Name: laser-induced forward transfer for flip-chip packaging of single dies
Uploaded: 2015-03-20T14:00:00.000+00:00
Duration: 8 min 21 s
Description: Watch this Scientific Journal Video about Laser-induced Forward Transfer for Flip-chip Packaging of Single Dies at JoVE.com

This work was carried out in the framework of the project &#8220;MIRAGE,&#8221; funded by the European Commission within the FP7 program.

1. LIFT-assistita flip-chip Bonding NOTA: Ci sono tre fasi coinvolte nella realizzazione assemblee flip-chip di LIFT-assistita, vale a dire-micro-urto dei substrati con la tecnica LIFT, allegando i chip optoelettronici ai substrati urtato con termo-compressione flip-chip di metodo di collegamento, e infine incapsulamento delle assemblee incollati. Ognuna di queste fasi è discusso nelle seguenti sezioni: <ol><li> Micro-urto con LIFT: <ol><li> Per la preparazione del donatore, depositare un film sottile di materiale donatore su un substrato portante laser-trasparente. Per questo esperimento, evaporare a 200 nm film spesso di metallo indio sopra vetro substrato di supporto con dimensioni: spessore del diametro x 0,05 centimetri 2 pollici. NOTA: metodo di preparazione del donatore dipende dalla fase del materiale donatore, ad esempio, utilizzare evaporazione e sputtering per materiali donatori fase solida e spin-coating e medico-palettatura per donatore fase liquidas. </li><li> Per la preparazione del ricevitore, utilizzare substrati di vetro con dimensioni di 5 x 5 x 0,07 centimetri 3 come ricevitori. Motivo questi substrati con le pastiglie di contatto metallici per l&#39;incollaggio il chip OE e fan-out di sondaggio strutture usando fotolitografia. Per questo esperimento, spessi rilievi obbligazionari Ni-Au pattern 4 micron e fan-out sondare piste su substrati di vetro del ricevitore. </li><li> Quindi, posizionare il donatore in contatto con il ricevitore e montare il gruppo donatore-ricevente su una fase di traduzione XY controllata dal computer. NOTA: A seconda della fase del materiale donatore (per esempio, solidi (indio) o liquido (inchiostro / incollare)) e il suo spessore, il donatore e substrati ricevitore sono posti a una separazione ottimale che può essere facilmente controllato (per esempio, mediante utilizzando distanziatori metallici). </li><li> Mettere a fuoco il fascio laser incidente all&#39;interfaccia carrier-donatore impiegando un obiettivo da 160 mm di lunghezza focale e la scansione del fascio (20 micron dimensione dello spot) in tutto il substrat donatoree per il trasferimento dei donatori micro-urti sul ricevitore obbligazionari-pad. Utilizzare una sorgente laser al picosecondo di 355 nm di lunghezza d&#39;onda e 12 durata dell&#39;impulso psec a LIFT urti indio sul ricevitore obbligazioni pad alla fluenza di 270 mJ / cm 2. NOTA: Le proprietà laser come l&#39;energia, no. di impulsi, l&#39;altezza della lente dell&#39;obiettivo, coordinate della posizione esatta sul substrato ricevente per la stampa donatori micro-urti e il pattern desiderato da trasferire sono accuratamente controllata da un programma per computer. Parametri sperimentali chiave (ad esempio, il trasferimento di fluenza) devono essere ottimizzati in caso di utilizzo di un&#39;altra sorgente laser. </li><li> Per urti spessi spostare il donatore a un luogo fresco e ripetere passo 1.1.4 più volte. Ad esempio, ripetere il punto 1.1.4 