Apoio financeiro parcial para este trabalho foi fornecida pela Fundação Nacional de Ciência dos EUA através do Centro de Pesquisa Cooperativa Indústria / Universidade de Equipamentos &amp; Política localizado na Universidade de Wisconsin-Milwaukee (IIP-0968887) e da Universidade de Marquette (IIP-0.968.844) de água. Agradecemos Glenn M. Walker, Woo-Jin Chang e Shankar Radhakrishnan para discussões úteis.

1. A detecção de partículas térmica (TPD) <ol><li> Prepare o dispositivo de silício micro fabricado com uma película fina membrana de nitreto de silício e sensor de temperatura integrado por micromachining, usando a tecnologia de processamento de semicondutores padrão 2. Lavar o dispositivo fabricado com deionizada (DI) de água. Nota: O processo de fabrico para o detector de partículas térmica dispositivo de microfluidos é explicado na publicação prévia 2. </li><li> Para produzir PDMS (polidimetilsiloxano) substratos com micro-canais, criar um molde SU8 utilizando litografia padrão processa 5. Nota: O tamanho do canal é projetado para a dimensão de cada partícula específico. <ol><li> Adicione PDMS por mistura de uma proporção de 10: 1 da base (30 ml) e agente (3 ml) a cura. Verter o PDMS em que o molde e remover as bolhas por exposição breve a um vácuo (5-10 min). Observação: O nível de vácuo não é um valor crítico para a desgaseificação e que deve continuar até que o gás bubbles são totalmente removido do PDMS mistos. </li><li> Coloque o molde sobre uma placa quente (~ 70 ° C) durante 2 horas para curar o PDMS. Em seguida, retire as PDMS com muito cuidado para não danificar o molde. Observação: O nível de vácuo não é um valor crítico. </li></ol></li><li> Usando um manual punch, perfurar um buraco apertado (1 mm) para o tubo de PTFE em uma extremidade. Utilizar um grande punção (2 mm) na outra extremidade para fazer o PDMS um reservatório. Inserir o micro-canal perfurado na parte superior do dispositivo sob o microscópio e alinhar o RTD no centro do micro-canal (Figura 1A). </li><li> Na interface elétrica, conecte os pinos elétricos nas posições de placa de contato e apertar os parafusos de fixação. Certifique-se os pinos com altura ajustável (Pogo pinos) sentar-se nas almofadas de eletrodo corretas no dispositivo. </li><li> Dilui-se 10 ul das esferas PS concentradas em 100 ul de água desionizada num tubo de 1,5 ml. </li><li> Para garantir o PS grânulos permanecem flutuabilidade neutra, adicionar 2,7 mL de glicerol (1,26g / cm 3) a água desionizada para coincidir com a densidade do fluido para o poliestireno (PS) a densidade do grânulo (1,05 g / cm 3). </li><li> Ligar o tubo de PTFE para o canal em uma extremidade e a outra extremidade a uma seringa de vidro de 1 ml. Encha a seringa de vidro com 0,5 ml de água DI. Nota: ajustada feita selecionando o tamanho soco direito vai evitar vazamentos em tubos. </li><li> Coloque a água Dl preenchido na seringa da bomba de seringa controlada por computador. Empurrar a água (5-20 ul / min) para dentro do canal para preencher todo o canal com o fluido por todo o caminho para o reservatório. </li><li> Carregar 10 ml de solução equilibrada grânulo para o reservatório e introduzir a solução do grânulo para o micro-canal, alterando a direcção do fluxo na bomba de seringa. </li><li> Ligue o RTD por polarização de 1 mA de corrente DC através da controlada computador de origem / metro ao medir a resistência por fonte / metro e classificando os dados medidos (Figura 2). Nota: Durante o experimento, o sensor é tendenciosa; por conseguinte, a temperatura é medida continuamente até ao final da experiência de contagem. O sensor RTD é electricamente polarizado através da aplicação de uma corrente DC na gama de 100 uA a 1 mA para medir continuamente a temperatura até ao fim da experiência de contagem. É crítico para selecionar o nível atual uma vez que existe um trade-off entre o nível de ruído e a amplitude do sinal detectado. A bomba de seringa é utilizada para gerar o fluxo em micro-canal. Seleccionar um caudal apropriado para a realização da experiência TPD é limitada à velocidade da medição. Esta velocidade é uma função da constante de velocidade e o dispositivo eléctrico de medida de tempo térmica. Os resultados da experiência de detecção térmica de partículas são mostrados na Figura 3. </li><li> Utilize o software de processamento de dados desenvolvido (LabVIEW) para converter os dados de resistência medidos a temperatura utilizando a equação de Callendar-Van Dusen 6. </li></ol> 2. térmicaCaracterização de substâncias líquidas Usando um Micro-calorímetro <ol><li> Neste processo, utilizar o dispositivo no chip calorímetro (Figura 4A) 3 para medir a difusividade térmica e calor específico das amostras. Nota: Em cada morrer, há duas câmaras micro-calorímetro (Figura 4B). Cada câmara tem duas entradas e uma saída. E cada uma das câmaras tem um aquecedor e um sensor integrado de IDT. </li><li> Colocar o dispositivo de micro-calorímetro localizado no suporte do dispositivo (Figura 4C). Alinhe o dispositivo para as entradas e saídas de microfluídicos com os acessórios titular. Coloque a camada de selagem de PDMS na parte superior do dispositivo. </li><li> Instale pinos de conexão