantage of being highly sensitive, enabling label free and cost effective real time sensing1. Beyond silicon-based integrated optics2–4 that shows great promises for sensing, surface plasmon resonance (SPR)5–8 and fiber optics9,10 based sensors utilizing propagating evanescent waves have been extensively studied and validated on a wide range of analytes. However, coupling incoming light to the surface modes usually requires sophisticated optics and such sensors are often limited to large bioanalytes, owing to a substantial spatial mismatch of the sensing mode with the tiniest molecules. These limitations can partially be overcome by using 3D nano-optical resonators. In particular, extensive efforts have been put on localized surface plasmon resonance (LSPR) sensors11–13 which exploit the unique properties of noble metal nanoantennas. The ability to excite LSPR with freely propagating incident light considerably simplifies the optical setup needed for such label free measurements. Highly confined modes also provide strong overlap between the electromagnetic field on the surface and the relevant biological analyte dimensions. Finally, the tiny size of each nanosensors enable their assembly in small foot print sensing areas compatible with parallel multi-detection platforms11–13. However, plasmonic nanoparticles suffer from dissipative losses in the metal that lead to broad resonances that eventually limit the sensitivity of the sensor read-out. Recently, high refractive index dielectric nanoparticles have been proposed as an attractive alternative to plasmonic nanoparticles in wide range of applications.14,15
All-dielectric nanophotonics is a fast progressing field which enables manipulation of both electric and magnetic components of the incoming light. These unique properties open up new opportunities in the field of metamaterials including negative refractive index, cloaking, superlensing and many more.15–20 In practice, light coupling to dielectric subwavelength particles results in the excitation of both magnetic and electric multipole resonances which translates into multiple peaks in their extinction spectrum. Similar to metallic nanoparticles, the resonance frequencies depend on their geometry, constitutive material and the dielectric environment. Their sensitivity to the surrounding dielectric permittivity along with their strong mode localization suggests high index dielectric nanoparticles could perform well as biosensing transducers.14,21–23 Silicon nanoresonators, with resonances in visible-NIR spectral range, were first studied theoretically and more recently measured experimentally24–28. The use of silicon is motivated by its compatibility with the microelectronics industry, high material abundance and low cost. While it has recently been suggested that Si nanoresonators could benefit to the detection of biological molecules, so far, only bulk refractive index sensing measurements have been reported.21–23 In this letter, we demonstrate that Si nanoresonator arrays integrated with state-of-the-art microfluidics result in an efficient sensing platform for the detection of protein cancer markers in hu

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