a sei volte per ottenere una pila di 6 dossi indio stampate su uno sopra l&#39;altro per questo esperimento. La finale sollevò dossi hanno un&#39;altezza media di circa 1,5 micron e un diametro di 20 micron (Figura 2). NOTA: Per questi speriments il profilo della superficie e lo spessore degli urti sono stati misurati utilizzando un profilometro ottico. E &#39;stato verificato che le asperità avevano una morfologia convesso / cupola con uno spessore medio di 1,5 micron, una media di oltre il diametro urto (come indicato giallo in figura 3). La ragione di questo è attribuita al fatto che il donatore fuso nella zona laser irradiato e il pellet trasferito poi ri-solidificato raggiungimento superficie del ricevitore (Indium ha un basso punto di fusione). Il vantaggio di questo è che risulta in buona adesione della urto stampata alle piazzole di contatto VCSEL. </li></ol></li><li> Chip al supporto adesivo termo-compressione (Figure 4-6): <ol><li> Utilizzare una semiautomatica flip-chip di bonder per incollare i chip optoelettronici ai substrati urtato. </li><li> Caricare il ricevitore urtato e il chip da incollare sui rispettivi piatti vuoto del bonder. Posizionare il chip in posizione capovolta, cioè, con la sua area attiva facmento. </li><li> Utilizzare un utensile prelevatore adatto e allinearlo al centro del chip. Utilizzare un utensile a forma di ago, come mostrato in Figura 5. Successivamente, scegliere il chip utilizzando questo strumento di accompagnamento. </li><li> Allineare i chip di obbligazioni pad con le pastiglie di contatto corrispondenti sul substrato ricevitore utilizzando un sistema di telecamere di allineamento. </li><li> Una volta allineato posto il chip sul substrato. </li><li> Applicare calore (~ 200 ° C) e pressione (12,5 gf / urto) simultaneamente per realizzare chip substrato interconnessioni elettriche e meccaniche. </li></ol></li><li> Incapsulamento delle assemblee incollati (Figure 4-6): <ol><li> Erogare un adesivo otticamente trasparente attorno ai bordi del complesso legato utilizzando un ago della siringa. L&#39;incapsulamento aumenta l&#39;affidabilità meccanica degli assemblaggi incollati. Utilizzare un singolo componente UV adesivo curabile come NOA 86 per incapsulare i chip legati. </li><li> Curare l&#39;adesivo con una lampada UV per ~ 30 sec. </li></ol></li></ol> 2. Caratterizzazione dei Bonded verticale-cavità superficie di uscita laser (VCSEL) NOTA: Dopo la fabbricazione il prossimo passo è quello di valutare la performance elettro-ottico delle assemblee incollati. Il light-corrente-tensione (LIV) curve dei dispositivi sono registrati post-bonding utilizzando una stazione di sonda. Le seguenti operazioni sono coinvolti per la sperimentazione: <ol><li> Posizionare il flip-chip legato dispositivo su un palco trasparente su misura. Lo stadio ha un foro nel centro per un facile accesso alla luce emessa dai VCSEL. </li><li> Inserire un fotorivelatore (PD) sotto la fase trasparente e allineare la sua area attiva con il chip incollato utilizzando un microscopio. </li><li> Proprio posizionare gli aghi di sondaggio sul Ni-Au sonda pad utilizzando un microscopio. </li><li> Iniettare fino a 10 mA di corrente e misurare la caduta di tensione attraverso il VCSEL e la luce emessa da utilizzando una corrente / tensione unità sorgente metri e un misuratore di potenza resture rispettivamente. </li></ol>