elétrica no suporte do dispositivo e bloquear os parafusos do suporte. Nota: Certifique-se os Pogo pinos ajustáveis ​​em altura estão alinhados com as almofadas de contato elétrico. </li><li> Instale a camada de interface microfluídico com travas magnéticas para o suporte de dispositivo (Figura 4D). Conecte o PTFE tubos para ambas as entradas e da saída. Conectar uma entrada da bomba de seringa carregadas com amostra e fechar a outra, como a entalpia não é medida, neste caso. </li><li> Utilizar um programa controlado por computador desenvolvido para carregar a amostra para o micro-canais e câmaras. Nota: O programa usará fluxo descontinuada para liberar a pressão excessiva no compartimento suspensos de película fina. <ol><li> Coloque a amostra de 300 ul para a seringa de vidro e coloque-o sobre a bomba de seringa. Use (0,25 mL / min) taxas de fluxo constantes muito lentas para amostras de alta viscosidade (por exemplo, glicerol e líquidos iônicos). Use uma amostra de glicerol para medidas de difusividade térmica e líquidos iônicos para medidas de calor específico. </li></ol></li><li> Medições <ol><li> Medidas de difusividade térmica <ol><li> Ligue a configuração medições, como mostrado na Figura 5A. Carregar a amostra de glicerol para a câmara de micro-calorímetro. Execute o programa de computador controlado modificado para hea<html> t penetração medição do tempo. </li><li> Use a equação penetração de calor calibrado para calcular difusividade térmica a partir do momento penetração de calor medido 7: <img alt="Equação 1" src="/files/ftp_upload/52828/52828eq1.jpg" width="100" /> onde α é difusividade térmica, L é a espessura da câmara, p é o factor de calibração da espessura devido à variação do processo de fabricação, e t 0 é o tempo de penetração de calor. </li></ol></li><li> Medidas de calor específico <ol><li> Utilizar a configuração de medição TWA como mostrado na Figura 5B. Utilizar o mesmo programa de carregamento de amostra e carregar o líquido iónico na câmara. Executar o programa TWA para obter a amplitude das flutuações de temperatura AC (∂ T AC) e utilizar a equação de calor específico para calcular o específico, c p, de calor para cada amostra de líquido iónico 8: &quot;Width =&quot; 117 28eq2.jpg &quot;/&gt; onde C é 0 factor de calibração de potência de entrada, P representa na potência de entrada, ω é a frequência do sinal de actuação, e m é a massa da amostra líquida. </li></ol></li></ol></li></ol> 3. Calorimétrico Detecção Biochemical em dispositivos microfluídicos baseados em papel <ol><li> Use microfabricated película fina (40-50 nm níquel) sensor RTD. Etapas de fabricação para o sensor RTD são explicados em trabalhos anteriores 4. </li><li> Para o canal de fabricação baseado em papel 4, use um plotter faca para cortar o papel canais microfluídicos com um padrão projetado (L-forma). Coloque o papel em cima da esteira de corte, coloque o papel eo tapete de corte para o plotter faca, e usar a receita adequada para cortar os canais microfluídicos de papel 4. </li><li> Por dispositivo e canais de integração, utilizar uma camada adesiva acrílica (5 uM) para integrar o papel sobre o sensor RTD. Use a b limpolade para empurrar o papel para o dispositivo e remover as bolhas de ar (Figura 6A). O filme acrílico é uma camada adesiva para segurar o papel sobre sensor RTD. </li><li> Para a activação da enzima, utilizam tampão acetato de sódio 50 mM para activar a enzima GOD. Adicionar 1 mg de enzima GOD para 1 ml de tampão de acetato de sódio para tornar a solução 1 mg / ml. Ajustar o pH da solução para 5,1. Nota: Ajustar a quantidade de ácido acético em tampão de acetato de sódio para manter o pH da solução 5,1. </li><li> Viés do IDT com 1 mA de corrente DC para ativar o IDT e começar a medir a fonte de resistência / metro continuamente enquanto a resistência se estabelece após o experimento (~ 4 min). Nota: A Figura 6B mostra a configuração de medição para o teste calorimétrico à base de papel. </li><li> Introduzir os 2 ul da solução de GOD preparado para o centro do micro-canal de papel (local imobilização) através de uma pipeta. A temperatura detectada (Figura 7A) deve começar tO diminuir. Nota: O efeito de arrefecimento é devido à temperatura mais elevada a operação de RTD e evaporação da amostra em conjunto. </li><li> Para medir a concentração de glucose, introduzir a solução de controlo de glucose padrão 9 para a entrada do canal e medir a alteração da resistência causada pela reacção. Repita essa experiência com todas as soluções de controle de glicose diferentes (alto, normal e baixas concentrações) e salvar os dados de resistência. </li><li> Utilizando o coeficiente de temperatura de resistência (TCR) por RTD níquel e equação de Callendar-Van Dusen, converter a alteração da resistência à temperatura. Calcula-se a concentração da glicose em cada amostra, considerando a entalpia de reacção da glucose e a enzima GOD (Δ H = -80 kJ / mol) e utilizando a equação de concentração 10: <img alt="Equação 3" src="/files/ftp_upload/52828/52828eq3.jpg" width="83" /> onde n p é detectada uma concentração molar, C <sub&gt; P é a capacidade de calor do sistema e AT é calculada temperatura. </li></ol>

