Name: label-free single molecule detection using microtoroid optical resonators
Uploaded: 2015-12-29T14:00:00.000+00:00
Duration: 8 min 53 s
Description: Watch this Scientific Journal Video about Label-free Single Molecule Detection Using Microtoroid Optical Resonators at JoVE.com

This research was supported in part by a National Research Service Award (T32GM07616) from the National Institute of General Medical Sciences.

1. 실험 설정 및 샘플 준비 <ol><li> 리소그래피를 사용하여 에칭하고, 이전에 설명 된 바와 같이 6 과정을 용융 microtoroids를 제작. 일반적으로 80 내지 100 ㎛의 주요 직경, 2 ㎛의 작은 직경을 갖는 실리콘 웨이퍼 (칩)의 상단에 microtoroids를 제작. </li><li> 대략의 섬유 스풀에서 단일 모드 광섬유 (125 μm의 클래딩, 4.3 μm의 모드 필드 직경)의 미터 긴장을 풀고. </li><li> 광섬유의 풀린 부분의 중간에, 와이어 스트리퍼를 사용하여 광 화이버의 주위에 폴리머 코팅재의 작은 세그먼트 (2.5 cm)를 스트립. 주 :이 microtoroid 순간적으로 커플 광에 사용되는 광섬유의 부분이다. </li><li> 이소프로판올 알코올과 무료로 닦아 보풀 제거 섬유를 청소합니다. </li><li> 자기 클램프로 만든 섬유 홀더를 사용하는 대신에 섬유의이 부분을 잡으십시오. </li><li> meltin으로 ~ 500 nm의 얇은 스트립 섬유g 및 수소 토치가 60㎛ / 분에서 서로 반대 방향으로 움직이는 두 개의 스텝퍼 모터를 사용하여 당기는. ~ 10mm 높이 있어야 화염의 상부 내부에 광섬유를 위치. 광섬유를 통해 전송이 (오프 섬유 점멸로부터 측 방향으로 산란되는 광을 보면서)이나 오실로스코프에 연결된 포토 다이오드에 섬유를 연결하여 시각적으로 감시 할 수있는 요동 정지시 섬유 당기는 중지 . </li><li> 광섬유의 한쪽 끝을 절단 및 베어 섬유 어댑터에 삽입합니다. 수광부의 입력에 섬유의 끝을 놓습니다. </li><li> 섬유 커플 광섬유 결합기를 이용하여 레이저 광 스풀의 타단. </li><li> 에폭시 또는 양면 테이프를 사용하여 샘​​플 홀더의 상단에있는 microtoroid 칩 (스테인레스 스틸, 37.8 mm X 6.4 mm X 3.2 mm)를 놓습니다. </li><li> (3 축 나노 포지셔닝 포함하는 위치 결정 스테이지의 상부에 샘플 홀더를 마운트 N3 축 마이크로 미터 위에 anocube) 단계 (장치 목록 참조). 진동을 최소화하기 위해 공압 고립 된 광학 테이블에 모든 실험을 수행합니다. </li><li> 조대 위치 3 축 마이크로 미터를 사용하여 샘​​플 칩. </li><li> 나노 포지셔너를 사용하여 광섬유에 microtoroid 함유 칩과 평행을 맞 춥니 다. 참고 : 입력 광 (~ 633 ㎚)의 한 파장의 거리에 microtoroid을 맞 춥니 다. 이 프로세스의 시각화를위한 두 개의 촬상 컬럼 사용 상단과 칩의 측면 상에 위치 (대물 렌즈 및 카메라를 가진 튜브를 장비 목록 참조). </li><li> 인라인 편광 제어기를 사용하여 광섬유를 통해 지향 레이저 광의 편광을 최적화하는 편광을 조정 노브 (장치 목록 참조). 주 : 광섬유의 전송에서 측정 된 딥 좁은 나타날 때 최적의 편광이 달성된다. 오실로스코프 (자세한 내용은 단계 2.2 참조)이 수영을 관찰한다. </li><li> 구축스페이서로서 유리 현미경 슬라이드를 사용하여 샘​​플 스테이지 위에 유리 커버 슬립을 epoxying 의해 샘플 챔버. 참고 : 전체 설치를 포함하는 플렉시 유리 인클로저는 공기 흐름을 최소화하는 데 유용 할 수 있습니다. 