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The authors have nothing to disclose.

In questo lavoro, abbiamo dimostrato termocompressione Flip-chip bonding di chip VCSEL singoli utilizzando una tecnica di scrittura diretta basata sul laser chiamato LIFT. Le fasi di fabbricazione assemblaggio coinvolte stampa dei micro-urti di indio sulle piazzole di contatto del substrato con la tecnica ascensore. Questo è stato seguito da termocompressione Flip-chip bonding di chip VCSEL ai substrati urtato e infine la loro incapsulamento. Elettrica, ottica e meccanica affidabilità dei ...

Laser-indotta Transfer Forward (LIFT) è un metodo di produzione versatile-scrittura diretta additivo per la definizione del modello single-step e il trasferimento di materiale con micron e sub-micron-risoluzione. In questo lavoro, si segnala l&#39;uso di LIFT come tecnica sbattere per il confezionamento flip-chip verticale-cavità superficie di uscita laser (VCSEL) su un chip-scala. Flip-chip è una tecnologia chiave nella confezione sistema ed integrazione di (OE) componenti elettronici ed optoelettronici. Per raggiungere densa integrazione di componenti fini incollaggio pitch è essenziale. Anche se passo fine legame è stato dimostrato da alcune delle tecniche standard, ma c&#39;è un vuoto in termini di combinare insieme le altre caratteristiche importanti come la flessibilità, economicità, velocità, precisione e bassa temperatura di lavorazione. Per soddisfare queste esigenze abbiamo dimostrato il metodo di incollaggio LIFT-assistita termo-compressione per passo fine incollaggio di componenti OE. In LIFT, una sottile pellicola di materiale da stampare (denominato donatore) viene depositata su una faccia di un substrato di supporto laser trasparente (denominato carrier). La Figura 1 illustra il principio di base di questa tecnica. Un impulso laser incidente di intensità sufficiente viene poi concentrata all&#39;interfaccia carrier-donatore che fornisce la forza propulsiva necessaria per trasmettere trasferire il pixel donatore dalla zona irradiata su un altro substrato (denominato ricevitore) posto in prossimità. LIFT è stata segnalata per la prima nel 1986 da Bohandy come tecnica per stampare linee in rame micron di dimensioni per la riparazione di danni foto-maschera 3. Dalla sua prima dimostrazione questa tecnica ha raggiunto livelli significativi come tecnologia di fabbricazione di micro-nano per patterning controllata e la stampa di una vasta gamma di materiali come la ceramica 4, 5, CNT QD 6, 7 cellule viventi, il graficoene 8, per le diverse applicazioni, quali biosensori 9, OLED 10, componenti optoelettronici 11, sensori plasmoniche 12, organico-elettronica 13 e legame 14,15 flip-chip. LIFT offre diversi vantaggi rispetto le flip-chip di urti e incollaggio tecniche esistenti, quali la semplicità, velocità, flessibilità, economicità, ad alta risoluzione e precisione per il confezionamento flip-chip componenti OE.

<table><tbody><tr><td>Laser source</td><td>3D MicroMac (3DMM)</td><td>2912-295</td><td></td></tr><tr><td>Photodetector</td><td>Newport&amp;nbsp;</td><td>818 series</td><td></td></tr><tr><td>Source measurement unit</td><td>Keithley&amp;nbsp;</td><td>2401</td><td></td></tr><tr><td>Power meter</td><td>Newport&amp;nbsp;</td><td>1930</td><td></td></tr><tr><td>Underfill</td><td>Norlands</td><td>NOA 86</td><td></td></tr><tr><td>UV lamp</td><td>Omnicure</td><td>Series 1000 UV</td><td></td></tr><tr><td>Probe station</td><td>Cascade Microtech</td><td>model 42</td><td></td></tr><tr><td>Flip-chip bonder</td><td>Dr. Tresky</td><td>T-320 X</td><td></td></tr></tbody></table>

laser-induced forward transfer for flip-chip packaging of single dies

Flip-chip (FC) imballaggio è una tecnologia chiave per realizzare elevate prestazioni, circuiti ultra-miniaturizzato e alta densità nell&#39;industria microelettronica. In questa tecnica il chip e / o il substrato è urtato ei due sono legati tramite questi urti conduttivi. Molte tecniche bumping sono state sviluppate e intensamente indagato dopo l&#39;introduzione della tecnologia FC nel 1960 1 come la stampa stencil, stallone urto, l&#39;evaporazione e electroless / galvanica 2. Nonostante i progressi che questi metodi hanno tutti soffrono di uno o più di inconvenienti che devono essere affrontati come costo, fasi di elaborazione complesse, alte temperature di lavorazione, il tempo di fabbricazione e soprattutto la mancanza di flessibilità. In questo lavoro, dimostriamo un laser-based urto tecnica di formatura semplice e conveniente nota come Laser indotta Transfer Forward (LIFT) 3. Utilizzando la tecnica LIFT una vasta gamma di materiali urto può be stampato in un unico passaggio, con grande flessibilità, ad alta velocità e la precisione a RT. Inoltre, LIFT permette di urtare e legame verso il basso per chip-scale, che è fondamentale per la realizzazione di un circuito ultra-miniatura.

