Electrical Stimulation of Trigeminal Nerve at the Anterior Nasal Septum in Healthy Individuals and Patients With Olfactory Dysfunction.

Background: The intranasal trigeminal system contributes to the sense of smell. Its integrity in olfactory dysfunction (OD) may be crucial for future treatments. This study assessed trigeminal sensitivity in healthy individuals and patients with OD of different etiologies using electrical stimulation of the nasal mucosa.

Additive manufacturing of water-soluble 3D micro molds for complex-shaped lipid microparticles.

Micro and nanoparticles made from polymers, metals, ceramics, and lipids are crucial for biomedical devices, energy storage, and electronics. Traditional fabrication methods like grinding, milling, and emulsification result in monolithic shapes and heterogeneous sizes. To improve shape control, techniques such as photolithography, inkjet printing (IJP), and molding are employed.

Devices for the electrical stimulation of the olfactory system: A review.

The loss of olfactory function has a profound impact on quality of life, affecting not only sensory perception but also memory, emotion, and overall well-being. Despite this, advancements in olfactory prostheses have lagged significantly behind those made for vision and hearing restoration. This review offers a comprehensive analysis of the current state of devices for electrical stimulation of the olfactory system.

Hot topic: Mapping of the human intranasal mucosal thermal sensitivity: A clinical study on thermal threshold and trigeminal receptors.

Introduction: The olfactory and trigeminal system are closely interlinked. Existing literature has primarily focused on characterizing trigeminal stimulation through mechanical and chemical stimulation, neglecting thermal stimulation thus far. The present study aimed to characterize the intranasal sensitivity to heat and the expression of trigeminal receptors (transient receptor potential channels, TRP).

Electrowriting of SU-8 Microfibers.

As microfiber-based additive manufacturing (AM) technologies, melt electrowriting (MEW) and solution electrowriting (SEW) have demonstrated efficacy with more biomedically relevant materials. By processing SU-8 resin using MEW and SEW techniques, a material with substantially different mechanical, thermal, and optical properties than that typically processed is introduced. SU-8 polymer is temperature sensitive and requires the devising of a specific heating protocol to be properly processed.

Combining thermal scanning probe lithography and dry etching for grayscale nanopattern amplification.

Grayscale structured surfaces with nanometer-scale features are used in a growing number of applications in optics and fluidics. Thermal scanning probe lithography achieves a lateral resolution below 10 nm and a vertical resolution below 1 nm, but its maximum depth in polymers is limited. Here, we present an innovative combination of nanowriting in thermal resist and plasma dry etching with substrate cooling, which achieves up to 10-fold amplification of polymer nanopatterns into SiO without proportionally increasing surface roughness.

Microfluidic device combining hydrodynamic and dielectrophoretic trapping for the controlled contact between single micro-sized objects and application to adhesion assays.

The understanding of cell-cell and cell-matrix interactions receptor and ligand binding relies on our ability to study the very first events of their contact. Of particular interest is the interaction between a T cell receptor and its cognate peptide-major histocompatibility complex. Indeed, analyzing their binding kinetics and cellular avidity in large-scale low-cost and fast cell sorting would largely facilitate the access to cell-based cancer immunotherapies.

Aperture-Controlled Fabrication of All-Dielectric Structural Color Pixels.

While interference colors have been known for a long time, conventional color filters have large spatial dimensions and cannot be used to create compact pixelized color pictures. Here we report a simple yet elegant interference-based method of creating microscopic structural color pixels using a single-mask process using standard UV photolithography on an all-dielectric substrate. The technology makes use of the varied aperture-controlled physical deposition rate of low-temperature silicon dioxide inside a hollow cavity to create a thin-film stack with the controlled bottom layer thickness.

Impedance spectroscopy of the cell/nanovolcano interface enables optimization for electrophysiology.

