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-assisted Flip-chip Bonding
NOTE: There are three stages involved in realizing the LIFT-assisted flip-chip assemblies, namely-micro-bumping of the substrates using the LIFT technique, attaching the optoelectronic chips to the bumped substrates using thermo-compression flip-chip bonding method, and finally encapsulation of the bonded assemblies. Each of these stages is discussed in the following sections:
<ol>
	<li>Micro-bumping using LIFT:
	<ol>
		<li>For donor preparation, deposit a thin film of the donor material onto a laser-transparent carrier substrate. For this experiment, evaporate a 200 nm thick film of indium metal on top of glass carrier substrate with dimensions: 2 inch diameter x 0.05 cm thickness. 
		NOTE: Donor preparation method depends on the phase of the donor material, e.g., use evaporation and sputtering for solid phase donor materials and spin-coating and doctor-blading for liquid-phase donors.</li>
		<li>For receiver preparation, use glass substrates with dimensions of 5 x 5 x 0.07 cm3 as the receivers. Pattern these substrates with the metallic contact pads for bonding the OE chip and fan-out probing structures using photolithography. For this experiment, pattern 4 &#181;m thick Ni-Au bond pads and fan-out probing tracks onto glass receiver substrates.</li>
		<li>Next, place the donor in contact with the receiver and mount the donor-receiver assembly onto a computer controlled X-Y translation stage. 
		NOTE: Depending on the phase of the donor material (e.g., solid (indium) or liquid (ink/paste)) and its thickness, the donor and the receiver substrates are placed at an optimum separation that can be easily controlled (e.g., by using metallic spacers).</li>
		<li>Focus the incident laser beam at the carrier-donor interface employing an objective lens of 160 mm focal length and scan the beam (20 &#181;m spot size) across the donor substrate for transferring donor micro-bumps onto the receiver bond-pads. Use a picosecond laser source of 355 nm wavelength and 12 psec pulse duration to LIFT indium bumps onto the receiver bond-pads at a fluence of 270 mJ/cm2. 
		NOTE: The laser properties such as energy, no. of pulses, objective lens height, coordinates of the precise location on the receiver substrate for printing donor micro-bumps and the desired pattern to be transferred are accurately controlled by a computer program. Key experimental parameters (e.g., transfer fluence) need to be optimized in case of using another laser source.</li>
		<li>For thicker bumps move the donor to a fresh area and repeat step 1.1.4 several times. For example, repeat step 1.1.4 six times to get a stack of 6 indium bumps printed on top of each other for this experiment. The final LIFTed bumps have an average height of ~ 1.5 &#181;m and a diameter of 20 &#181;m (Figure 2). 
		NOTE: For these experiments the surface profile and thickness of the bumps were measured using an optical profilometer. It was examined that the bumps had a convex/dome morphology with an average thickness of 1.5 &#181;m, averaged over the bump diameter (as marked yellow in Figure 3). The reason for this is attributed to the fact that the donor melted in the laser irradiated zone and the transferred pellet then re-solidified upon reaching the receiver surface (Indium has a low melting point). The advantage of this is that it results in good adhesion of the printed bump to the VCSEL contact pads.</li>
	</ol>
	</li>
	<li>Chip to substrate thermo-compression bonding (Figures 4-6):
	<ol>
		<li>Use a semiautomatic flip-chip bonder for bonding the optoelectronic chips to the bumped substrates.</li>
		<li>Load the bumped receiver and the chip to be bonded onto their respective vacuum plates of the bonder. Place the chip in a flipped position, i.e., with its active area facing down.</li>
		<li>Use a suitable pick-up tool and align it on the center of the chip. Use a needle-shaped tool as shown in Figure 5. Next, pick the chip using this pick-up tool.</li>
		<li>Align the chip bond-pads with the corresponding contact pads on the receiver substrate using a camera-alignment system.</li>
		<li>Once aligned place the chip on the substrate.</li>
		<li>Apply heat (~ 200 &#176;C) and pressure (12.5 gf/bump) simultaneously to realize chip to substrate electrical and mechanical interconnections.</li>
	</ol>
	</li>
	<li>Encapsulation of the bonded assemblies (Figures 4-6):
	<ol>
		<li>Dispense an optically transparent adhesive around the edges of the bonded assembly using a syringe needle. The encapsulation increases the mechanical reliability of the bonded assemblies. Use a single component UV curable adhesive such as NOA 86 for encapsulating the bonded chips.</li>
		<li>Cure the adhesive using a UV lamp for ~ 30 sec.</li>
	</ol>
	</li>
</ol>
2. Characterization of the Bonded Vertical-cavity Surface-emitting Lasers (VCSELs)
NOTE: After fabrication the next step is to evaluate the electro-optical performance of the bonded assemblies. The light-current-voltage (LIV) curves of the devices are recorded post-bonding using a probe station. The following steps are involved for the testing:
<ol>
	<li>Place the flip-chip bonded device onto a custom-made transparent stage. The stage has a hole drilled in the center for easy access to the light emitted by the VCSELs.</li>
	<li>Place a photodetector (PD) underneath the transparent stage and align its active area with the bonded chip using a microscope.</li>
	<li>Precisely position the probing needles on the Ni-Au probing pads using a microscope.</li>
	<li>Inject up to 10 mA of current and measure the voltage drop across the VCSEL and the light emitted by it using a current/voltage source-meter unit and a power meter respectively.</li>
</ol>