<ol>
	<li>Zhang, H., Chon, C., Pan, X., Li, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Methods+for+counting+particles+in+microfluidic+applications.">Methods for counting particles in microfluidic applications.</a> Microfluid Nanofluid. 7 (6), 739-749 (2009).</li><li>Vutha, A. K., Davaji, B., Lee, C. H., Walker, G. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+microfluidic+device+for+thermal+particle+detection.">A microfluidic device for thermal particle detection.</a> Microfluid Nanofluid. 17 (5), 871-878 (2014).</li><li>Davaji, B., Bak, H. J., Chang, W. J., Lee, C. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Novel+On-chip+Three-dimensional+Micromachined+Calorimeter+with+Fully+Enclosed+and+Suspended+Thin-film+Chamber+for+Thermal+Characterization+of+Liquid+Samples.">A Novel On-chip Three-dimensional Micromachined Calorimeter with Fully Enclosed and Suspended Thin-film Chamber for Thermal Characterization of Liquid Samples.</a> Biomicrofluidics. 8 (3), 034101-034113 (2014).</li><li>Davaji, B., Lee, C. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+paper-based+calorimetric+microfluidics+platform+for+bio-chemical+sensing.">A paper-based calorimetric microfluidics platform for bio-chemical sensing.</a> Biosens. Bioelectron. 59, 120-126 (2014).</li><li>Liu, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Process+research+of+high+aspect+ratio+microstructure+using+SU-8+resist.">Process research of high aspect ratio microstructure using SU-8 resist.</a> Microsystem Technologies. 10, 265-268 (2004).</li><li>Dusen, M. S. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Platinum-resistance+thermometry+at+low+temperatures.">Platinum-resistance thermometry at low temperatures.</a> J. Am. Chem. Soc. 47 (2), 326-332 (1925).</li><li>Arpaci, V. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Conduction Heat Transfer. , (1966).</li><li>Garden, J. L., Chteau, E., Chaussy, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Highly+sensitive+ac+nanocalorimeter+for+microliter-scale+liquids+or+biological+samples.">Highly sensitive ac nanocalorimeter for microliter-scale liquids or biological samples.</a> Appl. Phys. Lett. 84, 3597-3599 (2004).</li><li>Kilo, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evaluation+of+a+New+Blood+Glucose+Monitoring+System+with+Auto-Calibration.">Evaluation of a New Blood Glucose Monitoring System with Auto-Calibration.</a> Diabetes Technol. Ther. 7 (2), 283-294 (2005).</li><li>Scheper, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Thermal Biosensors Bioactivity Bioaffinity (Advances in Biochemical Engineering/Biotechnology). , (1999).</li></ol>

Não há conflitos de interesse declarados.

Different thermal measurement techniques in microfluidic devices and their respective setup procedures are presented in this work. These thermal measurement methods such as thermal conductivity monitoring, thermal penetration time, amplitude of AC thermal fluctuations, and amplitude measurement of the generated heat are used to detect specific substances and investigate different reactions and interactions. 
The thermal time constant plays a key role in the aforementioned thermal measurement t...