작은 개구는 튜브를 사용하여 펌핑 할 수있는 솔루션을 수 있도록 남아 있어야합니다. </li><li> 열적 RT 수조 (~ 500 ml)에 1 시간 동안 ≥ 입자 현탁액 또는 단일 분자 수용액 평형. 참고 : 시료는 제조 업체, 예를 들어, PBS 또는 HEPES에서 지정한 관련 버퍼를 사용하여 마이크로 원심 튜브에 원하는 농도로 희석한다. 어떠한 바인딩 이벤트가 검출되지 않은 경우, 버퍼의 염 농도를 증가시킨다. </li><li> ~ 2 초 동안 솔루션 (1 ml)을 간략하게 포함 소용돌이 입자. </li><li> 1 mL의 샘플에서 챔버 내로 입자 함유 용액을 주입 / 1ml를 주사기 펌프를 사용하여 민. </li><li> 샘플 챔버가 작성되면, 주사기 펌프의 전원을 끄십시오. </li><li> 기록 데이터를 최소화하기 전에 30 초를 기다립니다측정에 영향을 미칠 수있는 유체의 흐름으로 인한 기계적인 진동의 영향. </li></ol> 2. 주파수 잠금 <ol><li> 커플 링은 유체의 주입으로 인해 방해되기 때문에, 나노 위치로 샘플 홀더를 이동시킴으로써 광섬유에 토 로이드 - 커플 재. </li><li> 다양한 파장 통해 컴퓨터 제어 입력을 레이저 스캐닝하여 microtoroid의 공진 파장을 찾아. 레이저의 파장을 조절하는 레이저 컨트롤러 내의 압전 소자에 삼각파 전압 신호를 전송하여이 단계를 수행한다. 이 파장에서 물에 빛의 낮은 흡수가로 가시 광선 (2.5 nm의 ± 635 나노 미터)를 사용하여 실험을 수행합니다. </li><li> 자동 평형 수광부로 광섬유의 출력을 연결하여 광섬유를 통해 광 투과율을 측정한다. BNC 케이블을 사용하여 오실로스코프에 수광부의 출력을 연결합니다. O 관찰n은 오실로스코프는 microtoroid의 공진 파장에서, 광섬유를 통해 전송 방울있다. </li><li> 케이블을 통해 피드백 컨트롤러 (장비 목록 참조) 고정 주파수의 주요 입력 수광부의 출력을 연결합니다. </li><li> 2 kHz의 디더 주파수와 19 FM의 파장 진동의 진폭과 잠금 최고 수준의 피크를 사용하여 자동 잠금 모드에서 주파수 잠금 피드백 제어를 실행합니다. 경험적으로 지글러 - 니콜스 튜닝 규칙 (14)을 사용하여 소프트웨어 창의 비례 적분 미분 설정을 설정한다. 참고 :이 값은 모든 실험의 시작 부분에 한 번 설정 만하면됩니다. </li><li> microtoroid의 공진 파장 레이저의 파장을 자동 - 잠금. 샘플 챔버를 충전 한 후이 단계를 수행합니다. 주 : 파장 변화가 너무 큰 경우, 피드백 제어기는 잠금을 잃게 자동 공진 파장의 위치를​​ 찾기 위해 스캔 모드로 전환. 이 OC파장에 대한 CURS 약 1 선폭 (여기 조사 모든 시스템에 대해 적어도 600 FM)보다 큰 이동합니다. </li><li> 24 비트 데이터 수집 카드를 사용하여 20 kHz에서 피드백 제어기의 출력을 기록한다. 데이터 수집 소프트웨어를 통해 텍스트 파일로 데이터를 내보낼. </li></ol> 3. 데이터 처리 및 분석 <ol><li> 푸리에 MATLAB에서 데이터를 변환. </li><li> 낮은 2 kHz에서의 부과 디더 주파수를 제거하기 위해 1 kHz에서 컷오프와 &quot;벽돌 벽&quot;필터를 사용하여 데이터를 전달 (보충 코드 스크린 샷 1 파일 참조). </li><li> 계산적 노치는 16 Hz의 윈도우 크기를 사용하여 데이터를 필터링. 참고 :이이 경우에, 소음의 알려진 원인을 제거하기위한 것입니다, 60 Hz의 전자 라인 노이즈 및 고조파 (레이저 드라이버에서 오는)뿐만 아니라 100 Hz에서의 고조파 (보충 코드 스크린 샷 1 파일 참조). </li><li> 역 푸리에 변환은 시간 도메인으로 데이터를 다시 변환. </li><li> 메디안 필터 창을 이용하여 상기 데이터1,001 샘플의 크기 (보충 코드 스크린 샷 2 파일 참조). </li><li> Kerssemakers 등. (15)의 스텝 찾는 알고리즘을 사용하여 공진 파장의 단계 변화를 찾습니다. </li><li> 각 바인딩 단계의 진폭의 히스토그램을 생성합니다. </li><li> 식을 사용하여 입자 크기를 계산한다. (1) (토론 참조). </li></ol>

