Victor J Cadarso

• PH.D.
• Group Leader at Monash University (Australia)

STUDY QUESTION Is it feasible to safely determine metabolic imaging signatures of nicotinamide adenine dinucleotide [NAD(P)H] associated auto-fluorescence in early embryos using a light-sheet on-a-chip approach? SUMMARY ANSWER We developed an optofluidic device capable of obtaining high-resolution 3D images of the NAD(P)H autofluorescence of live...

Study question Is it feasible to safely determine metabolic imaging signatures to measure nicotinamide adenine dinucleotide (NADH) associated auto-fluorescence in early embryos using a scalable lab-on-a-chip approach? Summary answer We developed an optofluidic device capable of non-invasively obtain high-resolution 3D images of the metabolic activ...

Having a system capable of obtaining high resolution, quantitative, subcellular information of individual live cells through imaging, while minimizing cell damage, is of great importance in many fields of research. In recent years, optofluidic light-sheet fluorescent microscopy (LSFM) has emerged as a powerful tool providing a low photo-toxic imagi...

Hypothesis: Lyotropic liquid crystals (LLC) and their phase transformations in response to stimuli have gathered much interest for controlled and 'on-demand' drug applications. Bulk methods of preparation impose limitations on studying the transformations, especially induced by compositional changes, such as enzymatic changes to lipid structure. H...

Having a system capable of obtaining high resolution, quantitative, subcellular information of indi- vidual live cells through imaging, while minimizing cell damage, is of great important in many fields of research. In recent years, optofluidic light-sheet fluorescent microscopy (LSFM) has emerged as a powerful tool providing a low photo-toxic imag...

Microneedle-based wearable sensors offer an alternative approach to traditional invasive blood-based health monitoring and disease diagnostics techniques. Instead of blood, microneedle-based sensors target the skin interstitial fluid (ISF), in which the biomarker type and concentration profile resemble the one found in the blood. However, unlike bl...

Surface acoustic wave (SAW) driven devices typically employ polymeric microfluidic channels of low acoustic impedance mismatch to the fluid in contact, to allow precise control of the wave field. Several of these applications, however, can benefit from the implementation of an acoustically reflective surface at the microfluidic channel's ceiling to...

Standard methods, such as plate counting, to detect bacteria in samples where only small volumes and low concentrations are available, will result in a negative detection, unless additional enriching steps, such as culturing, are used. However, these are laborious and time consuming, which may prevent their effective application to time sensitive s...

The ability to create complex three-dimensional cellular models that can effectively replicate the structure and function of human organs and tissues in vitro has the potential to revolutionize medicine. Such models could facilitate the interrogation of developmental and disease processes underpinning fundamental discovery science, vastly accelerat...

Background: Developing non-invasive methods that are reliable to assess embryo quality has been a significant aim for assisted reproductive technologies. Changes in metabolic activity could lead to abnormal embryo development and implantation potential which could be potentially predicted by incorporating non-invasive measurements of metabolism. Me...

The precise manipulation of individual cells is a key capability for the study of single cell physiological characteristics or responses to stimuli. Currently, only large cell populations can be transferred with certainty using expensive and laborious flow cytometry platforms. However, when approaching small populations of cells, this task becomes...

Sperm motility is a significant predictor of male fertility potential and is directly linked to fertilization success in both natural and some forms of assisted reproduction. Sperm motility can be impaired by both genetic and environmental factors, with asthenozoospermia being a common clinical presentation. Moreover, in the setting of assisted rep...

Microbial contamination in in vitro cell culture technologies is a common problem endangering the reliability of the collected data and biosafety of the biological products. Conventionally, microbial contamination can be detected by monitoring the pH and turbidity of cell culture media when using light microscope and/or molecular probes. These meth...

High-Throughput Screening In article number 2100881, Nicolas H. Voelcker, Jessica E. Frith, Victor J. Cadarso, and co-workers demonstrate a novel approach to imprint micro and nanoscaled topographical features into conventional cell cultureware, facilitating its compatibility with standard biological techniques. This enables high-throughput screeni...