Três técnicas de medição térmica de micro-escala diferentes são apresentados neste artigo. As três configurações diferentes de dispositivos microfluidicos são utilizados para a detecção térmica de partículas (TPD), caracterização térmica (condutividade térmica e calor específico), e calorimetria de detecção de reacções químicas e interacções. Detecção de partículas térmica Detecção e contagem de partículas em dispositivos microfluídicos é amplamente utilizado para aplicações ambientais, industriais e biológicos 1. TPD é uma das novas aplicações de medições térmicas em dispositivos microfluídicos 2. Usando a transferência de calor para a detecção e contagem de partículas com base no tamanho de partícula reduz a complexidade, custo e tamanho do sistema. Em outros métodos, óptica complexos ou medições elétricas complexas e software avançado de processamento de sinal são utilizados para a detecção de partículas. Chara térmicacterization de substâncias líquidas Usando Micro-Calorimeter Líquido caracterização térmica da amostra é a segunda aplicação de medição térmica em dispositivos microfluídicos. Executando calorimetria micro-escala vai reduzir o consumo de amostra e aumentar a precisão, oferecendo maior repetibilidade, em comparação com métodos de calorimetria granel convencionais. Os procedimentos de medição de condutividade térmica e calor específico usando o dispositivo micro-calorímetro on-chip são apresentados em outros lugares 3. Os detalhes da técnica o tempo de penetração de calor para a medição da condutividade térmica e a análise de onda térmica (TWA) para medições específicas de calor em dispositivos de microfluidos são descritos na secção de protocolo. Dispositivo micro-Base de Papel Calorimétrico Bio-Chemical Detection em Outra aplicação de medição térmica é a detecção bioquímica em microfluidos baseados em papel. A acção capilar noestrutura porosa de papel transporta o líquido e evita problemas de iniciação bolha em micro-canais. Os mecanismos de detecção mais comuns em dispositivos microfluídicos baseados em papel são técnicas ópticas ou eletroquímicos. Detecção óptica sofre de alta complexidade ea necessidade de software avançado de processamento de imagem para quantificar o sinal detectado. Detecções electroquímica também é limitado dado que eles só podem ser aplicadas a reacções que produzem subprodutos activas. O sensor bioquímica plataforma calorimétrico à base de papel recentemente introduzida 4 leva vantagem de o sistema de microfluidos à base de papel e o mecanismo de detecção térmica livre de marcador. Os procedimentos de detecção de glucose através de calorimetria de enzima glucose oxidase (GOD) em uma plataforma de microfluidos à base de papel são apresentados na secção de protocolo. O objetivo deste artigo é demonstrar as capacidades de técnicas termais de medição em dispositivos microfluídicos. O dispositivo preparation, amostra de líquido detector manuseio e resistência à temperatura (RTD) de excitação do sensor e medição são apresentados nas próximas seções.

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>Polydimethylsiloxane (PDMS)&#160;</td>
			<td>Dow Corning</td>
			<td>Sylgard 184</td>
			<td></td>
		</tr>
		<tr>
			<td>PS beads - 90 um&#160;</td>
			<td>Corpuscular</td>
			<td>100265</td>
			<td></td>
		</tr>
		<tr>
			<td>PS beads - 200 um&#160;</td>
			<td>Corpuscular</td>
			<td>100271</td>
			<td></td>
		</tr>
		<tr>
			<td>Glycerol</td>
			<td>SigmaAldrich</td>
			<td>G5516</td>
			<td></td>
		</tr>
		<tr>
			<td>GOD enzyme</td>
			<td>SigmaAldrich</td>
			<td>G7141</td>
			<td></td>
		</tr>
		<tr>
			<td>Glucose Control Solution-Low</td>
			<td>Bayer contour</td>
			<td>Low Control</td>
			<td></td>
		</tr>
		<tr>
			<td>Glucose Control Solution-Normal</td>
			<td>Bayer contour</td>
			<td>Normal Control</td>
			<td></td>
		</tr>
		<tr>
			<td>Glucose Control Solution-High</td>
			<td>Bayer contour</td>
			<td>High Control</td>
			<td></td>
		</tr>
		<tr>
			<td>Chromatography filter paper</td>
			<td>Whatman</td>
			<td>3001-845</td>
			<td></td>
		</tr>
		<tr>
			<td>Glass</td>
			<td>VWR&#160;</td>
			<td>48393-106</td>
			<td></td>
		</tr>
		<tr>
			<td>Acrylic Film</td>
			<td>Nitto Denko</td>
			<td>5600</td>
			<td></td>
		</tr>
		<tr>
			<td>Glass syringe (1 mL)</td>
			<td>Hamilton</td>
			<td>1001</td>
			<td></td>
		</tr>
		<tr>
			<td>Syringe pump</td>
			<td>New Era</td>
			<td>NE-500</td>
			<td></td>
		</tr>
		<tr>
			<td>knife plotter</td>
			<td>Silhouette</td>
			<td>portrait</td>
			<td></td>
		</tr>
		<tr>
			<td>Current Preamplifier</td>
			<td>Stanford Research</td>
			<td>SR-570</td>
			<td></td>
		</tr>
		<tr>
			<td>Ocilloscope</td>
			<td>Agilent</td>
			<td>DSO 2420A</td>
			<td></td>
		</tr>
		<tr>
			<td>Signal Generator</td>
			<td>HP</td>
			<td>HP3324A</td>
			<td></td>
		</tr>
		<tr>
			<td>Lock-in Amplifire</td>
			<td>Stanford Research</td>
			<td>SRS-830</td>
			<td></td>
		</tr>
		<tr>
			<td>Source/meter 2400</td>
			<td>Keithley</td>
			<td>2400</td>
			<td></td>
		</tr>
		<tr>
			<td>Source/meter 2600</td>
			<td>Keithley</td>
			<td>2436A</td>
			<td></td>
		</tr>
	</tbody>
</table>