La figura 7 mostra una curva tipica LIV che è stato registrato da uno dei tanti flip-chip di circuiti integrati VCSEL incollati. Una buona corrispondenza tra la potenza ottica misurata al fornitore citato valori indicati buon funzionamento del periferiche associate post-bonding. Le curve sono state registrate anche prior- e post-incapsulamento e sul confronto è stato verificato che l&#39;incapsulante non ha avuto effetto sulla funzionalità del circuito integrato (come mostrato nella Figura 7)...

Watch this Scientific Journal Video about Laser-induced Forward Transfer for Flip-chip Packaging of Single Dies at JoVE.com

Laser-induced Forward Transfer for Flip-chip Packaging of Single Dies

Dimostriamo l&#39;uso della Forward Transfer (LIFT) tecnica laser-indotta per l&#39;assemblaggio flip-chip componenti optoelettronici. Questo approccio fornisce un conveniente, a bassa temperatura semplice, soluzione veloce e flessibile per la messa a passo urti e incollaggio sul chip-scala per raggiungere i circuiti ad alta densità per applicazioni optoelettroniche.

Laser-indotta Transfer Forward per Flip-chip Packaging di Dies Singolo

Flip-chip (FC) packaging is a key technology for realizing high performance, ultra-miniaturized and high-density circuits in the micro-electronics ...

laser-induced-forward-transfer-for-flip-chip-packaging-of-single-dies

Research

JoVE Journal

Engineering

12.3K Views.  Ghent University-imec.  Dimostriamo l'uso della Forward Transfer (LIFT) tecnica laser-indotta per l'assemblaggio flip-chip componenti optoelettronici. Questo approccio fornisce un conveniente, a bassa temperatura semplice, soluzione veloce e flessibile per la messa a passo urti e incollaggio sul chip-scala per raggiungere i circuiti ad alta densità per applicazioni optoelettroniche. 

Video: Laser-induced Forward Transfer for Flip-chip Packaging of Single Dies

Lensless Fluorescent Microscopy on a Chip

On-chip lensless imaging in general aims to replace bulky lens-based optical microscopes with simpler and more compact designs, especially for high-throughput screening applications. This emerging technology platform has the potential to eliminate the need for bulky and/or costly optical components through the help of novel theories and digital reconstruction algorithms. Along the same lines, here we demonstrate an on-chip fluorescent microscopy modality that can achieve e.g., &lt;4&mu;m spatial resolution over an ultra-wide field-of-view (FOV) of &gt;0.6-8 cm2 without the use of any lenses, mechanical-scanning or thin-film based interference filters. In this technique, fluorescent excitation is achieved through a prism or hemispherical-glass interface illuminated by an incoherent source. After interacting with the entire object volume, this excitation light is rejected by total-internal-reflection (TIR) process that is occurring at the bottom of the sample micro-fluidic chip. The fluorescent emission from the excited objects is then collected by a fiber-optic faceplate or a taper and is delivered to an optoelectronic sensor array such as a charge-coupled-device (CCD). By using a compressive-sampling based decoding algorithm, the acquired lensfree raw fluorescent images of the sample can be rapidly processed to yield e.g., &lt;4&mu;m resolution over an FOV of &gt;0.6-8 cm2. Moreover, vertically stacked micro-channels that are separated by e.g., 50-100 &mu;m can also be successfully imaged using the same lensfree on-chip microscopy platform, which further increases the overall throughput of this modality. This compact on-chip fluorescent imaging platform, with a rapid compressive decoder behind it, could be rather valuable for high-throughput cytometry, rare-cell research and microarray-analysis.

A lensless on-chip fluorescent microscopy platform is demonstrated that can image fluorescent objects over an ultra-wide field-of-view of e.g., &#62;0.6-8 cm2 with &#60;4&#956;m resolution using a compressive sampling based decoding algorithm. Such a compact and wide-field fluorescent on-chip imaging modality could be valuable for high-throughput cytometry, rare-cell research and microarray-analysis.

Senza lenti microscopia a fluorescenza su un chip

On-chip lensless imaging in general aims to replace bulky lens-based optical microscopes with simpler and more compact designs, especially for ...