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The authors declare that they have no competing financial interests.

입자가 결합 된 바와 같이, 환형 상승의 공진 파장 (λ). 입자가 바인딩 해제하면, 공진 파장은 대응 (스텝 - 다운 이벤트)를 감소시킨다. 입자 직경 (d)는 각각의 파장 단계의 진폭 히스토그램을 통해 결정될 수있다. 각 파장 단계의 높이가 결합 입자의 크기 변화로 인해 입자가 결합 microtoroid의 위치로 인해 변한다. 입자는 전기장 (E 0 맥스)이 최대가 microtoroid의 적?...

단일 분자 검출 실험은 질병의 조기 진단을위한 바이오 센서에 사용되는 분석 물의 양을 감소시키는 데 유용하며, 분자 (3)의 기본 특성을 조사하기위한. 이러한 실험은 일반적으로 라벨 그러나, 라벨은 항상 이벤트가 검토되고 교란 수, 비용 증가, 특정 단백질을 얻을 수없고, 특히 현장 실험 또는 포인트 외 실시간 들면 불편할 수있다하여 수행 의료 진단. 라벨없는 바이오 센서에 대한 현재 금 표준 그러나 상업적 표면 플라즈몬 공명 시스템은 전형적 nm 인 검출 순서에 전형적인 하한을 가지고, 표면 플라즈몬 공명 (4)이다. 최근, 광 공진기는 라벨이없는 단일 분자 biodetection 5 유망 기술로 등장했다. 장기 (NS)에 기초하여 광 공진기 일 -6,7-의 광 가둠. 빛은 순간적이다일반적으로, 광섬유를 통해 이러한 장치에 연결된다. 섬유 거치지 광의 파장 공진기의 공진 파장과 일치 할 때, 효율적으로 공진기에 커플 빛. 이 결합 된 광은 완전히 내부 공진기의 둘레 근방에 소 산장을 발생 공진기의 공동 내에 반영한다. 입자는 공진기, 입자 (8)의 체적에 비례하여 변화 공진기의 공진 파장 산장 인드에 진입. 검출 능력의 관점에서, 미세 공진기 이전 단일에게 인플루엔자 바이러스 입자 (100 ㎚) 9,10 검출하는데 사용되어왔다. 최근 plasmonically 향상된 미세 광학 공진기 그러나이 접근법은 드 0.3 μm의 (2)에 입자 포획 영역을 제한하고, 분자 (11) 및 8 량체 올리고 12 알부민 단일 소 혈청을 검출하는데 사용되어왔다바이스. 큰 캡처 영역 바이오 센서는 입자 검출의 가능성을 최대화 이상적이다. 큰 (&gt; 100 μm의 2) 캡쳐 영역과 현재 솔루션 기반의 라벨없는 바이오 센싱 기술은 폴리스티렌 입자를 ≥ 25 nm의 검출에 한정되어있다. 우리는 용액 중의 분자의 단일 시간 - 분해 검출 할 수있는 에바 네 슨트 광 위스퍼 링 공진기 (FLOWER) (13) (도 1)을 잠그기 주파수라고도 광 공진기 기술 기반의 라벨없는 바이오 센싱 시스템을 개발 하였다. FLOWER 주파수 로크 피드백 제어, 평형 검출 한 단일 단백질 분자로 내려 작은 입자를 검출하는 필터링 연산과 결합 microtoroid 광학 공진기의 길이 광자 수명을 이용한다. 주파수 록의 이용은 스위프 또는 레이저 파장을 스캐닝 할 필요없이, 입자 결합으로 시스템이 항상 microtoroid의 이동 공명을 추적 할 수 있도록큰 범위. 꽃의 원리 플라즈몬 강화를 포함하는 다른 기법의 검출 능력을 향상시키기 위해 사용될 수있다. 다음 것에서, FLOWER를 행하는 절차를 설명한다.

<table><tbody><tr><td>Tunable diode laser</td><td>Newport</td><td>TLB-6300</td><td></td></tr><tr><td>Laser controller</td><td>Newport</td><td>TLB-6300-LN</td><td></td></tr><tr><td>Frequency locking feedback controller</td><td>Toptica Photonics</td><td>Digilock 110</td><td></td></tr><tr><td>Auto-balanced photoreceiver</td><td>Newport</td><td>Model 2007</td><td></td></tr><tr><td>In-line polarization controller</td><td>General Photonics</td><td>PLC-003-S-90</td><td></td></tr><tr><td>24-bit data acquisition card</td><td>National Instruments</td><td>NI-PCI-4461</td><td></td></tr><tr><td>Recombinant human interleukin-2</td><td>Pierce Biotechnology</td><td>R201520</td><td></td></tr><tr><td>20 nm polystyrene beads</td><td>Thermo Scientific</td><td>3020A</td><td></td></tr><tr><td>NanoCube XYZ Piezo Stage</td><td>Physik Instrumente</td><td>P-611.3</td><td></td></tr><tr><td>Optical table</td><td>Newport</td><td>VH3660W-OPT</td><td></td></tr><tr><td>Objective lens for imaging column</td><td>Navitar Machine Vision</td><td>1-60228</td><td></td></tr><tr><td>Imaging column (adaptor tube)</td><td>Navitar Machine Vision</td><td>1-60228</td><td></td></tr><tr><td>High-Res CCD camera for imaging column</td><td>Edmund Industrial Optics</td><td>NT39244</td><td></td></tr></tbody></table>