thermal measurement techniques in analytical microfluidic devices

Thermal measurement techniques have been used for many applications such as thermal characterization of materials and chemical reaction detection. Micromachining techniques allow reduction of the thermal mass of fabricated structures and introduce the possibility to perform high sensitivity thermal measurements in the micro-scale and nano-scale devices. Combining thermal measurement techniques with microfluidic devices allows performing different analytical measurements with low sample consumption and reduced measurement time by integrating the miniaturized system on a single chip. The procedures of thermal measurement techniques for particle detection, material characterization, and chemical detection are introduced in this paper.

A Figura 3 mostra o gráfico do sinal térmico medido. Os sinais gerados na presença dos grânulos com imagens ópticas correspondentes mostram a detecção com sucesso das microesferas PS no micro-canal. A condutividade térmica do líquido que passa através do microcanal está a mudar devido à presença de grânulos de PS. Esta alteração na condutividade térmica do canal está a afectar a transferência de calor no micro-canal. A alteração na transferência de calor no micro-canal é detectado...

Watch this Scientific Journal Video about Thermal Measurement Techniques in Analytical Microfluidic Devices at JoVE.com

Thermal Measurement Techniques in Analytical Microfluidic Devices

Here, we present three protocols for thermal measurements in microfluidic devices.

Técnicas de Medição térmicos em analíticos microfluídicos

Thermal measurement techniques have been used for many applications such as thermal characterization of materials and chemical reaction detection. ...

thermal-measurement-techniques-in-analytical-microfluidic-devices

Research

JoVE Journal

Engineering

9.5K visualizações.  Marquette University. Here, we present three protocols for thermal measurements in microfluidic devices. 

Vídeo: Thermal Measurement Techniques in Analytical Microfluidic Devices

Characterization of Thermal Transport in One-dimensional Solid Materials

The TET (transient electro-thermal) technique is an effective approach developed to measure the thermal diffusivity of solid materials, including conductive, semi-conductive or nonconductive one-dimensional structures. This technique broadens the measurement scope of materials (conductive and nonconductive) and improves the accuracy and stability. If the sample (especially biomaterials, such as human head hair, spider silk, and silkworm silk) is not conductive, it will be coated with a gold layer to make it electronically conductive. The effect of parasitic conduction and radiative losses on the thermal diffusivity can be subtracted during data processing. Then the real thermal conductivity can be calculated with the given value of volume-based specific heat (&#961;cp), which can be obtained from calibration, noncontact photo-thermal technique or measuring the density and specific heat separately. In this work, human head hair samples are used to show how to set up the experiment, process the experimental data, and subtract the effect of parasitic conduction and radiative losses.

The TET (transient electro-thermal) technique is an effective approach developed to measure the thermal diffusivity of solid materials.

Caracterização dos Transportes térmica em materiais sólidos unidimensionais

The TET (transient electro-thermal) technique is an effective approach developed to measure the thermal diffusivity of solid materials, including ...

Engenharia

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.