Cells are able to perceive complex mechanical cues across both the micro‐ and nanoscale which can influence their development. Whilst causative effects between surface topography and cellular function can be demonstrated, the variability in materials used in this screening process makes it difficult to discern whether the observed phenotypic change...

Cells are able to perceive complex mechanical cues from their microenvironment, which in turn influences their development. Although the understanding of these intricate mechanotransductive signals is evolving, the precise roles of substrate microtopography in directing cell fate is still poorly understood. Here, UV nanoimprint lithography is used...

Parkinson`s disease (PD) is a progressive neurodegenerative disorder involving dopaminergic neurons from the substantia nigra. The loss of dopaminergic neurons results in decreased dopamine (DA) release in the striatum and thus impaired motor functions. DA is one of the key neurotransmitters monitored for the diagnosis, and during the progression a...

Miniaturization of sensing technology has led to the development of multifunctional micro total analysis systems (µTAS) that benefit from microfluidics technology. Optical sensing is one of the most commonly used sensing approaches integrated into µTAS devices and features high sensitivity and low detection limits. Different materials have been use...

The number of studies conducted about nonenzymatic electrochemical sensors has increased in recent years due to the development of more stable and robust electrodes using noble metals. One of the key aspects for achieving high sensing performance including detection limit and sensitivity is the design of electrode architecture. Herein, we report a...

Nowadays, there is increasing number of electrochemical biosensors which utilize chitosan (Ch); as an enzyme immobilization matrix, and conductive nanomaterials; as electron carriers improving sensitivity of the biosensor. However, the challenge these sensors face is the lack of uniform dispersion of nanomaterials throughout the Ch film, which can...

Rapid progress in protein crystallography techniques at X-ray free electron lasers (X-FELs) requires the development of new methods for sample delivery. Recording dynamic changes in protein structures is one of the aims. To assess protein dynamics, sample holders for crystallography need to become active devices, providing possibilities to induce i...

Patterning of diamond-like carbon (DLC) and DLC:metal nanocomposites is of interest for an increasing number of applications. We demonstrate a nanoimprint lithography process based on silicon containing thermoplastic resist combined with plasma etching for straightforward patterning of such films. A variety of different structures with few hundred...

Different methods capable of developing complex structures and building elements with high-aspect-ratio nanostructures combined with microstructures, which are of interest in nanophotonics, are presented. As originals for subsequent replication steps, two families of masters were developed: (i) 3.2 μm deep, 180 nm wide trenches were fabricated by s...

A novel lab-on-a-chip (LoC) device based on the combination of an optofluidic component and a polymeric substrate with a smart surface reacting on UV light is presented for the first time. In the dark or under visible light, the surface containing an enzyme fragment is almost inert and visible (VIS) light (i.e. @ 635 nm) propagating through the opt...

Copolymer brushes, composed of glycidyl methacrylate and a furan-protected maleimide-containing monomer, were grafted from radical initiators at the surface of irradiation-activated fluoropolymer foils. After post-polymerization modification with enzymatically active microperoxidase-11 and photochromic spiropyran moieties, the polymer brushes catal...

Stimuli-responsive materials undergo physicochemical, and/or structural changes when a specific actuation is applied. They are heterogeneous composites, consisting of a non-responsive matrix where functionality is provided by the filler. Surprisingly, the synthesis of Polydimethylsiloxane (PDMS)-based stimuli-responsive elastomers (SRE) has seldoml...

Therapeutic drug monitoring (TDM) typically requires painful blood drawn from patients. We propose a painless and minimally-invasive alternative for TDM using hollow microneedles suitable to extract extremely small volumes (<1 nL) of interstitial fluid to measure drug concentrations. The inner lumen of a microneedle is functionalized to be used as...

Patterning of diamond-like carbon (DLC) and DLC:metal nanocomposites is of interest for an increasing number of applications. We demonstrate a nanoimprint lithography process based on silicon containing thermoplastic resist combined with plasma etching for straightforward patterning of such films. A variety of different structures with few hundred...

Photonic nanofences consisting of high aspect ratio polymeric optical subwavelength waveguides have been developed for their application into photonic sensing devices. They are up to millimeter long arrays of 250 nm wide and 6 µm high ridges produced by an advanced lithography process on a silicon substrate enabling their straightforward integratio...