Volcano-shaped microelectrodes have demonstrated superior performance in measuring attenuated intracellular action potentials from cardiomyocyte cultures. However, their application to neuronal cultures has not yet yielded reliable intracellular access. This common pitfall supports a growing consensus in the field that nanostructures need to be pitched to the cell of interest to enable intracellular access.

Rapid exocytosis kinetics measured by amperometry within volcano microelectrodes.

For over 30 years, carbon fiber microelectrodes have been the gold standard for measurements related to exocytosis and more generally to the processes taking place at the synaptic level. However, this method has a low throughput and molecules can escape detection due to the featureless nature of the planar microelectrodes it uses. Here we present a new electrochemical sensor that addresses these limitations.

High precision, high throughput generation of droplets containing single cells.

The Poisson limit is a major problem for the isolation of single cells in different single-cell technologies and applications. In droplet-based single-cell assays, a scheme that is increasingly popular, the intrinsic randomness during single-cell encapsulation in droplets requires most of the created droplets to be empty, which has a profound impact on the efficiency and throughput of such techniques, and on the predictability of the combinatory droplet assays. Here we present a simple passive microfluidic system overcoming this limitation with unprecedented efficacy, allowing the generation of single-cell droplets for a wide range of operating conditions, with extremely high throughput (more than 22 000 single-cell loaded droplets per minute) and with an extremely low fault ratio (doublets or empty droplets), applicable to any cells and deformable particles.

Dielectrophoretic Traps for Efficient Bead and Cell Trapping and Formation of Aggregates of Controlled Size and Composition.

We present a microfluidic dielectrophoretic-actuated system designed to trap chosen single-cell and form controlled cell aggregates. A novel method is proposed to characterize the efficiency of the dielectrophoretic trapping, considering the flow speed but also the heat generated by the traps as limiting criteria in cell-safe manipulation. Two original designs with different manufacturing processes are experimentally compared.

On-Demand Nanoliter Sampling Probe for the Collection of Brain Fluid.

Continuous fluidic sampling systems allow collection of brain biomarkers . Here, we propose a new sequential and intermittent sampling paradigm using droplets, called Droplet on Demand (DoD). It is implemented in a microfabricated neural probe and alternates phases of analyte removal from the tissue and phases of equilibration of the concentration in the tissue.

Nanovolcano microelectrode arrays: toward long-term on-demand registration of transmembrane action potentials by controlled electroporation.

Volcano-shaped microelectrodes (nanovolcanoes) functionalized with nanopatterned self-assembled monolayers have recently been demonstrated to report cardiomyocyte action potentials after gaining spontaneous intracellular access. These nanovolcanoes exhibit recording characteristics similar to those of state-of-the-art micro-nanoelectrode arrays that use electroporation as an insertion mechanism. In this study, we investigated whether the use of electroporation improves the performance of nanovolcano arrays in terms of action potential amplitudes, recording durations, and yield.

Planar hydrodynamic traps and buried channels for bead and cell trapping and releasing.

We present a novel concept for the controlled trapping and releasing of beads and cells in a PDMS microfluidic channel without obstacles present around the particle or in the channel. The trapping principle relies on a two-level microfluidic configuration: a top main PDMS channel interconnected to a buried glass microchannel using round vias. As the fluidic resistances rule the way the liquid flows inside the channels, particles located in the streamlines passing inside the buried level are immobilized by the round with a smaller diameter, leaving the object motionless in the upper PDMS channel.

In-flow electrochemical detection of chemicals in droplets with pyrolysed photoresist electrodes: application as a module for quantification of microsampled dopamine.

The electrochemical quantification of analytes in droplets of PBS separated by a fluorinated phase was investigated. PDMS-fused silica chips with pyrolysed photoresist electrodes were prepared using a simple fabrication technique and used to analyze droplets in flow. Potentiostatic chronoamperometry provided current readouts consistent with mass transport and the concentration inside the droplets.

Microfluidic-assisted bioprinting of tissues and organoids at high cell concentrations.

