Name: optical trap loading of dielectric microparticles in air
Uploaded: 2017-02-05T13:00:00
Description: Watch this Scientific Journal Video about Optical Trap Loading of Dielectric Microparticles In Air at JoVE.com

All work performed under the support of the National Institute of Standards and Technology. Certain commercial equipment, instruments, or materials are identified to foster understanding of this protocol. Such identification does not imply recommendation or endorsement by the National Institute of Standards and Technology, nor does it imply that the materials or equipment identified are necessarily the best available for the purpose.

Dikkat: deneyden önce ilgili tüm güvenlik programları danışın. Bu protokol açıklanan tüm deneysel prosedürleri NIST LASER güvenlik programının yanı sıra diğer ilgili mevzuata uygun olarak yapılır. seçmek ve belirli dalga boyu ve gücü için tasarlanmış lazer koruma gözlük gibi uygun kişisel koruyucu ekipman (PPE) giymek emin olun. Kuru nano / mikro parçacıkları Taşıma ek solunum koruması gerekebilir. 1. Tasarım ve PZT sahibi İmalat ve bir örnek Muhafaza <...

<ol>
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piezoelektrik başlatıcısı Seçilen PZT dinamik performansını optimize etmek için tasarlanmıştır. PZT malzeme ve ultrasonik titreşimlerin yönetiminin doğru seçimi başarılı bir deney verim önemli adımlardır. PZTs farklı özelliklere dönüştürücünün tipine bağlı olarak (toplu olarak veya yığın) ve onu oluşturan malzemeler (sert veya yumuşak) bulunur. sert piezoelektrik malzemeden imal edilmiş bir yığın tipi PZT aşağıdaki nedenlerle tercih edilir. İlk olarak, sert piezoelektrik malz...

Ashkin fizik ve biyofizik temel çalışmalar için birincil araç olarak optik yakalama tekniklerinin geliştirilmesi teşvik 1970 1 romanı başarıda hızlanma ve radyasyon basıncı ile mikropartiküllerin yakalama bildirdi. Bugüne kadar, 2, 3, 4, 5, optik yakalama uygulama, sıvı ortamlarda esas olarak odaklanmıştır, tek biyomoleküllerin mekanik özellikleri koloitlerin davranışından, sistemler çok geniş bir çalışma için kullanılmıştır. 6, 7, gaz ortama optik yakalama 8 Uygulama Bununla birlikte, birçok yeni teknik sorunları çözmek gerekir. Son zamanlarda, hava / vakum optik yakalama giderek temel araştırma uygulanmıştır. Optik levi yanatation potansiyel optik levitated parçacık, küçük nesnelerin 4 ölçüm yüksek frekanslı yerçekimsel dalgalar, 9 kuantum zemin durumlarını inceleyerek ve fraksiyonel ücret karşılığında aramak için ideal bir laboratuvar haline gelir, çevreye bir sistemin neredeyse tamamlama izolasyonu sağlar. 10 Üstelik, hava / vakum düşük viskoziteli biri Brown parçacığın 11 anlık hızını ölçmek için ataleti kullanmak ve doğrusal yay gibi rejimin ötesinde hareket geniş bir yelpazede üzerinde balistik hareket oluşturmanıza olanak sağlar. 12 Bu nedenle, detaylı teknik bilgi ve gaz medyada optik tuzakları uygulamalar geniş bir araştırma topluluğuna daha değerli hale gelmiştir. Yeni deneysel teknikler gaz medyada optik tuzaklar içine nano / mikro parçacıkları yüklemek için gereklidir. Bir piezoelektrik transdüser (PZT), elektro dönüştüren bir cihaz,Mekanik-akustik enerjiye ic enerji, optik havalanma ilk gösterisinden bu yana hava / vakum 5 12 optik tuzaklar içine küçük parçacıkların teslim etmek için kullanılır olmuştur. 1 O zamandan beri, çeşitli yükleme teknikleri, ticari bir püskürtücü 13 veya akustik dalga üreteci tarafından üretilen uçucu aerosoller kullanarak daha küçük parçacıklar yüklemek için ileri sürülmüştür. 14 katı kapanımlar (partiküller) ile yüzen aerosoller rastgele odak yakın geçmek ve tesadüfen tutulur. Aerosol tuzak sonra, çözücü dışarı buharlaşır ve parçacık optik tuzak kalır. Ancak, bu yöntemler de, bir numune içinde istenen parçacıkları tanımlamak seçilen bir parçacık yüklemek ve tuzak salınan eğer onun değişiklikleri izlemek için uygun değildir. Bu protokol deney dahil havada seçici optik tuzak yükleme, yeni uygulayıcılara ayrıntıları sağlamayı amaçlamaktadıral kurulumu, hem frekans ve zaman etki parçacık hareketi analizi ile ilgili bir PZT tutucu ve örnek muhafaza, tuzak yükleme ve veri toplama imalatı. sıvı ortamda bindirme için protokoller de yayınlanmıştır. 15, 16 genel bir deney düzeneği ticari ters optik mikroskop üzerinde geliştirilmiştir. Odaklanmış ışını ile seçilmiş parçacık kaldırma, dinlenme mikro serbest hareketini ölçmek ve tekrar alt-tabaka üzerine yerleştirilmesi: Şekil 1, seçici optik tuzak yükleme aşamaları göstermek için kullanılan düzeneğin şematik bir diyagramını göstermektedir. İlk olarak, çeviri aşamaları (enine ve dikey) bir objektif lens ile odaklanmış bir yakalama lazer (dalga boyu 1064 nm) odak tabaka üzerinde seçilen bir mikropartikul getirmek için kullanılır (yakın-kızılötesi düzeltilmiş uzun çalışma mesafesi amacı: NA 0.4, büyütme 20X, çalışma dsaydam bir zemin ile 20 mm) istance. Sonra, bir piezoelektrik fırlatıcı (mekanik önceden yüklenmiş halka tipi PZT) mikropartiküller ve bir alt tabaka arasındaki yapışmayı kırmak için ultrasonik titreşimler oluşturur. Böylece, herhangi bir serbest parçacık seçilen parçacık odaklanmış tek ışınlı gradyan lazer tuzağı ile kaldırılabilir. Parçacık yakalandığında, elektrostatik uyarma için iki paralel iletken plakalar içeren örnek muhafazanın merkezi çevrilmiştir. Son olarak, bir veri toplama (DAQ) sistemi aynı anda çeyrek hücre fotodetektör (QPD) tarafından yakalanan parçacık hareketi, ve uygulanan elektrik alan kaydeder. ölçüm bittikten sonra, parçacık kontrol edilebilir bir geri bir şekilde daha tuzak böylece alt-tabakanın üzerine yerleştirilir. Bu genel işlem birkaç yakalama döngüsü boyunca ortaya çıkan bu tür iletişim elektrifikasyon gibi değişiklikler ölçmek için parçacık kaybı olmadan yüzlerce kez tekrar edilebilir. Bizim son makale f bakınveya ayrıntılar. 12