Plano-convex microlens arrays of organic-inorganic polymers with tailored optical properties are presented. The fine-tuning of each microlens within an array is achieved by confining inkjet printed drops of the polymeric ink onto pre-patterned substrates. The lens optical properties are thus freely specified, and high numerical apertures from 0.45...

Subwavelength photonic nanofences are able to guide light with intense evanescent fields, up to above 90% of the coupled light, and with low losses (∼12 dB/mm). This presents them as ideal candidates for sensing applications.

Magnetically-actuable, polymer-based variable optical attenuators (VOA) are presented in this paper. The design comprises a cantilever which also plays the role of a waveguide and the input/output alignment elements for simple alignment, yet still rendering an efficient coupling. Magnetic properties have been conferred to these micro-opto-electrome...

A polymer-based Micro-optoelectromechanical system (MOEMS) design as a Variable Optical Attenuator (VOA) is presented. It consists on a SU-8 quad-beam structure containing a suspended waveguide aligned to input/output fiber optics. Actuation is achieved by defining photonic-heat transition regions at the anchoring of the mechanical beams. Such actu...

This work describes the use of a piezo-actuated inkjet print head with a nozzle aperture of 50 mu m to obtain picoliter drops of different model ionic liquids (ILs). A theoretical analysis of the microdrop generation of three model ILs is confirmed by experiments. The inkjet print process was optimized to enable a stable and reproducible drop eject...

Structuring SU-8 based superparamagnetic polymer composite (SPMPC) containing Fe3O4 nanoparticles by photolithography is limited in thickness due to light absorption by the nanoparticles. Hence, obtaining thicker structures requires alternative processing techniques. This paper presents a method based on inkjet printing and thermal curing for the f...

This paper reports and compares the implementation of magnetic variable optical attenuators (M-VOA) by two fabrication strategies. In the first case, a two-layer structure containing a non-doped polydimethylsiloxane (PDMS) layer on a magnetic PDMS (M-PDMS) layer is fabricated by soft lithography (SLT). M-PDMS is obtained by doping PDMS with differe...

A volume hologram recorded with a lens array is proposed as a color transflective screen for Head Worn Display (HWD) systems. Design, fabrication as well as proof of concept are reported. Light from a single MEMS-based projector is efficiently diffracted towards the eye with an angular spread given by the numerical aperture of the lenses forming th...

We present the fabrication and characterization of large arrays of inkjet printed superparamagnetic polymer composite (SPMPC) hemispherical microstructures. SPMPCs are appealing for applications in microsystems and nanorobotics due to the added functionality of polymers and the significant magnetic attributes of embedded nanostructures. SPMPC-based...

Nanogaps or sharp protrusions has been proved useful for surface enhanced Raman scatting (SERS) in single-molecule sensing and a low cost method for fabricating SERS active substrate with these naonstructures is very important for practical applications ...

The challenging fabrication of sub-100-nm structures with high aspect ratio by UV-nanoimprint lithography (NIL) is addressed in this work. Thermal shrinkage is induced by cooling the structures below room temperature to avoid the issues commonly arising during the release of the polymeric nanostructures from the master. The UV-NIL has been performe...

Planar lithography techniques are not effective for precise fabrication of microdevices with hemispherical shapes. Drop-on-demand (DOD) inkjet printing (IJP) of photo-curable ink is a more appropriate fabrication approach as it takes advantage of the surface tension as well as of the delivery of a well-defined ink volume. Described is a DOD IJP tech...

Fluid-mediated self-assembly is one of the most promising routes for assembling and packaging smart microsystems in a scalable and cost-efficient way. In this work the pairwise fluidic self-assembly of 100 μm-sized SU-8 cylinders is studied with respect to two driving mechanisms: capillary forces at the liquid-air interface and hydrophobic effect w...

We present the first experimental realization of a light spectral filter based on the spatial adiabatic passage technique. We demonstrate that a fully integrable CMOS-compatible system of three coupled identical total internal reflection silicon oxide waveguides with variable separation along their propagation direction can be used simultaneously a...