Ricerca

Bioingegneria

Silicon Metal-oxide-semiconductor Quantum Dots for Single-electron Pumping

As mass-produced silicon transistors have reached the nano-scale, their behavior and performances are increasingly affected, and often deteriorated, by quantum mechanical effects such as tunneling through single dopants, scattering via interface defects, and discrete trap charge states. However, progress in silicon technology has shown that these phenomena can be harnessed and exploited for a new class of quantum-based electronics. Among others, multi-layer-gated silicon metal-oxide-semiconductor (MOS) technology can be used to control single charge or spin confined in electrostatically-defined quantum dots (QD). These QD-based devices are an excellent platform for quantum computing applications and, recently, it has been demonstrated that they can also be used as single-electron pumps, which are accurate sources of quantized current for metrological purposes. Here, we discuss in detail the fabrication protocol for silicon MOS QDs which is relevant to both quantum computing and quantum metrology applications. Moreover, we describe characterization methods to test the integrity of the devices after fabrication. Finally, we give a brief description of the measurement set-up used for charge pumping experiments and show representative results of electric current quantization.

The fabrication process and experimental characterization techniques relevant to single-electron pumps based on silicon metal-oxide-semiconductor quantum dots are discussed.

Silicio metallico-ossido-semiconduttore Quantum Dots per singolo elettrone di pompaggio

As mass-produced silicon transistors have reached the nano-scale, their behavior and performances are increasingly affected, and often deteriorated, by ...

Ingegneria

Using Synchrotron Radiation Microtomography to Investigate Multi-scale Three-dimensional Microelectronic Packages

Synchrotron radiation micro-tomography (SR&#181;T) is a non-destructive three-dimensional (3D) imaging technique that offers high flux for fast data acquisition times with high spatial resolution. In the electronics industry there is serious interest in performing failure analysis on 3D microelectronic packages, many which contain multiple levels of high-density interconnections. Often in tomography there is a trade-off between image resolution and the volume of a sample that can be imaged. This inverse relationship limits the usefulness of conventional computed tomography (CT) systems since a microelectronic package is often large in cross sectional area 100-3,600 mm2, but has important features on the micron scale. The micro-tomography beamline at the Advanced Light Source (ALS), in Berkeley, CA USA, has a setup which is adaptable and can be tailored to a sample&#39;s properties, i.e., density, thickness, etc., with a maximum allowable cross-section of 36 x 36 mm. This setup also has the option of being either monochromatic in the energy range ~7-43 keV or operating with maximum flux in white light mode using a polychromatic beam. Presented here are details of the experimental steps taken to image an entire 16 x 16 mm system within a package, in order to obtain 3D images of the system with a spatial resolution of 8.7 &#181;m all within a scan time of less than 3 min. Also shown are results from packages scanned in different orientations and a sectioned package for higher resolution imaging. In contrast a conventional CT system would take hours to record data with potentially poorer resolution. Indeed, the ratio of field-of-view to throughput time is much higher when using the synchrotron radiation tomography setup. The description below of the experimental setup can be implemented and adapted for use with many other multi-materials.

For this study synchrotron radiation micro-tomography, a non-destructive three-dimensional imaging technique, is employed to investigate an entire microelectronic package with a cross-sectional area of 16 x 16 mm. Due to the synchrotron&#39;s high flux and brightness the sample was imaged in just 3 min&#160;with an 8.7 &#181;m spatial resolution.

L&#39;utilizzo delle radiazioni al sincrotrone microtomografia a indagare multi-scala Pacchetti microelettronici tridimensionali

Synchrotron radiation micro-tomography (SR&#181;T) is a non-destructive three-dimensional (3D) imaging technique that offers high flux for fast data ...