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optical trap loading of dielectric microparticles in air

We demonstrate a method to trap a selected dielectric microparticle in air using radiation pressure from a single-beam gradient optical trap. Randomly scattered dielectric microparticles adhered to a glass substrate are momentarily detached using ultrasonic vibrations generated by a piezoelectric transducer (PZT). Then, the optical beam focused on a selected particle lifts it up to the optical trap while the vibrationally excited microparticles fall back to the substrate. A particle may be trapped at the nominal focus of the trapping beam or at a position above the focus (referred to here as the levitation position) where gravity provides the restoring force. After the measurement, the trapped particle can be placed at a desired position on the substrate in a controlled manner. 
In this protocol, an experimental procedure for selective optical trap loading in air is outlined. First, the experimental setup is briefly introduced. Second, the design and fabrication of a PZT holder and a sample enclosure are illustrated in detail. The optical trap loading of a selected microparticle is then demonstrated with step-by-step instructions including sample preparation, launching into the trap, and use of electrostatic force to excite particle motion in the trap and measure charge. Finally, we present recorded particle trajectories of Brownian and ballistic motions of a trapped microparticle in air. These trajectories can be used to measure stiffness or to verify optical alignment through time domain and frequency domain analysis. Selective trap loading enables optical tweezers to track a particle and its changes over repeated trap loadings in a reversible manner, thereby enabling studies of particle-surface interaction.

PZT başlatıcısı CAD yazılım paketi kullanılarak tasarlanmıştır. Şekil 2&#39;de PZT tutucu ve örnek muhafaza materyal ve yöntemler, çeşitli imal edilebilir gösterilen Burada, ön yükleme (a PZT iki plakanın kelepçelenmiştir) için basit bir sandviç yapısı kullanmaktadır. Şekil 2d gösterildiği gibi hızlı bir gösteri için, termoplastik 3D baskı seçin. Yapı parçalarının göre, optik tuzak yükleme Şekil 3</strong...

Watch this Scientific Journal Video about Optical Trap Loading of Dielectric Microparticles In Air at JoVE.com

Optical Trap Loading of Dielectric Microparticles In Air

A protocol for launching and stably trapping selected dielectric microparticles in air is presented.

Havada Dielektrik mikropartiküllerin Optik Tuzak Yükleme

We demonstrate a method to trap a selected dielectric microparticle in air using radiation pressure from a single-beam gradient optical trap. Randomly ...