label-free single molecule detection using microtoroid optical resonators

아래로 단일 분자 한계 분자의 작은 농도를 검출하는 것은 이러한 질병의 조기 발견 및 분자의 행동에 기초 연구 등의 분야에 영향을 미친다. 단일 분자 검출 기술은 일반적 그러나, 라벨 비용 및 복잡성을 증가, 항상 사용할 수 없으며, 이벤트가 연구되고있다 교란 형광 태그 또는 양자점과 같은 라벨을 사용한다. 광학 공진기는 라벨의 사용없이 하나의 분자를 검출하는 수단으로서 유망 나왔다. 현재 용액에 비 plasmonically 향상된 베어 광 공진기 장치에 의해 검출 된 가장 작은 입자는 25 nm의 폴리스티렌 구 1이다. 우리는 위스퍼 에바 네 센트 광 공진기 수용액 2 라벨없는 단일 분자 검출이 한계를 능가 달성 (FLOWER)를 잠그기 주파수로 알려진 기술을 개발했다. 신호 강도가 입자 볼륨 확장, 우리의 작품은&gt; 100 배의 양식 개선을 나타냅니다NT 기술의 현재 상태 위에 잡음비 (SNR)에 신호한다. 여기 FLOWER 뒤에 절차 야전에서의 사용을 증가시키기위한 노력으로 제시된다.

이벤트를 결합 입자는 분명히 시간 (그림 2A)를 통해 microtoroid의 공진 파장의 단계와 같은 변화로 볼 수 있습니다. 이러한 단계 높이는.도 2b에 도시 된 바와 같이, 히스토그램은 각각 2-4, 대표 엑소 좀의 결합에서 트레이스 (nanovesicles), 5 nm의 실리카 비드, 및 단일 인간 인터루킨 2 분자를 표시하는 도면이다. 계단 형 이벤트 입경 확장된...

Watch this Scientific Journal Video about Label-free Single Molecule Detection Using Microtoroid Optical Resonators at JoVE.com

Label-free Single Molecule Detection Using Microtoroid Optical Resonators

We have developed a label-free biosensing system based on optical resonator technology known as Frequency Locking Optical Whispering Evanescent Resonator (FLOWER) that is capable of detecting single molecules in solution. Here the procedures behind this work are described and presented.

Microtoroid 광 공진기를 사용하여 라벨이없는 단일 분자 검출

Detecting small concentrations of molecules down to the single molecule limit has impact on areas such as early detection of disease, and fundamental ...

label-free-single-molecule-detection-using-microtoroid-optical

Research

JoVE Journal

Bioengineering

9.2K 조회수.  California Institute of Technology. We have developed a label-free biosensing system based on optical resonator technology known as Frequency Locking Optical Whispering Evanescent Resonator (FLOWER) that is capable of detecting single molecules in solution. Here the procedures behind this work are described and presented. 

