Stereolithography 3D Printing of Stimuli-Responsive Spin Crossover@Polymer Nanocomposites with Optimized Actuating Properties.

We used stereolithography to print polymer nanocomposite samples of stimuli-responsive spin crossover materials in the commercial photo-curable printing resins DS3000 and PEGDA-250. The thermomechanical analysis of the SLA-printed objects revealed not only the expected reinforcement of the polymer resins by the introduction of the stiffer SCO particles, but also a significant mechanical damping, as well as a sizeable linear strain around the spin transition temperatures. For the highest accessible loads (ca.

MEMS Biosensors and COVID-19: Missed Opportunity.

The acceleration of climatic, digital, and health challenges is testing scientific communities. Scientists must provide concrete answers in terms of technological solutions to a society which expects immediate returns on the public investment. We are living such a scenario on a global scale with the pandemic crisis of COVID-19 where expectations for virological and serological diagnosis tests have been and are still gigantic.

Complete Set of Elastic Moduli of a Spin-Crossover Solid: Spin-State Dependence and Mechanical Actuation.

Molecular spin crossover complexes are promising candidates for mechanical actuation purposes. The relationships between their crystal structure and mechanical properties remain, however, not well understood. In this study, combining high pressure synchrotron X-ray diffraction, nuclear inelastic scattering, and micromechanical measurements, we assessed the effective macroscopic bulk modulus ( B = 11.

Self-Aligned Functionalization Approach to Order Neuronal Networks at the Single-Cell Level.

Despite significant progress, our knowledge of the functioning of the central nervous system still remains scarce to date. A better understanding of its behavior, in either normal or diseased conditions, goes through an increased knowledge of basic mechanisms involved in neuronal function, including at the single-cell level. This has motivated significant efforts for the development of miniaturized sensing devices to monitor neuronal activity with high spatial and signal resolution.

A Bistable Microelectromechanical System Actuated by Spin-Crossover Molecules.

We report on a bistable MEMS device actuated by spin-crossover molecules. The device consists of a freestanding silicon microcantilever with an integrated piezoresistive detection system, which was coated with a 140 nm thick film of the [Fe(HB(tz) ) ] (tz=1,2,4-triazol-1-yl) molecular spin-crossover complex. Switching from the low-spin to the high-spin state of the ferrous ions at 338 K led to a reversible upward bending of the cantilever in agreement with the change in the lattice parameters of the complex.

Current Switching Coupled to Molecular Spin-States in Large-Area Junctions.

The fabrication of large-area vertical junctions with a molecular spin-crossover complex displaying concerted changes of spin degrees of freedom and charge-transport properties is reported. Fabricated devices allow spin-state switching in the spin-crossover layer to be triggered and probed by optical means, while detecting associated changes in electrical resistance in the junctions.

Large-scale assembly of single nanowires through capillary-assisted dielectrophoresis.

An innovative technique is proposed for the precise and scalable placement of 1D nanostructures in an affordable manner. This approach combines the dielectrophoresis phenomenon and capillary assembly to successfully align thousands of single nanowires at specific locations at the wafer. The nanowires are selectively trapped by taking advantage of the material--specific frequence dependence.

Functionalization of optical nanotip arrays with an electrochemical microcantilever for multiplexed DNA detection.

Optical nanotip arrays fabricated on etched fiber bundles were functionalized with DNA spots. Such unconventional substrates (3D and non-planar) are difficult to pattern with standard microfabrication techniques but, using an electrochemical cantilever, up to 400 spots were electrodeposited on the nanostructured optical surface in 5 min. This approach allows each spot to be addressed individually and multiplexed fluorescence detection is demonstrated.

Integrative technology-based approach of microelectromechanical systems (MEMS) for biosensing applications.

In this work we simultaneously aim at addressing the design and fabrication of microelectromechanical systems (MEMS) for biological applications bearing actuation and readout capabilities together with adapted tools dedicated to surface functionalization at the microscale. The biosensing platform is based on arrays of silicon micromembranes with piezoelectric actuation and piezoresistive read-out capabilities. The detection of the cytochrome C protein using molecularly imprinted polymers (MIPs) as functional layer is demonstrated.

Lead zirconate titanate nanoscale patterning by ultraviolet-based lithography lift-off technique for nano-electromechanical system applications.

The advantage of using lead zirconate titanate (PbZr(0.54)Ti(0.46)O(3)) ceramics as an active material in nanoelectromechanical systems (NEMS) comes from its relatively high piezoelectric coefficients.

A combination of capillary and dielectrophoresis-driven assembly methods for wafer scale integration of carbon-nanotube-based nanocarpets.

The wafer scale integration of carbon nanotubes (CNT) remains a challenge for electronic and electromechanical applications. We propose a novel CNT integration process relying on the combination of controlled capillary assembly and buried electrode dielectrophoresis (DEP). This process enables us to monitor the precise spatial localization of a high density of CNTs and their alignment in a pre-defined direction.

A dielectrophoretic continuous flow sorter using integrated microelectrodes coupled to a channel constriction.

In this article, we propose a novel dielectrophoretic continuous flow sorter using planar micro electrodes coupled to a channel constriction. This design enables a high particle sorting efficiency at low voltages while relying on a simple fabrication and integration process. We have numerically simulated the AC electrokinetic effects and the fluid behavior to predict particle trajectories.

Effect of non-ideal clamping shape on the resonance frequencies of silicon nanocantilevers.

In this paper, we investigate the effects of non-ideal clamping shapes on the dynamic behavior of silicon nanocantilevers. We fabricated silicon nanocantilevers using silicon on insulator (SOI) wafers by employing stepper ultraviolet (UV) lithography, which permits a resolution of under 100 nm. The nanocantilevers were driven by electrostatic force inside a scanning electron microscope (SEM).

Interaction of biomolecules sequentially deposited at the same location using a microcantilever-based spotter.

A microspotting tool, consisting of an array of micromachined silicon cantilevers with integrated microfluidic channels is introduced. This spotter, called Bioplume, is able to address on active surfaces and in a time-contact controlled manner picoliter of liquid solutions, leading to arrays of 5 to 20-microm diameter spots. In this paper, this device is used for the successive addressing of liquid solutions at the same location.

Direct patterning of molecularly imprinted microdot arrays for sensors and biochips.

We have used fountain pen microlithography to deposit arrays of molecularly imprinted polymer microdots on flat substrates. We visualize analyte binding to the dots by fluorescence microscopy with the aid of fluorescein as a model analyte. Elution and readsorption of the analyte to the MIP dots were possible if the porosity of the dots was improved by a sacrificial polymeric porogen.

Antibody-antigenic peptide interactions monitored by SPR and QCM-D. A model for SPR detection of IA-2 autoantibodies in human serum.

This work reports on a complementary use of surface plasmon resonance (SPR) and quartz crystal microbalance with dissipation monitoring (QCM-D) technologies to study interactions between a peptide antigen and polyclonal antibodies, in an experimental format suitable for diagnostic assays of autoimmune diseases. In the chosen model, a synthetic peptide from the juxtamembrane region of IA-2 (a type 1 diabetes associated antigen) was immobilized by an optimized chemical protocol applicable to both BIACORE and QCM-D sensors. A thorough study of the peptide immobilization was performed to optimize the signal-to-noise ratio using mixed self-assembled monolayers (SAM) on a gold surface.