The goal of this video protocol is to demonstrate how a piezoelectric launcher is constructed and used to overcome particle adhesion and ease particle release from the substrate to achieve micro particle levitation in air. The advantage of launching from a surface is that the particle may be selected based on size, shape, optical properties, or orientation. This last can be useful for trapping asymmetric particles.Repeated trapping and landing of particle can provide a new tool to study questions in surface chemistry, such as charged transfer during the particle's repeat interaction. Returning the particle to the surface also allows subsequent measurements of the same particle by other methods, such as scanning electron microscopy, and also allows repeated cycles of trapping and landing. First, 3D print a rectangular frame in a holder for piezoelectric transducer.Fit the narrow sides of the frame with indium tin oxide coated glass, and the wide sides and top with conventional glass to construct the transparent sample enclosure. Next, pour a small portion of 20 micrometer diameter dielectric micro particles onto a glass slide. Immediately return the container to a desiccator.Using a glass capillary tube, pick up some of the micro particles from the slide. Scatter the particles onto a cover slip by gently tapping the capillary tube. Use a microscope to verify the quantity and distribution of dispersed micro particles on the substrate.Next, begin piezo-launcher assembly by applying insulating film to an aluminum plate. Center a ring type piezoelectric transducer on the plate, ensuring that is separated from the plate by the insulating film. Place the micro particle dispersed cover slip on the transducer, and snap a copper ring into the 3D printed holder.Secure the transducer in place on the plate with the 3D printed holder and two M6 screws. Lightly glue the sample enclosure onto the holder with instant adhesive. Mount the completed launcher assembly on an XYZ translational stage of an inverted optical microscope.Connect the piezoelectric transducer leads to the voltage amplifier, and the amplifier to the function generator, ensuring that all connections are secure and properly grounded. Connect the amplifier monitoring output port to an oscilloscope to monitor the transducer-driving voltage signal. Configure the function generator to send a continuous square wave of zero to one volts to the amplifier.Set the amplifier gain to 200 volts per volt. Set up the microscope to image the micro particles in real time. Then manually scan the modulation frequency of the driving signal from 0 to 150 kilohertz while monitoring the micro particle motion.The piezoelectric assembly is designed to apply mechanical pre-load to the transducer, to amplify the resonance amplitude and reduce failure. Frequencies can help to determine the resonance frequency of transducer by monitoring the particle on the surface. The frequency at which micro particle motion is maximized with no adhered particles is the launcher resonance frequency.Repeat the scan as needed at lower voltages to precisely determine the resonance frequency. Set the wave form to generate a voltage signal at the resonance frequency with a 600 volt amplitude. Configure the function generator for a square wave with 10 to 20 cycles in burst mode.Check that the particles are released after each pulse. If the particles are not released, increase the amplitude or number of cycles. Remove the laser lined filter from the microscope, to locate the focus of the trapping beam on the CCD.Optimize the focus by adjusting the vertical position of the motorized focusing block. Replace the filter, and translate the sample so a selected particle is at the trapping laser focus position. Focus on the particle to image the particle center.Actuate the piezoelectric launcher with several voltage pulses to launch the particle, adjusting the power supply of the electro object modulator as needed. When the particle blurs slightly and begins Brownian motion, trapping has occurred. The focus of trapping beam is critical for successful trap loading.Placing the pin focus few micron below the sample plane helps to increase the trapping efficiency. If the particle only moves slightly and remains in focus on the substrate, increase the trapping power. If the particle flies away to a new location on the surface, decrease the power.Once the particle is successfully loaded, move the objective lens up to translate the levitated particle about one millimeter above the glass cover slip to avoid surface interactions. Then reduce the optical power to move the levitated particle into the more stable nominal trapping position. Move the launcher so the transducer-holder is centered on the optical axis.Move the objective lens to vertically translate the particle higher into the sample enclosure. To begin the measurements, adjust the condenser and focusing lens until the power spectrum density plots of the X and Y channels are well matched. Then connect a high voltage source to the sample enclosure.To measure the trap properties and particle charge, apply an electrostatic field to generate ballistic motion of the particle. Record the step excitation signal in the induced particle trajectory. Average the data for multiple periods as needed to reduce the effects of Brownian motion.After performing the measurement, move the objective lens down to position the particle onto the center of the glass cover slip, to keep it separate from the other particles. The piezoelectric launcher assembly consists of a transparent enclosure to protect the levitated particle from air currents, and a piezoelectric transducer that vibrates the substrate to release the particle. The enclosure bottom is open so that the substrate can be placed directly on the transducer.The micro particles can either be trapped in the levitation position above focus or in the trapping position near focus where optical forces stabilize the particle in all directions. In the levitation position, gravity counteracts the upward radiation pressure so optical forces only stabilize the particle transversely. For small displacements, such as Brownian motion, the optical force can be treated as a linear spring.The resonance frequency can be determined from the power spectral density plot. The trap's stiffness and optical force in the linear regime can then be calculated from the resonance frequency, known mass, and measured displacement. Forces over wider ranges of displacement can be determined from the induced ballistic motion in the applied electric field.Analysis of ballistic displacement by the transient response method gives the resonance frequency, damping, and steady state displacement. Non-linear forces can be determined with the parametric force method. This approach levitating microparticles enables precision measurements using particles selected for size, shape, or material properties, and also allows subsequent measurements on the same particles.Using this method, launching and landing a particle can be repeated over hundred of cycles. This will also allow sensitive studies of particle surface interaction, such as contact electrification with single electron sensitivity.

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