Laser-induced Forward Transfer of Ag Nanopaste

Over the past decade, there has been much development of non-lithographic methods1-3 for printing metallic inks or other functional materials. Many of these processes such as inkjet3 and laser-induced forward transfer (LIFT)4 have become increasingly popular as interest in printable electronics and maskless patterning has grown. These additive manufacturing processes are inexpensive, environmentally friendly, and well suited for rapid prototyping, when compared to more traditional semiconductor processing techniques. While most direct-write processes are confined to two-dimensional structures and cannot handle materials with high viscosity (particularly inkjet), LIFT can transcend both constraints if performed properly. Congruent transfer of three dimensional pixels (called voxels), also referred to as laser decal transfer (LDT)5-9, has recently been demonstrated with the LIFT technique using highly viscous Ag nanopastes to fabricate freestanding interconnects, complex voxel shapes, and high-aspect-ratio structures. In this paper, we demonstrate a simple yet versatile process for fabricating a variety of micro- and macroscale Ag structures. Structures include simple shapes for patterning electrical contacts, bridging and cantilever structures, high-aspect-ratio structures, and single-shot, large area transfers using a commercial digital micromirror device (DMD) chip.

We demonstrate the use of the Laser-induced forward transfer technique (LIFT) for the printing of high-viscosity Ag paste. This technique offers a simple, low temperature, robust process for non-lithographically printing microscale 2D and 3D structures.

Indotta da laser trasferimento di andata di Ag Nanopaste

Over the past decade, there has been much development of non-lithographic methods1-3 for printing metallic inks or other functional materials. Many of ...

Plasmonic Trapping and Release of Nanoparticles in a Monitoring Environment

Plasmonic tweezers use surface plasmon polaritons to confine polarizable nanoscale objects. Among the various designs of plasmonic tweezers, only a few can observe immobilized particles. Moreover, a limited number of studies have experimentally measured the exertable forces on the particles. The designs can be classified as the protruding nanodisk type or the suppressed nanohole type. For the latter, microscopic observation is extremely challenging. In this paper, a new plasmonic tweezer system is introduced to monitor particles, both in directions parallel and orthogonal to the symmetric axis of a plasmonic nanohole structure. This feature enables us to observe the movement of each particle near the rim of the nanohole. Furthermore, we can quantitatively estimate the maximal trapping forces using a new fluidic channel.

A microchip fabrication process that incorporates plasmonic tweezers is presented here. The microchip enables the imaging of a trapped particle to measure maximal trapping forces.

Plasmonico cattura e rilascio di nanoparticelle in un ambiente di monitoraggio

Plasmonic tweezers use surface plasmon polaritons to confine polarizable nanoscale objects. Among the various designs of plasmonic tweezers, only a few ...

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.

Multicolore fluorescenza Detection per Droplet microfluidica tramite fibre ottiche

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

Automated Delivery of Microfabricated Targets for Intense Laser Irradiation Experiments

Described is an experimental procedure that enables high-power laser irradiation of microfabricated targets. Targets are brought to the laser focus by a closed feedback loop that operates between the target manipulator and a ranging sensor. The target fabrication process is explained in detail. Representative results of MeV-level proton beams generated by irradiation of 600 nm thick gold foils at a rate of 0.2 Hz are given. The method is compared with other replenishable target systems and the prospects of increasing the shot rates to above 10 Hz are discussed.

A protocol is presented for automated irradiation of thin gold foils with high intensity laser pulses. The protocol includes a step-by-step description of the micromachining target fabrication process and a detailed guide for how targets are brought to the laser&#39;s focus at a rate of 0.2 Hz.

Consegna automatizzata di bersagli microfabbricati per intensi esperimenti di irradiazione laser

Described is an experimental procedure that enables high-power laser irradiation of microfabricated targets. Targets are brought to the laser focus by a ...

Multi-step Variable Height Photolithography for Valved Multilayer Microfluidic Devices

Microfluidic systems have enabled powerful new approaches to high-throughput biochemical and biological analysis. However, there remains a barrier to entry for non-specialists who would benefit greatly from the ability to develop their own microfluidic devices to address research questions. Particularly lacking has been the open dissemination of protocols related to photolithography, a key step in the development of a replica mold for the manufacture of polydimethylsiloxane (PDMS) devices. While the fabrication of single height silicon masters has been explored extensively in literature, fabrication steps for more complicated photolithography features necessary for many interesting device functionalities (such as feature rounding to make valve structures, multi-height single-mold patterning, or high aspect ratio definition) are often not explicitly outlined. 
Here, we provide a complete protocol for making multilayer microfluidic devices with valves and complex multi-height geometries, tunable for any application. These fabrication procedures are presented in the context of a microfluidic hydrogel bead synthesizer and demonstrate the production of droplets containing polyethylene glycol (PEG diacrylate) and a photoinitiator that can be polymerized into solid beads. This protocol and accompanying discussion provide a foundation of design principles and fabrication methods that enables development of a wide variety of microfluidic devices. The details included here should allow non-specialists to design and fabricate novel devices, thereby bringing a host of recently developed technologies to their most exciting applications in biological laboratories.