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

Armadilha óptica carregamento de dielétrico micropartículas no ar

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

Solvent Bonding for Fabrication of PMMA and COP Microfluidic Devices

Thermoplastic microfluidic devices offer many advantages over those made from silicone elastomers, but bonding procedures must be developed for each thermoplastic of interest. Solvent bonding is a simple and versatile method that can be used to fabricate devices from a variety of plastics. An appropriate solvent is added between two device layers to be bonded, and heat and pressure are applied to the device to facilitate the bonding. By using an appropriate combination of solvent, plastic, heat, and pressure, the device can be sealed with a high quality bond, characterized as having high bond coverage, bond strength, optical clarity, durability over time, and low deformation or damage to microfeature geometry. We describe the procedure for bonding devices made from two popular thermoplastics, poly(methyl-methacrylate) (PMMA), and cyclo-olefin polymer (COP), as well as a variety of methods to characterize the quality of the resulting bonds, and strategies to troubleshoot low quality bonds. These methods can be used to develop new solvent bonding protocols for other plastic-solvent systems.

Solvent bonding is a simple and versatile method for fabricating thermoplastic microfluidic devices with high quality bonds. We describe a protocol to achieve strong, optically clear bonds in PMMA and COP microfluidic devices that preserve microfeature details, by a judicious combination of pressure, temperature, an appropriate solvent, and device geometry.

Bonding solvente para Fabricação de PMMA e COP microfluídicos

Thermoplastic microfluidic devices offer many advantages over those made from silicone elastomers, but bonding procedures must be developed for each ...

Micro/Nano-scale Strain Distribution Measurement from Sampling Moir&#233; Fringes

This work describes the measurement procedure and principles of a sampling moir&#233; technique for full-field micro/nano-scale deformation measurements. The developed technique can be performed in two ways: using the reconstructed multiplication moir&#233; method or the spatial phase-shifting sampling moir&#233; method. When the specimen grid pitch is around 2 pixels, 2-pixel sampling moir&#233; fringes are generated to reconstruct a multiplication moir&#233; pattern for a deformation measurement. Both the displacement and strain sensitivities are twice as high as in the traditional scanning moir&#233; method in the same wide field of view. When the specimen grid pitch is around or greater than 3 pixels, multi-pixel sampling moir&#233; fringes are generated, and a spatial phase-shifting technique is combined for a full-field deformation measurement. The strain measurement accuracy is significantly improved, and automatic batch measurement is easily achievable. Both methods can measure the two-dimensional (2D) strain distributions from a single-shot grid image without rotating the specimen or scanning lines, as in traditional moir&#233; techniques. As examples, the 2D displacement and strain distributions, including the shear strains of two carbon fiber-reinforced plastic specimens, were measured in three-point bending tests. The proposed technique is expected to play an important role in the non-destructive quantitative evaluations of mechanical properties, crack occurrences, and residual stresses of a variety of materials.

Micro/Nano-scale Strain Distribution Measurement from Sampling Moir&amp;#233; Fringes

A sampling moir&#233; technique featuring 2-pixel and multi-pixel sampling methods for high-accuracy strain distribution measurements at the micro/nano-scale is presented here.

Medição de Distribuição de Estirpes Micro / Nano-escala a partir da Amostragem Frisos Moiré

This work describes the measurement procedure and principles of a sampling moir&#233; technique for full-field micro/nano-scale deformation measurements. ...

Generation of Size-controlled Poly (ethylene Glycol) Diacrylate Droplets via Semi-3-Dimensional Flow Focusing Microfluidic Devices

Uniform and size-controllable poly (ethylene glycol) diacrylate (PEGDA) droplets could be produced via the flow focusing process in a microfluidic device. This paper proposes a semi-three-dimensional (semi-3D) flow-focusing microfluidic chip for droplet formation. The polydimethylsiloxane (PDMS) chip was fabricated using the multi-layer soft lithography method. Hexadecane containing surfactant was used as the continuous phase, and PEGDA with the ultraviolet (UV) photo-initiator was the dispersed phase. Surfactants allowed the local surface tension to drop and formed a more cusped tip which promoted breaking into tiny micro-droplets. As the pressure of dispersed phase was constant, the size of droplets became smaller with increasing continuous phase pressure before dispersed phase flow was broken off. As a result, droplets with size variation from 1 &#181;m to 80 &#181;m in diameter could be selectively achieved by changing the pressure ratio in two inlet channels, and the average coefficient of variation was estimated to be below 7%. Furthermore, droplets could turn into micro-beads by UV exposure for photo-polymerization. Conjugating biomolecules on such micro-beads surface have many potential applications in the fields of biology and chemistry.

Generation of Size-controlled Poly ethylene Glycol Diacrylate Droplets via Semi-3-Dimensional Flow Focusing Microfluidic Devices

Here, we present a protocol to illustrate the fabrication processes and verifying experiments of a semi-three-dimensional (semi-3D) flow-focusing microfluidic chip for droplet formation.