비디오: Label-free Single Molecule Detection Using Microtoroid Optical Resonators

Fabrication of Silica Ultra High Quality Factor Microresonators

Whispering gallery resonant cavities confine light in circular orbits at their periphery.1-2 The photon storage lifetime in the cavity, quantified by the quality factor (Q) of the cavity, can be in excess of 500ns for cavities with Q factors above 100 million. As a result of their low material losses, silica microcavities have demonstrated some of the longest photon lifetimes to date1-2. Since a portion of the circulating light extends outside the resonator, these devices can also be used to probe the surroundings. This interaction has enabled numerous experiments in biology, such as single molecule biodetection and antibody-antigen kinetics, as well as discoveries in other fields, such as development of ultra-low-threshold microlasers, characterization of thin films, and cavity quantum electrodynamics studies.3-7
The two primary silica resonant cavity geometries are the microsphere and the microtoroid. Both devices rely on a carbon dioxide laser reflow step to achieve their ultra-high-Q factors (Q&gt;100 million).1-2,8-9 However, there are several notable differences between the two structures. Silica microspheres are free-standing, supported by a single optical fiber, whereas silica microtoroids can be fabricated on a silicon wafer in large arrays using a combination of lithography and etching steps. These differences influence which device is optimal for a given experiment.
Here, we present detailed fabrication protocols for both types of resonant cavities. While the fabrication of microsphere resonant cavities is fairly straightforward, the fabrication of microtoroid resonant cavities requires additional specialized equipment and facilities (cleanroom). Therefore, this additional requirement may also influence which device is selected for a given experiment.
Introduction
An optical resonator efficiently confines light at specific wavelengths, known as the resonant wavelengths of the device. 1-2 The common figure of merit for these optical resonators is the quality factor or Q. This term describes the photon lifetime (&tau;o) within the resonator, which is directly related to the resonator's optical losses. Therefore, an optical resonator with a high Q factor has low optical losses, long photon lifetimes, and very low photon decay rates (1/&tau;o). As a result of the long photon lifetimes, it is possible to build-up extremely large circulating optical field intensities in these devices. This very unique property has allowed these devices to be used as laser sources and integrated biosensors.10
A unique sub-class of resonators is the whispering gallery mode optical microcavity. In these devices, the light is confined in circular orbits at the periphery. Therefore, the field is not completely confined within the device, but evanesces into the environment. Whispering gallery mode optical cavities have demonstrated some of the highest quality factors of any optical resonant cavity to date.9,11 Therefore, these devices are used throughout science and engineering, including in fundamental physics studies and in telecommunications as well as in biodetection experiments. 3-7,12
Optical microcavities can be fabricated from a wide range of materials and in a wide variety of geometries. A few examples include silica and silicon microtoroids, silicon, silicon nitride, and silica microdisks, micropillars, and silica and polymer microrings.13-17 The range in quality factor (Q) varies as dramatically as the geometry. Although both geometry and high Q are important considerations in any field, in many applications, there is far greater leverage in boosting device performance through Q enhancement. Among the numerous options detailed previously, the silica microsphere and the silica microtoroid resonator have achieved some of the highest Q factors to date.1,9 Additionally, as a result of the extremely low optical loss of silica from the visible through the near-IR, both microspheres and microtoroids are able to maintain their Q factors over a wide range of testing wavelengths.18 Finally, because silica is inherently biocompatible, it is routinely used in biodetection experiments.
In addition to high material absorption, there are several other potential loss mechanisms, including surface roughness, radiation loss, and contamination loss.2 Through an optimization of the device size, it is possible to eliminate radiation losses, which arise from poor optical field confinement within the device. Similarly, by storing a device in an appropriately clean environment, contamination of the surface can be minimized. Therefore, in addition to material loss, surface scattering is the primary loss mechanism of concern.2,8
In silica devices, surface scattering is minimized by using a laser reflow technique, which melts the silica through surface tension induced reflow. While spherical optical resonators have been studied for many years, it is only with recent advances in fabrication technologies that researchers been able to fabricate high quality silica optical toroidal microresonators (Q&gt;100 million) on a silicon substrate, thus paving the way for integration with microfluidics.1
The present series of protocols details how to fabricate both silica microsphere and microtoroid resonant cavities. While silica microsphere resonant cavities are well-established, microtoroid resonant cavities were only recently invented.1 As many of the fundamental methods used to fabricate the microsphere are also used in the more complex microtoroid fabrication procedure, by including both in a single protocol it will enable researchers to more easily trouble-shoot their experiments.

We describe the use of a carbon dioxide laser reflow technique to fabricate silica resonant cavities, including free-standing microspheres and on-chip microtoroids. The reflow method removes surface imperfections, allowing long photon lifetimes within both devices. The resulting devices have ultra high quality factors, enabling applications ranging from telecommunications to biodetection.

실리카 초고 품질 팩터 Microresonators의 제작

Whispering gallery resonant cavities confine light in circular orbits at their periphery.1-2 The photon storage lifetime in the cavity, quantified by the ...

연구

공학

Optical Trapping of Nanoparticles

Optical trapping is a technique for immobilizing and manipulating small objects in a gentle way using light, and it has been widely applied in trapping and manipulating small biological particles. Ashkin and co-workers first demonstrated optical tweezers using a single focused beam1. The single beam trap can be described accurately using the perturbative gradient force formulation in the case of small Rayleigh regime particles1. In the perturbative regime, the optical power required for trapping a particle scales as the inverse fourth power of the particle size. High optical powers can damage dielectric particles and cause heating. For instance, trapped latex spheres of 109 nm in diameter were destroyed by a 15 mW beam in 25 sec1, which has serious implications for biological matter2,3.
A self-induced back-action (SIBA) optical trapping was proposed to trap 50 nm polystyrene spheres in the non-perturbative regime4. In a non-perturbative regime, even a small particle with little permittivity contrast to the background can influence significantly the ambient electromagnetic field and induce a large optical force. As a particle enters an illuminated aperture, light transmission increases dramatically because of dielectric loading. If the particle attempts to leave the aperture, decreased transmission causes a change in momentum outwards from the hole and, by Newton's Third Law, results in a force on the particle inwards into the hole, trapping the particle. The light transmission can be monitored; hence, the trap can become a sensor. The SIBA trapping technique can be further improved by using a double-nanohole structure.
The double-nanohole structure has been shown to give a strong local field enhancement5,6. Between the two sharp tips of the double-nanohole, a small particle can cause a large change in optical transmission, thereby inducing a large optical force. As a result, smaller nanoparticles can be trapped, such as 12 nm silicate spheres7 and 3.4 nm hydrodynamic radius bovine serum albumin proteins8. In this work, the experimental configuration used for nanoparticle trapping is outlined. First, we detail the assembly of the trapping setup which is based on a Thorlabs Optical Tweezer Kit. Next, we explain the nanofabrication procedure of the double-nanohole in a metal film, the fabrication of the microfluidic chamber and the sample preparation. Finally, we detail the data acquisition procedure and provide typical results for trapping 20 nm polystyrene nanospheres.

The following setup approach details low power optical trapping of dielectric nanoparticles using a double-nanohole in metal film.

나노 입자의 광학 트래핑

Optical trapping is a technique for immobilizing and manipulating small objects in a gentle way using light, and it has been widely applied in trapping ...