A moiré is an interference pattern that appears when two different periodic structures are overlaid. The image created is extremely sensitive to small variations in the original layers and is thus very interesting for anti-counterfeit protection. We present a microfabricated 1D moiré enabling complex high-resolution patterns as a significantly impr...

Moirés have been increasingly applied to create novel security features typically implemented by means of printing techniques, which achieve a resolution up to 2000 dpi. However, this resolution is not sufficient to effectively prevent counterfeits by desktop scanners and printers. In this paper we propose and demonstrate the design and cost-effici...

This paper presents the design, fabrication and characterization of all-optical polymer-based Micro-optoelectromechanical system (MOEMS) Variable Optical Attenuator (VOA). It consists of an SU-8 quad-beam structure and a suspended waveguide aligned to input/output fiber optics. Actuation is achieved by defining dye-doped SU-8 structures on the mech...

The fabrication of precise hemispherical shape is challenging with standard planar lithography techniques. A suitable alternative is the fabrication by inkjet printing. This paper presents a method based on drop-on-demand inkjet printing on pre-patterned silicon substrates allowing the controlled fabrication of SU-8 hemispherical cup-like structure...

In this work a portable analytical biosensor for real-time extracellular monitoring of released hydrogen peroxide (H2O2 ) is presented. The biosensor is based on the optical detection of the cytochrome c (cyt c) oxidation state. The setup consists of an integrated microscope combined with a compact spectrometer. The light being absorbed by cyt c is...

A volume hologram recorded with a lens array is proposed as a transflective screen for Head Worn Display (HWD) systems. Design, fabrication as well as proof of concept are reported. Light from a projection system, with similar properties to one mounted on the side of an eyewear, is efficiently diffracted towards the eye with an angular spread given...

This paper reports the implementation of magnetic variable optical attenuators (M-VOA) by soft lithography (SLT) and using polydimethylsiloxane (PDMS) as constituent material. Two different fabrication protocols are used and compared. In the first case, a two-layer structure containing a clean PDMS layer on a magnetic PDMS (M-PDMS) layer is fabrica...

We present the characterization of dyed doped/modified Epocore resist (Microresist Technology, Germany) with three commercially-available dyes (Proquimac Color, Spain). After being doped with lilac, red and yellow dyes in a 1:2500 ratio (dye:Epocore, w:w), an exposure dose test was performed. The obtaining lithographic performance is similar to the...

A novel combination of ink-jet printing (UP) and micro-transfer moulding (mu-TM) for high-resolution, heterogeneous material microstructuring is demonstrated. First, UP is used to accurately fill the microcavities in an elastomeric mould, thus avoiding the use of spin coating or direct casting with a noticeable reduced material waste. Second, a mu-...

The one-step room-temperature micropatterning of a fluorophore-doped xerogel material on silicon oxide substrates is reported. The organo-alkoxysilane precursors and organic fluorescent dyes, as well as the polymerization experimental conditions, were tailored in order to obtain a highly homogeneous transparent material suitable for photonic applic...

In this paper a nano-molding process using a nature-created master is demonstrated. The eye of night moth Agotis exclamationis having 100 nm-scale structures on a curved surface is used as biomimetic master mold from which nanostructures are replicated onto a flat substrate. Suitable conditions of this simple and cost-efficient process allows for m...

Well-controlled spherical microstructures open new possibilities for several MEMS devices, such as hemispherical microfluidic channels or micro-optical elements. However, machining of micro-spherical shapes has proven to be difficult with conventional planar micro-fabrication processes. This paper presents a fabrication method allowing the fabricat...

A fully complementary metal–oxide–semiconductor-compatible adiabatic passage of light in the visible range is presented in this letter. We experimentally show that a system of three total internal reflection waveguides, which has been defined by using non-stoichiometric silicon oxide, allows a highly efficient transfer of light between the outermos...

In this work the combined use of direct laser writing (DWL) and a new epoxy material (mr-DWL) for fast prototyping of μTAS devices is demonstrated. The fabrication process is based in the use of DWL to manufacture epoxy-based masters without using any mask, and replicate them into PDMS. A total processing time of less than 12h from the design to th...