Geração de tamanho controlado poli (etileno glicol) Diacrylate gotículas através de Semi-3-Dimensional Flow focando Microfluidic dispositivos

Uniform and size-controllable poly (ethylene glycol) diacrylate (PEGDA) droplets could be produced via the flow focusing process in a microfluidic device. ...

Simultaneous Measurement of Turbulence and Particle Kinematics Using Flow Imaging Techniques

Numerous problems in scientific and engineering fields involve understanding the kinematics of particles in turbulent flows, such as contaminants, marine micro-organisms, and/or sediments in the ocean, or fluidized bed reactors and combustion processes in engineered systems. In order to study the effect of turbulence on the kinematics of particles in such flows, simultaneous measurements of both the flow and particle kinematics are required. Non-intrusive, optical flow measurement techniques for measuring turbulence, or for tracking particles, exist but measuring both simultaneously can be challenging due to interference between the techniques. The method presented herein provides a low cost and relatively simple method to make simultaneous measurements of the flow and particle kinematics. A cross section of the flow is measured using a particle image velocimetry (PIV) technique, which provides two components of velocity in the measurement plane. This technique utilizes a pulsed-laser for illumination of the seeded flow field that is imaged by a digital camera. The particle kinematics are simultaneously imaged using a light emitting diode (LED) line light that illuminates a planar cross section of the flow that overlaps with the PIV field-of-view (FOV). The line light is of low enough power that it does not affect the PIV measurements, but powerful enough to illuminate the larger particles of interest imaged using the high-speed camera. High-speed images that contain the laser pulses from the PIV technique are easily filtered by examining the summed intensity level of each high-speed image. By making the frame rate of the high-speed camera incommensurate with that of the PIV camera frame rate, the number of contaminated frames in the high-speed time series can be minimized. The technique is suitable for mean flows that are predominantly two-dimensional, contain particles that are at least 5 times the mean diameter of the PIV seeding tracers, and are low in concentration.

The technique described herein offers a low cost and relatively simple method to simultaneously measure particle kinematics and turbulence in flows with low particle concentrations. The turbulence is measured using particle image velocimetry (PIV), and particle kinematics are calculated from images obtained with a high-speed camera in an overlapping field-of-view.

Medição simultânea de turbulência e cinemática das partículas usando o fluxo de imagens técnicas

Numerous problems in scientific and engineering fields involve understanding the kinematics of particles in turbulent flows, such as contaminants, marine ...

Method Development for Contactless Resonant Cavity Dielectric Spectroscopic Studies of Cellulosic Paper

The current analytical techniques for characterizing printing and graphic arts substrates are largely ex situ and destructive. This limits the amount of data that can be obtained from an individual sample and renders it difficult to produce statistically relevant data for unique and rare materials. Resonant cavity dielectric spectroscopy is a non-destructive, contactless technique which can simultaneously interrogate both sides of a sheeted material and provide measurements which are suitable for statistical interpretations. This offers analysts the ability to quickly discriminate between sheeted materials based on composition and storage history. In this methodology article, we demonstrate how contactless resonant cavity dielectric spectroscopy may be used to differentiate between paper analytes of varying fiber species compositions, to determine the relative age of the paper, and to detect and quantify the amount of post-consumer waste (PCW) recycled fiber content in manufactured office paper.

A protocol for the non-destructive analysis of the fiber content and relative age of paper.

Desenvolvimento de método para estudos espectroscópicos dielétricos de cavidade ressonante sem contato de papel Celulóico

The current analytical techniques for characterizing printing and graphic arts substrates are largely ex situ and destructive. This limits the amount of ...

Fabrication of Nanoheight Channels Incorporating Surface Acoustic Wave Actuation via Lithium Niobate for Acoustic Nanofluidics

Controlled nanoscale manipulation of fluids is known to be exceptionally difficult due to the dominance of surface and viscous forces. Megahertz-order surface acoustic wave (SAW) devices generate tremendous acceleration on their surface, up to 108 m/s2, in turn responsible for many of the observed effects that have come to define acoustofluidics: acoustic streaming and acoustic radiation forces. These effects have been used for particle, cell, and fluid manipulation at the microscale, although more recently SAW has been used to produce similar phenomena at the nanoscale through an entirely different set of mechanisms. Controllable nanoscale fluid manipulation offers a broad range of opportunities in ultrafast fluid pumping and biomacromolecule dynamics useful for physical and biological applications. Here, we demonstrate nanoscale-height channel fabrication via room-temperature lithium niobate (LN) bonding integrated with a SAW device. We describe the entire experimental process including nano-height channel fabrication via dry etching, plasma-activated bonding on lithium niobate, the appropriate optical setup for subsequent imaging, and SAW actuation. We show representative results for fluid capillary filling and fluid draining in a nanoscale channel induced by SAW. This procedure offers a practical protocol for nanoscale channel fabrication and integration with SAW devices useful to build upon for future nanofluidics applications.