Multilayer microfluidic devices often involve the fabrication of master molds with complex geometries for functionality. This article presents a complete protocol for multi-step photolithography with valves and variable height features tunable to any application. As a demonstration, we fabricate a microfluidic droplet generator capable of producing hydrogel beads.

Multi-step altezza variabile fotolitografia per Valvolati multistrato microfluidici Devices

Microfluidic systems have enabled powerful new approaches to high-throughput biochemical and biological analysis. However, there remains a barrier to ...

High-resolution Volume Imaging of Neurons by the Use of Fluorescence eXclusion Method and Dedicated Microfluidic Devices

Volume is an important parameter regarding physiological and pathological characteristics of neurons at different time scales. Neurons are quite unique cells regarding their extended ramified morphologies and consequently raise several methodological challenges for volume measurement. In the particular case of in vitro neuronal growth, the chosen methodology should include sub-micrometric axial resolution combined with full-field observation on time scales from minutes to hours or days. Unlike other methods like cell shape reconstruction using confocal imaging, electrically-based measurements or Atomic Force Microscopy, the recently developed Fluorescence eXclusion method (FXm) has the potential to fulfill these challenges. However, although being simple in its principle, implementation of a high-resolution FXm for neurons requires multiple adjustments and a dedicated methodology. We present here a method based on the combination of fluorescence exclusion, low-roughness multi-compartments microfluidic devices, and finally micropatterning to achieve in vitro measurements of local neuronal volume. The high resolution provided by the device allowed us to measure the local volume of neuronal processes (neurites) and the volume of some specific structures involved in neuronal growth, such as growth cones (GCs).

Volume is an important parameter regarding physiological and pathological characteristics of cells. We describe a fluorescent exclusion method allowing full-field measurement of in vitro neuronal volume with sub-micrometric axial resolution required for the analysis of neurites and dynamic structures implied in neuronal growth.

Alta risoluzione Volume Imaging di neuroni nell'esclusione di uso di fluorescenza metodo e dedicato dispositivi microfluidici

Volume is an important parameter regarding physiological and pathological characteristics of neurons at different time scales. Neurons are quite unique ...

Neuroscienze

Microfabrication of Implantable Optics Integrated in a Microstructured Imaging Window for Advanced In Vivo Imaging

In the context of biomaterials and drug testing in animal models, this study presents a streamlined protocol for fabricating a novel implantable integrated imaging window. The micro-device comprises a sophisticated system of microlenses coupled with micro-scaffolds specifically designed for in vivo quantification of the immune response using advanced non-linear excitation microscopy. The protocol is based on two-photon polymerization (2PP) of the biocompatible photoresist SZ2080, which enables the fabrication of micro-scaffolds and micro-lenses in a continuous sequence to enhance manufacturing efficiency and precision. To further improve speed, accuracy, and structural integrity, a hybrid optics fabrication approach was implemented, involving the 2PP of the microlens outer shell followed by UV bulk crosslinking of the inner core. This innovative technique optimizes the optical properties of the microlenses while streamlining the production process. The resulting micro-device demonstrates high reproducibility and mechanical stability, making it an effective method for prototyping microscale optical systems for a range of biomedical applications.

This protocol describes the fabrication of an implantable integrated imaging window using 3D laser printing. The window consists of a system of microlenses coupled with micro-scaffolds. The method involves two-photon polymerization (2PP) of the biocompatible photoresist SZ2080 in a continuous sequence, optimizing manufacturing efficiency and alignment between the different components.

Laser-indotta Transfer Forward per Flip-chip Packaging di Dies Singolo

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