Synthesis and Operation of Fluorescent-core Microcavities for Refractometric Sensing

This paper discusses fluorescent core microcavity-based sensors that can operate in a microfluidic analysis setup. These structures are based on the formation of a fluorescent quantum-dot (QD) coating on the channel surface of a conventional microcapillary. Silicon QDs are especially attractive for this application, owing in part to their negligible toxicity compared to the II-VI and II-VI compound QDs, which are legislatively controlled substances in many countries. While the ensemble emission spectrum is broad and featureless, an Si-QD film on the channel wall of a capillary features a set of sharp, narrow peaks in the fluorescence spectrum, corresponding to the electromagnetic resonances for light trapped within the film. The peak wavelength of these resonances is sensitive to the external medium, thus permitting the device to function as a refractometric sensor in which the QDs never come into physical contact with the analyte. The experimental methods associated with the fabrication of the fluorescent-core microcapillaries are discussed in detail, as well as the analysis methods. Finally, a comparison is made between these structures and the more widely investigated liquid-core optical ring resonators, in terms of microfluidic sensing capabilities.

Fluorescent-core microcavity sensors employ a high-index quantum-dot coating in the channel of silica microcapillaries. Changes in the refractive index of fluids pumped into the capillary channel cause shifts in the microcavity fluorescence spectrum that can be used to analyze the channel medium.

Refractometric 감지 용 형광 코어 Microcavities의 합성 및 운영

This paper discusses  fluorescent core microcavity-based sensors that can operate in a microfluidic  analysis setup. These structures are based on the ...

Implementation of a Reference Interferometer for Nanodetection

A thermally and mechanically stabilized fiber interferometer suited for examining ultra-high quality factor microcavities is fashioned. After assessing its free spectral range (FSR), the module is put in parallel with a fiber taper-microcavity system and then calibrated through isolating and eliminating random shifts in the laser frequency (i.e. laser jitter noise). To realize the taper-microcavity junction and to maximize the optical power that is transferred to the resonator, a single-mode optical fiber waveguide is pulled. Solutions containing polystyrene nanobeads are then prepared and flown to the microcavity in order to demonstrate the system&#8217;s ability to sense binding to the surface of the microcavity. Data is post-processed via adaptive curve fitting, which allows for high-resolution measurements of the quality factor as well as the plotting of time-dependent parameters, such as resonant wavelength and split frequency shifts. By carefully inspecting steps in the time-domain response and shifting in the frequency-domain response, this instrument can quantify discrete binding events.

A reference interferometer technique, which is designed to remove undesirable laser jitter noise for nanodetection, is utilized for probing an ultra-high quality factor microcavity. Instructions for assembly, setup, and data acquisition are provided, alongside the measurement process for specifying the cavity quality factor.

Nanodetection에 대한 참조 간섭계의 구현

A thermally and mechanically stabilized fiber interferometer suited for examining ultra-high quality factor microcavities is fashioned. After assessing ...

Fabrication and Testing of Microfluidic Optomechanical Oscillators

Cavity optomechanics experiments that parametrically couple the phonon modes and photon modes have been investigated in various optical systems including microresonators. However, because of the increased acoustic radiative losses during direct liquid immersion of optomechanical devices, almost all published optomechanical experiments have been performed in solid phase. This paper discusses a recently introduced hollow microfluidic optomechanical resonator. Detailed methodology is provided to fabricate these ultra-high-Q microfluidic resonators, perform optomechanical testing, and measure radiation pressure-driven breathing mode and SBS-driven whispering gallery mode parametric vibrations. By confining liquids inside the capillary resonator, high mechanical- and optical- quality factors are simultaneously maintained.

Parametric optomechanical excitations have recently been experimentally demonstrated in microfluidic optomechanical resonators by means of optical radiation pressure and stimulated Brillouin scattering. This paper describes the fabrication of these microfluidic resonators along with methodologies for generating and verifying optomechanical oscillations.

제작 및 미세 유체 광​​ 기계 발진기의 테스트

Cavity optomechanics experiments that parametrically couple the phonon modes and photon modes have been investigated in various optical systems including ...

Attaching Biological Probes to Silica Optical Biosensors Using Silane Coupling Agents