Ink-jet printing of optical ink over SU-8 pillars is here proposed as a technology for obtaining microlenses with shape control. To demonstrate the flexibility of this method, microlenses with five different contour shapes (ranging from circular and elliptical to toric or more advanced geometries) have been fabricated. Furthermore, the optical prop...

Rhodamine B and Alexa Fluor 430 fluorophores have been used as doping agents for xerogel waveguides defined over an antiresonant (ARROW) filter. This configuration has a significant level of integration, since it merges the waveguide, the light emitter and the filter in a single photonic element. Different technologies have been combined for their...

The development of high aspect ratio (AR) structures is of great interest in several fields such as micro-electro-mechanical systems or microfluidics. In this note we present a new processing method of epoxy materials based on direct write laser (DWL) scanning exposure. In this work, we describe the application of this technique for fast prototyping,...

Microalgalcells were entrapped within two different sol–gel silica matrices with the aim of carrying out viability studies and developing active phases for sensor development. The first sol–gel system, based on methacryloxypropyltrimethoxysilane (MAPTS) and tetramethoxysilane (TMOS) monomers, was able to entrap lyophilized Chlorella vulgaris and An...

A system of two solid microlenses with uncoupled optical properties is presented. This structure has been designed in order to have one lens as a reference, while the other one can be mechanically tuneable. The reference lens presents a diameter of 2 μm and it is placed in the optical axis of the mechanically tuneable lens, which has a diameter of...

We describe design and miniaturization of a polymeric optical interface for flow monitoring in biomicrofluidics applications based on polydimethylsiloxane technology, providing optical transparency and compatibility with biological tissues. Design and ray tracing simulation are presented as well as device realization and optical analysis of flow dy...

We have developed a monolithically integrated and highly sensitive polydimethylsiloxane (PDMS) based biosensor that includes microfluidics and photonics in a single-mask process. Optically, the system consists of selfalignment structures for fiber optics positioning, microlenses (to correct the divergence of the emitted light) and air micromirrors...

Taking advantage of the poly(dimethyl siloxane) (PDMS) optical and structural properties, it is possible to develop a highly sensitive PDMS-based photonic lab on a chip, which has been named Propagating Multiple Internal Reflection (PMIR) system. For the application in this system, the surface of PDMS was chemically modified and then Horseradish Pe...

This work shows the design and fabrication of microstructures using an organic-inorganic polymer xerogel material doped with several fluorophores and micromolding in capillaries soft lithography technique (MIMIC). This technique enabled the development of a variety of microstructures with an aspect ratio of up to 1:10 (width:height) in turn showing...

Poly(dimethylsiloxane) (PDMS) has been considered for the first time for defining cantilever-based microoptoelectromechanical systems (MOEMS) by ways of soft lithography. The systems shown have a high degree of integration, comprising cantilever-waveguides, lenses, self alignment systems and seismic mass. The very low Young's modulus allows definin...

In this work it is shown how the inclusion of the air mirrors allows the implementation of a highly sensitive absorbance based biosensor based on Multiple Internal Reflection (MIR). They have been fabricated in a single-mask step and replicated in Poly(dimethylsiloxane) (PDMS) using soft lithographic techniques. Experimental results confirm the ray...

This paper presents the design, simulation, fabrication and characterization of a silicon hollow waveguide-based full-field absorbance biosensor and its application for the detection of hydrogen peroxidase (H2O2) using a peroxidase enzyme as a model recognition element. Such a system merges into one single microstructure the transducer (waveguide)...

The optical and structural properties of poly(dimethylsiloxane) (PDMS) are considered to define disposable cantilever-based micooptoelectromechanical systems (MOEMS) by ways of soft lithography and with a high degree of monolithic integration. The very low Young's modulus of this material relaxes the dimensions' requirements, being then possible to...

The design, simulation, fabrication and characterization of two SU-8 based microoptoelectromechanical systems (MOEMS) are presented in this paper: an optical accelerometer and a variable optical attenuator (VOA). Both devices consist on a quad-beam polymer structure and can be fabricated with a simple technology, requiring only two photolithographi...