Despite its simplicity, which makes it the most commonly used bioprinting method today, extrusion-based bioprinting suffers from its inability to reproduce the complex tissue architecture found in organs. Generally, this printing method allows for the dispensing of solutions of a predefined cell concentration through a rudimentary needle. Moreover, to avoid cell lysis in the dispensing needle, which is detrimental to the viability of the printed tissue, as well as cell loss in dead volumes of tubing, thereby increasing the cost of printing tissue, a common strategy has been to print with cell concentrations much lower in comparison to the concentrations found in living tissues.

Microfluidics: A New Layer of Control for Extrusion-Based 3D Printing.

Advances in 3D printing have enabled the use of this technology in a growing number of fields, and have started to spark the interest of biologists. Having the particularity of being cell friendly and allowing multimaterial deposition, extrusion-based 3D printing has been shown to be the method of choice for bioprinting. However as biologically relevant constructs often need to be of high resolution and high complexity, new methods are needed, to provide an improved level of control on the deposited biomaterials.

In vivo neurochemical measurements in cerebral tissues using a droplet-based monitoring system.

Direct collection of extracellular fluid (ECF) plays a central role in the monitoring of neurological disorders. Current approaches using microdialysis catheters are however drastically limited in term of temporal resolution. Here we show a functional in vivo validation of a droplet collection system included at the tip of a neural probe.

Multimaterial Nanoporous Membranes Shaped through High Aspect-Ratio Sacrificial Silicon Nanostructures.

We present an innovative fabrication method for solid-state nanoporous membranes based on the casting of sacrificial silicon nanostructures. The process allows the individual definition of geometry and placement of each nanopore through e-beam lithography and is compatible with a wide range of materials without the need to adapt the process to the materials used. We demonstrate the fabrication of membranes integrating high aspect-ratio nanopores with critical dimensions as small as 30 nm, 1.

Cell-Imprinted Substrates Modulate Differentiation, Redifferentiation, and Transdifferentiation.

Differentiation of stem cells into mature cells through the use of physical approaches is of great interest. Here, we prepared smart nanoenvironments by cell-imprinted substrates based on chondrocytes, tenocytes, and semifibroblasts as templates and demonstrated their potential for differentiation, redifferentiation, and transdifferentiation. Analysis of shape and upregulation/downregulation of specific genes of stem cells, which were seeded on these cell-imprinted substrates, confirmed that imprinted substrates have the capability to induce specific shapes and molecular characteristics of the cell types that were used as templates for cell-imprinting.

Neural probe combining microelectrodes and a droplet-based microdialysis collection system for high temporal resolution sampling.

We propose a novel neural probe which combines microfluidic channels with recording and stimulation electrodes. The developed microfabrication approach enables the concentration of every active element such as electrodes and the sampling inlet in close proximity on the same surface. As a first approach, full functional validation is presented in this work (in vivo testing will be presented in the next study).

On-chip synthesis of fine-tuned bone-seeking hybrid nanoparticles.

Aims: Here we report a one-step approach for reproducible synthesis of finely tuned targeting multifunctional hybrid nanoparticles (HNPs).

Materials & Methods: A microfluidic-assisted method was employed for controlled nanoprecipitation of bisphosphonate-conjugated poly(D,L-lactide-co-glycolide) chains, while coencapsulating superparamagnetic iron oxide nanoparticles and the anticancer drug Paclitaxel.

Results: Smaller and more compact HNPs with narrower size distribution and higher drug loading were obtained at microfluidic rapid mixing regimen compared with the conventional bulk method.

Fabrication of multilayered nanofluidic membranes through silicon templates.

We present a new fabrication method for solid-state nanoporous membranes based on sacrificial template structures made of silicon. The process consists of creating membranes by evaporating thin-films on sacrificial templates which, after their selective removal, opens the nanopores and releases the free-standing membranes. This way it is possible to define the geometry of the pore by design and to build the membrane by stacking thin-films of various materials through evaporation.