In order to interface with biological environments, biosensor platforms, such as the popular Biacore system (based on the Surface Plasmon Resonance (SPR) technique), make use of various surface modification techniques, that can, for example, prevent surface fouling, tune the hydrophobicity / hydrophilicity of the surface, adapt to a variety of electronic environments, and most frequently, induce specificity towards a target of interest.1-5 These techniques extend the functionality of otherwise highly sensitive biosensors to real-world applications in complex environments, such as blood, urine, and wastewater analysis.2,6-7 While commercial biosensing platforms, such as Biacore, have well-understood, standard techniques for performing such surface modifications, these techniques have not been translated in a standardized fashion to other label-free biosensing platforms, such as Whispering Gallery Mode (WGM) optical resonators.8-9
WGM optical resonators represent a promising technology for performing label-free detection of a wide variety of species at ultra-low concentrations.6,10-12 The high sensitivity of these platforms is a result of their unique geometric optics: WGM optical resonators confine circulating light at specific, integral resonance frequencies.13 Like the SPR platforms, the optical field is not totally confined to the sensor device, but evanesces; this "evanescent tail" can then interact with species in the surrounding environment. This interaction causes the effective refractive index of the optical field to change, resulting in a slight, but detectable, shift in the resonance frequency of the device. Because the optical field circulates, it can interact many times with the environment, resulting in an inherent amplification of the signal, and very high sensitivities to minor changes in the environment.2,14-15
To perform targeted detection in complex environments, these platforms must be paired with a probe molecule (usually one half of a binding pair, e.g. antibodies / antigens) through surface modification.2 Although WGM optical resonators can be fabricated in several geometries from a variety of material systems, the silica microsphere is the most common. These microspheres are generally fabricated on the end of an optical fiber, which provides a "stem" by which the microspheres can be handled during functionalization and detection experiments. Silica surface chemistries may be applied to attach probe molecules to their surfaces; however, traditional techniques generated for planar substrates are often not adequate for these three-dimensional structures, as any changes to the surface of the microspheres (dust, contamination, surface defects, and uneven coatings) can have severe, negative consequences on their detection capabilities. Here, we demonstrate a facile approach for the surface functionalization of silica microsphere WGM optical resonators using silane coupling agents to bridge the inorganic surface and the biological environment, by attaching biotin to the silica surface.8,16 Although we use silica microsphere WGM resonators as the sensor system in this report, the protocols are general and can be used to functionalize the surface of any silica device with biotin.

Biosensors interface with complex, biological environments and perform targeted detection by combining highly sensitive sensors with highly specific probes attached to the sensor via surface modification. Here, we demonstrate the surface functionalization of silica optical sensors with biotin using silane coupling agents to bridge the sensor and the biological environment.

실란 커플링 에이전트를 사용하여 실리카 광 Biosensors에 생물 학적 프로브를 부착

In order to interface with biological environments, biosensor platforms, such as the popular Biacore system (based on the Surface Plasmon Resonance (SPR) ...

생체공학

Fabrication and Operation of a Nano-Optical Conveyor Belt

The technique of using focused laser beams to trap and exert forces on small particles has enabled many pivotal discoveries in the nanoscale biological and physical sciences over the past few decades. The progress made in this field invites further study of even smaller systems and at a larger scale, with tools that could be distributed more easily and made more widely available. Unfortunately, the fundamental laws of diffraction limit the minimum size of the focal spot of a laser beam, which makes particles smaller than a half-wavelength in diameter hard to trap and generally prevents an operator from discriminating between particles which are closer together than one half-wavelength. This precludes the optical manipulation of many closely-spaced nanoparticles and&#160;limits the&#160;resolution of optical-mechanical systems. Furthermore, manipulation using focused beams requires beam-forming or steering optics, which can be very bulky and expensive. To address these limitations in the system scalability of conventional optical trapping our lab has devised an alternative technique which utilizes near-field optics to move particles across a chip. Instead of focusing laser beams in the far-field, the optical near field of plasmonic resonators produces the necessary local optical intensity enhancement to overcome the restrictions of diffraction and manipulate particles at higher resolution. Closely-spaced resonators produce strong optical traps which can be addressed to mediate the hand-off of particles from one to the next in a conveyor-belt-like fashion. Here, we describe how to design and produce a conveyor belt using a gold surface patterned with plasmonic C-shaped resonators and how to operate it with polarized laser light to achieve super-resolution nanoparticle manipulation and transport. The nano-optical conveyor belt chip can be produced using lithography techniques and easily packaged and distributed.

The scalability and resolution of conventional optical manipulation techniques are limited by diffraction. We circumvent the diffraction limit and describe a method of optically transporting nanoparticles across a chip using a gold surface patterned with a path of closely spaced C-shaped plasmonic resonators.

나노 광학 컨베이어 벨트의 제작 및 운영

The technique of using focused laser beams to trap and exert forces on small particles has enabled many pivotal discoveries in the nanoscale biological ...

Multicolor Fluorescence Detection for Droplet Microfluidics Using Optical Fibers

Fluorescence assays are the most common readouts used in droplet microfluidics due to their bright signals and fast time response. Applications such as multiplex assays, enzyme evolution, and molecular biology enhanced cell sorting require the detection of two or more colors of fluorescence. Standard multicolor detection systems that couple free space lasers to epifluorescence microscopes are bulky, expensive, and difficult to maintain. In this paper, we describe a scheme to perform multicolor detection by exciting discrete regions of a microfluidic channel with lasers coupled to optical fibers. Emitted light is collected by an optical fiber coupled to a single photodetector. Because the excitation occurs at different spatial locations, the identity of emitted light can be encoded as a temporal shift, eliminating the need for more complicated light filtering schemes. The system has been used to detect droplet populations containing four unique combinations of dyes and to detect sub-nanomolar concentrations of fluorescein.