We demonstrate fabrication of nanoheight channels with the integration of surface acoustic wave actuation devices upon lithium niobate for acoustic nanofluidics via liftoff photolithography, nano-depth reactive ion etching, and room-temperature plasma surface-activated multilayer bonding of single-crystal lithium niobate, a process similarly useful for bonding lithium niobate to oxides.

Fabricação de canais de nanoaltura incorporando atuação de onda acústica superficial via Niobate de lítio para nanofluidos acústicos

Controlled nanoscale manipulation of fluids is known to be exceptionally difficult due to the dominance of surface and viscous forces. Megahertz-order ...

In Situ Surface Temperature Measurement in a Conveyor Belt Furnace via Inline Infrared Thermography

Measuring the surface temperature of objects that are processed in conveyor belt furnaces is an important tool in process control and quality assurance. Currently, the surface temperature of objects processed in conveyor belt furnaces is typically measured via thermocouples. However, infrared (IR) thermography presents multiple advantages compared to thermocouple measurements, as it is a contactless, real-time, and spatially resolved method. Here, as a representative proof-of-concept example, an inline thermography system is successfully installed into an IR lamp powered solar firing furnace, which is used for the contact firing process of industrial Si solar cells. This protocol describes how to install an IR camera into a conveyor belt furnace, conduct a customer correction of a factory calibrated IR camera, and perform the evaluation of spatial surface temperature distribution on a target object.

This protocol describes how to install an infrared camera into a conveyor belt furnace, conduct a customer correction of a factory calibrated IR camera, and evaluate the spatial surface temperature distribution of an object of interest. The example objects are industrial silicon solar cells.

Em Situ Surface Temperature Measurement em um forno de correia transportadora através de Termografia Infravermelha Inline

Measuring the surface temperature of objects that are processed in conveyor belt furnaces is an important tool in process control and quality assurance. ...

Microfluidic Fabrication Techniques for High-Pressure Testing of Microscale Supercritical CO2 Foam Transport in Fractured Unconventional Reservoirs

Pressure limitations of many microfluidic platforms have been a significant challenge in microfluidic experimental studies of fractured media. As a result, these platforms have not been fully exploited for direct observation of high-pressure transport in fractures. This work introduces microfluidic platforms that enable direct observation of multiphase flow in devices featuring surrogate permeable media and fractured systems. Such platforms provide a pathway to address important and timely questions such as those related to CO2 capture, utilization and storage. This work provides a detailed description of the fabrication techniques and an experimental setup that may serve to analyze the behavior of supercritical CO2 (scCO2) foam, its structure and stability. Such studies provide important insights regarding enhanced oil recovery processes and the role of hydraulic fractures in resource recovery from unconventional reservoirs. This work presents a comparative study of microfluidic devices developed using two different techniques: photolithography/wet-etching/thermal-bonding versus Selective Laser-induced Etching. Both techniques result in devices that are chemically and physically resistant and tolerant of high pressure and temperature conditions that correspond to subsurface systems of interest. Both techniques provide pathways to high-precision etched microchannels and capable lab-on-chip devices. Photolithography/wet-etching, however, enables fabrication of complex channel networks with complex geometries, which would be a challenging task for laser etching techniques. This work summarizes a step-by-step photolithography, wet-etching and glass thermal-bonding protocol and, presents representative observations of foam transport with relevance to oil recovery from unconventional tight and shale formations. Finally, this work describes the use of a high-resolution monochromatic sensor to observe scCO2 foam behavior where the entirety of the permeable medium is observed simultaneously while preserving the resolution needed to resolve features as small as 10 &#181;m.

Microfluidic Fabrication Techniques for High-Pressure Testing of Microscale Supercritical CO2 Foam Transport in Fractured Unconventional Reservoirs

This paper describes a protocol along with a comparative study of two microfluidic fabrication techniques, namely photolithography/wet-etching/thermal-bonding and Selective Laser-induced Etching (SLE), that are suitable for high-pressure conditions. These techniques constitute enabling platforms for direct observation of fluid flow in surrogate permeable media and fractured systems under reservoir conditions.

Técnicas de fabricação microfluidica para testes de alta pressão do transporte de espuma de CO2 supercrítica de microescala em reservatórios não convencionais fraturados

Pressure limitations of many microfluidic platforms have been a significant challenge in microfluidic experimental studies of fractured media. As a ...