This paper reports the maskless fabrication of a microfluidic device with interdigitated electrodes (IDE) based on the technology of MicroElectroMechanical Systems on Printed Circuit Board (PCB-MEMS) and laser ablation. The device has flame retardant (FR)-4 resin as substrate, cooper (Cu) as active material and SU-8 polymer as structural material. By adjusting the laser parameters, Cu IDEs and SU-8 microchannels were successfully patterned onto the FR-4 substrate. The respective width, gap and overlap of the IDEs were 50 μm, 25 μm and 500 μm. The respective width, depth and length of the microchannels were 210 μm, 24.6 μm and 6.3 mm. The resolution and repeatability achieved in this approach, along with the low cost of the involved materials and techniques, enable an affordable micromachining platform with rapid fabrication-test cycle to develop active multiphysic microdevices with several applications in the fields of biosensing, cell culture, drug delivery, transport and sorting of molecules, among others.
Residual stress can affect the performance of thin-film micromachined structures and lead to curling in cantilevers as well as distortion in the frequency of resonant devices. As the origin of residual stress is dependent on the fabrication processes, a nondestructive method for characterization of residual stress independent of processes conditions is desirable for supporting the design of microcantilever-based microsystems. In this paper we present a nondestructive characterization of the residual stress within composite microcantilever beams providing valuable insights toward
predicting their deflection profile after mechanical releasing from the substrate. The approach relies on the assumption of a linear gradient stress and a quadratic deflection profile across a composite microcantilever.
Surface Plasmon Resonance (SPR) is a wave phenomenon occurring at an interface between a dielectric and a metal. SPR has applications in label-free biodetection systems, where advances in microfabrication techniques are fostering the development of SPR-based labs-on-a-chip. This work presents a numerical analysis for the excitation of SPR using Kretschmann's configuration. With a SiO2 prism, an Au metal layer, and water as the dielectric, the system is made to be compatible with a post-CMOS microfabrication process. The results obtained from both theory and software simulation show that for a light source at 633 nm, a 50 nm thick Au film is optimal, with the reflectivity falling to a minimum of ~2% at an angle of ~68.5°, due to maximum electromagnetic SPR coupling. Simulations with a Ti adhesion layer were
also performed, showing a negative effect by increasing to ~17% the minimum reflectivity when SPR is achieved, thus reducing the dynamic range of the signal captured by the system's photodetector. SPR biosensors work by monitoring changes on the refractive index close to the SPR interface, these changes were simulated showing that a change of ~10-4 RIU on the dielectric medium produces a ~0.01°change in the SPR angle. These results will facilitate the physical implementation of label-free biosensing platforms with a CMOS image sensor (CIS) photodetection stage.
This work reports the experimental validation of a novel one-dimensional microscanner. The composite cantilever
device implements thermoelastic resonant actuation using temperature gradients induced across two frequency-selective
directions as a strategy to increase operating speed and decrease damping. The device was fabricated using 0.35-μm
CMOS technology and aspect ratio dependent etch modulation. Resonance peaks were measured around 6.4 and 44.7
kHz at atmospheric-pressure conditions; the power sensitivities (2.8 and 1.6 °/W) of the device may compromise its
performance for low-power, large-angle applications. Ultimately, the device is suitable for applications requiring a
variation from low- to high-stability conditions with increasing operating speed.
Micro-Electro-Mechanical Systems are nowadays frequently used in many fields of industry. The number of their applications increase and their functions became more complex and demanding. Therefore precise knowledge about their static (shape, deformations, stresses) and dynamic (resonance frequencies, amplitude and phase of vibration) properties is necessary. Two beam laser interferometry is one of the most popular testing methods of micromechanical elements as a non-contact, high-accurate method allowing full-field measurement. First part of the paper present microbeam actuators designed for MEMS/MOEMS applications. The proposed structures are the straight silicon microbeams formed by KOH etching of Si wafer. Aluminium nitride (AlN) thin films are promising materials for many acoustic and optic applications in MEMS field. In the proposed architecture the actuation layer is sandwiched between two metal electrodes on the top of beam. In the second part we describe the methodology of the actuator characterization. These methods applied are: stroboscopic interferometry and active interferometry (LCOS SLM is used as a reference surface in Twyman-Green interferometer). Moreover some results of FEM analysis of the sample are shown and compared with experimental results. Dynamic measurements validate the design and simulations, and provide information for optimization of the actuator manufacturing process.