Multicolor fluorescence detection in droplet microfluidics typically involves bulky and complex epifluorescence microscope-based detection systems. Here we describe a compact and modular multicolor detection scheme that utilizes an array of optical fibers to temporally encode multicolor data collected by a single photodetector.

물방울 미세 유체에 대한 여러 가지 빛깔의 형광 검출 광학 섬유를 사용하여

Fluorescence assays are the most common readouts used in droplet microfluidics due to their bright signals and fast time response. Applications such as ...

Use of Dual Optical Tweezers and Microfluidics for Single-Molecule Studies

Visual biochemistry is a powerful technique for observing the stochastic properties of single enzymes or enzyme complexes that are obscured in the averaging that takes place in bulk-phase studies. To achieve visualization, dual optical tweezers, where one trap is fixed and the other is mobile, are focused into one channel of a multi-stream microfluidic chamber positioned on the stage of an inverted fluorescence microscope. The optical tweezers trap single molecules of fluorescently labeled DNA and fluid flow through the chamber and past the trapped beads, stretches the DNA to B-form (under minimal force, i.e., 0 pN) with the nucleic acid being observed as a white string against a black background. DNA molecules are moved from one stream to the next, by translating the stage perpendicular to the flow to enable the initiation of reactions in a controlled manner. To achieve success, microfluidic devices with optically clear channels are mated to glass syringes held in place in a syringe pump. Optimal results use connectors permanently bonded to the flow cell, tubing that is mechanically rigid and chemically resistant, and which is connected to switching valves that eliminate bubbles that prohibit laminar flow.

Visual, single-molecule biochemistry studied through microfluidic chambers is greatly facilitated using glass barrel, gas-tight syringes, stable connections of tubing to flow cells, and elimination of bubbles by placing switching valves between the syringes and tubing. The protocol describes dual optical traps that enable visualization of DNA transactions and intermolecular interactions.

단일 분자 연구를 위한 이중 광학 핀셋 및 미세 유체 공학 사용

Visual biochemistry is a powerful technique for observing the stochastic properties of single enzymes or enzyme complexes that are obscured in the ...

생화학

Optical Biosensing

Optical biosensors utilize light to detect the binding of a target molecule. These sensors can utilize a label molecule, which produces a measurable signal such as fluorescence,&#160;or these sensors can be label-free&#160;and use the changes in optical properties, such as refractive index, to sense for the binding of the target molecule. This video introduces both label and label-free optical biosensors, demonstrates their use in the laboratory, and shows some applications of the technology.

Types of Optical Biosensing; Surface Plasmon Resonance SPR

Optical biosensors utilize light to detect the binding of a target molecule. These sensors can utilize a label molecule, which produces a measurable signal such as fluorescence, or these sensors can be label-free&#160;and use the changes in optical properties, such as refractive index, to sense for the binding of the target molecule. This video introduces both label and label-free optical biosensors, demonstrates their use in the laboratory, and shows some applications of the technology.

광학 바이오센싱

Optical biosensors utilize light to detect the binding of a target molecule. These sensors can utilize a label molecule, which produces a measurable ...

Microtoroid 광 공진기를 사용하여 라벨이없는 단일 분자 검출

요약

더 많은 비디오 탐색

이 비디오의 챕터

실리카 초고 품질 팩터 Microresonators의 제작

나노 입자의 광학 트래핑

Refractometric 감지 용 형광 코어 Microcavities의 합성 및 운영

Nanodetection에 대한 참조 간섭계의 구현

제작 및 미세 유체 광 기계 발진기의 테스트

실란 커플링 에이전트를 사용하여 실리카 광 Biosensors에 생물 학적 프로브를 부착

나노 광학 컨베이어 벨트의 제작 및 운영

물방울 미세 유체에 대한 여러 가지 빛깔의 형광 검출 광학 섬유를 사용하여

단일 분자 연구를 위한 이중 광학 핀셋 및 미세 유체 공학 사용

광학 바이오센싱

Microtoroid 광 공진기를 사용하여 라벨이없는 단일 분자 검출

요약

더 많은 비디오 탐색

이 비디오의 챕터

실리카 초고 품질 팩터 Microresonators의 제작

나노 입자의 광학 트래핑

Refractometric 감지 용 형광 코어 Microcavities의 합성 및 운영

Nanodetection에 대한 참조 간섭계의 구현

제작 및 미세 유체 광​​ 기계 발진기의 테스트

실란 커플링 에이전트를 사용하여 실리카 광 Biosensors에 생물 학적 프로브를 부착

나노 광학 컨베이어 벨트의 제작 및 운영

물방울 미세 유체에 대한 여러 가지 빛깔의 형광 검출 광학 섬유를 사용하여

단일 분자 연구를 위한 이중 광학 핀셋 및 미세 유체 공학 사용

광학 바이오센싱

제작 및 미세 유체 광 기계 발진기의 테스트