<ol>
	<li>Davis, E., Harding, W., Schwartz, R., Coring, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Solid+logic+technology:+versatile,+high+performance+microelectronics.">Solid logic technology: versatile, high performance microelectronics.</a> IBM J. Res. Develop. 8, 102-114 (1964).</li><li>Bigas, M., Cabruja, E., Lozano, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bonding+techniques+for+hybrid+active+pixel+sensors+(HAPS).">Bonding techniques for hybrid active pixel sensors (HAPS).</a> Nucl. Instrum. Methods Phys. Res. A. 574 (2), 392-400 (2007).</li><li>Bohandy, J., Kim, B. F., Adrian, F. 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The authors have nothing to disclose.

In this paper, we have demonstrated thermo-compression flip-chip bonding of single VCSEL chips using a laser based direct-write technique called LIFT. The assembly fabrication steps involved printing of the micro-bumps of indium onto the substrate contact pads using the LIFT technique. This was followed by thermo-compression flip-chip bonding of VCSEL chips to the bumped substrates and finally their encapsulation.
Electrical, optical and mechanical reliability of the LIFT-assisted bonded chips...

Laser-induced Forward Transfer (LIFT) is a versatile direct-write additive manufacturing method for single-step pattern definition and material transfer with micron and sub-micron-resolution. In this paper, we report the use of LIFT as a bumping technique for flip-chip packaging of vertical-cavity surface-emitting lasers (VCSELs) on a chip-scale. Flip-chip is a key technology in system packaging and integration of electronic and optoelectronic (OE) components. In order to achieve dense integration of components fine pitch bonding is essential. Although fine pitch bonding has been demonstrated by some of the standard techniques but there is a void in terms of combining together the other important features such as flexibility, cost-effectiveness, speed, accuracy and low processing temperature. In order to meet these requirements we demonstrate LIFT-assisted thermo-compression bonding method for fine pitch bonding of OE components.
In LIFT, a thin film of the material to be printed (referred to as the donor) is deposited onto one face of a laser-transparent support substrate (referred to as the carrier). Figure 1 depicts the basic principle of this technique. An incident laser pulse of sufficient intensity is then focused at the carrier-donor interface that provides the propelling force required to forward transfer the donor pixel from the irradiated zone onto another substrate (referred to as the receiver) placed in close proximity.
LIFT was first reported in 1986 by Bohandy as a technique to print micron-sized copper lines for repairing damaged photo-masks3. Since its first demonstration this technique has gained significant interest as a micro-nano fabrication technology for controlled patterning and printing of a wide range of materials such as ceramics4, CNTs5, QDs6, living cells7, graphene8, for diverse applications such as bio-sensors9, OLEDs10, optoelectronic components 11, plasmonic sensors12, organic-electronics13 and flip-chip bonding14,15.
LIFT offers several advantages over the existing flip-chip bumping and bonding techniques such as simplicity, speed, flexibility, cost-effectiveness, high-resolution and accuracy for flip-chip packaging of OE components.

<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) packaging is a key technology for realizing high performance, ultra-miniaturized and high-density circuits in the micro-electronics industry. In this technique the chip and/or the substrate is bumped and the two are bonded via these conductive bumps. Many bumping techniques have been developed and intensively investigated since the introduction of the FC technology in 19601 such as stencil printing, stud bumping, evaporation and electroless/electroplating2. Despite the progress that these methods have made they all suffer from one or more than one drawbacks that need to be addressed such as cost, complex processing steps, high processing temperatures, manufacturing time and most importantly the lack of flexibility. In this paper, we demonstrate a simple and cost-effective laser-based bump forming technique known as Laser-induced Forward Transfer (LIFT)3. Using the LIFT technique a wide range of bump materials can be printed in a single-step with great flexibility, high speed and accuracy at RT. In addition, LIFT enables the bumping and bonding down to chip-scale, which is critical for fabricating ultra-miniature circuitry.

Figure 7 shows a typical LIV curve that was recorded from one of the many flip-chip bonded VCSEL chips. A good match between the measured optical power to the supplier quoted values indicated successful functioning of the bonded devices post-bonding. The curves were also recorded prior- and post-encapsulation and upon comparison it was verified that the encapsulant had no affect on the chip functionality (as shown in Figure 7). Also, a comparison between the I-V curves recorded for the f...

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

We demonstrate the use of the Laser-induced Forward Transfer (LIFT) technique for flip-chip assembly of optoelectronic components. This approach provides a simple, cost-effective, low-temperature, fast and flexible solution for fine-pitch bumping and bonding on chip-scale for achieving high-density circuits for optoelectronic applications.

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

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Engineering

12.3K Views.  Ghent University-imec.  We tonen het gebruik van de Laser-induced Forward Transfer (LIFT) techniek voor flip-chip assemblage van opto-elektronische componenten. Deze aanpak biedt een eenvoudige, kosteneffectieve, lage temperatuur, snelle en flexibele oplossing voor fijn-pitch stoten en hechting op chip-schaal voor het bereiken van een hoge dichtheid circuits voor opto-elektronische toepassingen. 

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.

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

Bioengineering

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.

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

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.

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.

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.

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.

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.

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.

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.

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

Neuroscience

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

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