A full-field generic photonic biosensor approach, which relies on a bio-doped polymeric strip waveguide configuration, is described. We show the potential of tailor-made hybrid polymeric materials prepared by sol-gel technology for the fabrication of ultra-compact biosensor devices, where both the transducer and the recognition elements are merged...

The first absorbance biosensor based on pure silicon hollow integrated waveguides is presented in this work. With the use of horseradish peroxidase (HRP) as a model recognition element, an enzymatic sensor for the measurement of hydrogen peroxide was fabricated, numerically simulated, and experimentally characterized. Waveguides with widths ranging...

A ray tracing simulation method for integrated optics hollow waveguides has been developed. This method has been tested on Silicon waveguides with good results, providing a suitable design tool for new devices using this type of waveguides. The simulations allow the design of new guiding structures based on hollow waveguides, like input tapers to r...

The design, simulation, fabrication and characterization of 3-D modulable micro-optical system based on poly-dimethilsiloxane (PDMS) are presented in this paper. This system consists on two uncoupled PDMS lenses with different diameter (2 and 10 µm). Under stretching conditions, the dimensions of the small lens are not modified, whereas the geometr...

Organic–inorganic silicon-based polymers can be tailor-made to obtain materials with mechanical, chemical, optical, or electric properties that suit a great variety of applications and are compatible with microfabrication technologies. Herein, this work reports on the one-step processing of microstructures of a sol–gel polymeric material on flat su...

This paper describes the simulation, fabrication and characterization of silicon-based rectangular hollow waveguides. Numerical evaluation of such structures has been done using both modal propagation and ray tracing, low total losses and multimodal behavior, even for small core sizes, are predicted. Since light propagation in rectangular hollow wa...

This contribution deals with the numerical simulation of SU-8 devices. We introduced a new integrated polymer optical accelerometer based on intensity modulation formed by a SU-8 polymer structure. The SU-8 polymer is used as structural material but also as optical waveguide. It consists of one mass adjoined to four mechanical beams, all of them ma...

Organic-inorganic silicon-based polymers can be tailor made in order to get materials with mechanical, chemical, optical or electric properties that suit a great variety of applications and are compatible with microfabrication technologies1. Herein, this work reports on the one-step processing of photonic microstructures of a sol-gel polymeric mate...

Deflection of a microcantilever caused by any kind of biochemical reaction occurring on its surface can be detected with subangstrom resolution if an appropriate detection technique is exploited. This kind of transducers has become widely used in biological research since a few years ago. Usually, for the readout of the nanomechanical response of t...

This paper presents the optimization and characterization of SU-8 quad beam optical accelerometers based on intensity modulation. An applied acceleration causes a misalignment between three waveguides, resulting in variation of losses. Mechanical simulations have focused on the evaluation of sensitivity and the design of a robust junction between t...

This paper presents the design, fabrication and characterization of polymer microoptoelectromechanical systems (MOEMS). An optical accelerometer and a variable optical attenuator (VOA) based on SU-8 are presented. Both devices consist on a quad-beam polymer structure and can be fabricated with a simple technology, requiring only two photolithograph...

In this letter, we take advantage of the high coefficient of thermal expansion (CTE) of a chemically amplified, epoxy-based negative polymer (SU-8) to define a low-power consumption polymeric variable optical attenuator that combines the working principles of microoptoelectromechanical systems and photonic lightwave circuits. The SU-8 symmetric str...

This contribution deals with the optimization of a new SU-8 optical accelerometer. Microaccelerometers became large-scale production devices the last 90's. Several working principles have been applied for acceleration sensing. However, most of them suffer from high cross-sensitivity to electromagnetic interferences (EMI) and they cannot be used und...

The design, simulation, fabrication, and characterization of quad-beam polymer optical accelerometers is presented in this paper. An applied acceleration causes a misalignment between the waveguides that comprise the structure. Two different geometries with different beam widths have been tested. Both of them show high mechanical and optical sensit...

Butt coupled optical waveguides are well known in integrated optics by high sensitivity of energy transfer to their misalignment with respect to each other. This might be detrimental if efficient and firm coupling from one light guide to another is needed, for example, coupling from a fiber to a waveguide on chip. However, this phenomena is efficie...