Jayson L. Briscoe

A periodically coupled plasmon nanostructure for refractive index sensing.

We present unique characteristics of subwavelength surface plasmon polaritons in a periodically coupled nanowell structure. The nanowell structure offers high quality internal surface plasmon resonance for sensing applications. Calculated FWHM of the transmission peak is 6 nm and the optical transmission is close to 100% at the resonant wavelength of 815.8 nm. The highly concentrated polaritons in the nanowell are sensitive to surface changes providing a sensitivity of 4800% RIU(-1) for optical sensing applications.

Label-Free Plasmonic Immunosensing for Plasmodium in a Whole Blood Lysate

In this paper, we report an experimental demonstration of malaria pathogen detection in a whole blood lysate using plasmonic nanostructures. The plasmon sensor utilizes extraordinary optical transmission through a nanostructure to directly probe antibody-antigen interactions. The measured refractive index sensitivity of the nanostructured sensor is 378 nm per refractive index unit in the visible range. The surface chemistry reported here provides highly site directed and stable antibody immobilization. To validate the observed response of the optical sensor, positive and negative control tests were performed. Results confirm that a refractive index change induced by the interaction between immobilized antibodies and malaria parasites is successfully detected by the fabricated sensor. The demonstrated plasmonic sensor is a compact, highly sensitive, cost effective, selective diagnostic tool for many portable biosensing applications, such as point-of-care diagnostics.

Surface-plasmon-polariton assisted modification of spontaneous emission of colloidal quantum dots in metal nanostructures

We experimentally demonstrate extraordinary optical transmission (EOT) assisted photoluminescence (PL) of CdSe/CdS colloidal quantum dots (QDs). The quantum dots were encapsulated between a metallic nanostructure and a Bragg reflector to enhance the interaction of spontaneously emitted photons with a resonant electromagnetic surface wave. The measured PL spectrum of the fabricated sample exhibits spectral narrowing and a shift in peak wavelength of 22 nm and 7 nm, respectively. Furthermore, we tested the angular dependence of the signal to confirm the existence of EOT. This demonstration is a critical step towards realizing plasmonic colloidal QD based coherent emitters.

Defect-assisted plasmonic crystal sensor.

We demonstrate enhanced sensitivity of a nanostructured plasmonic sensor that utilizes resonance in intentional structural defects within a plasmonic crystal. The measured sensitivity of the fabricated nanosensor is ~500 nm/RIU showing improvement over traditional nanohole array sensors. Furthermore, the defects provide an additional design parameter to increase sensitivity by engineering plasmon lifetime.

Label-free plasmonic immunosensing for plasmodium in whole blood

We present the first experimental demonstration of label-free malaria pathogen detection in whole blood lysate using plasmon nanostructures. Previous studies on plasmonic biosensing have measured antibody-antigen binding, proteinprotein interactions, and detection of bacteria. However, unlike our sensor, many of these works rely on complex optical setups to excite surface plasmon waves. The demonstrated plasmon sensor is a compact, highly sensitive, cost effective, selective diagnostic tool for many portable biosensing applications such as point-of-care diagnostics. To achieve malaria pathogen detection, we utilized a highly site-directed and stable antibody immobilization process on the nanostructures surface. The measured refractive index sensitivity of the nanostructured sensor is 378 nm/RIU in the visible range.

Part-Per-Trillion Level Detection of Microcystin-LR Using a Periodic Nanostructure

Accelerated eutrophication of surface water sources has resulted in an increased presence of cyanobacterial blooms in fresh water. The release of hepatotoxins like microcystins from such blooms can have a catastrophic impact on local human and wildlife ecosystems. Therefore, a rapid, low-cost, reliable, and highly sensitive method for low-concentration detection of microcystins is needed to minimize risks to public health. In this paper, we report the first experimental demonstration of microcystin-leucine-arginine (MC-LR) detection in water at low part-per-trillion levels using a portable optical sensor. The demonstrated biosensor utilizes a highly sensitive electromagnetic surface wave in periodically coupled artificial nanostructures to directly probe the interaction between immobilized antibodies and MC-LR. The surface customization reported here uses a layer-by-layer polyelectrolyte adsorption process to provide highly stable and site-directed immobilization of target antibodies. Steady-state analysis of the sensors response confirms that the plasmonic sensor can detect the presence of MC-LR antigens at part-per-trillion levels. The demonstrated sensor is an important first step toward realizing a lab-on-a-chip sensing system for in situ, autonomous, real-time, distributed environmental monitoring of MC levels in drinking water.

Low level detection of microcystin using a plasmonic biosensor

The presence of cyanobacterial blooms in fresh water has increased due to the accelerated eutrophication of surface water sources. Catastrophic impact to local human and wildlife ecosystems from blooms is linked to the release of hepatotoxins, such as microcystins, into fresh water sources. Therefore, a low-cost, reliable, and highly sensitive method for low concentration detection of microcystins is vitally important to minimize public health risks. In this paper, we report on the first experimental demonstration of microcystins-LR (MC-LR) at low part-per-trillion levels. The demonstrated sensor uses periodically coupled artificial nanostructures to excite a highly sensitive electromagnetic surface wave which directly probes interactions between immobilized antibodies and MC-LR. A layer-by-layer polyelectrolyte adsorption process is utilized to provide highly stable and site-directed immobilization of target antibodies. Steady-state response of the fabricated biosensor confirms detection of MC-LR antigens at low part-per-trillion concentration levels. This demonstration is an important first step towards the development of a lab-on-a-chip sensing systems for in-situ, real-time, distributed environmental monitoring of MC-LR levels in drinking water.

Defect-assisted plasmonic sensing

We report on a new class of plasmonic nanosensor which combines extraordinary optical transmission and resonance within structural defects in a plasmonic crystal. Resonant modes within the defect increase plasmon wave lifetime leading to enhanced light-analyte interactions. Initial sensitivity characterization was performed and simple linear regression analysis determines sensitivity to be 501nm·RIU-1, showing improvement over traditional nanohole array sensors.

Enhanced sensitivity in periodically coupled antenna sensors

The authors report on an experimental demonstration of sensitivity enhancement in periodically coupled bowtie aperture antenna sensors. Periodic metal nanostructures have been widely used in chemical and biosensing because of their high sensitivity to the surrounding dielectric environment. The demonstrated sensor exploits the near-field enhancement in a bowtie aperture antenna to increase refractive index sensitivity. A conventional nanohole array and a bowtie aperture antenna array were fabricated and experimentally characterized. The measured refractive index sensitivity values of the nanohole array and the antenna array are 410nm/RIU and 628nm/RIU, respectively. This demonstration is an important step towards the development of highly sensitive lab-on-a-chip sensing systems.