Silver nanowire arrays embedded inside polycarbonate templates are investigated as a viable thermal interface material for electronic cooling applications. The composite shows an average thermal diffusivity value of $1.89\times {10}^{-5}{\text{m}}^2{\text{s}}^{-1}$ , which resulted in an intrinsic thermal conductivity of $30.3\text{W}{\text{m}}^{-1}{\text{K}}^{-1}$ . The nanowires’ protrusion from the film surface enables it to conform to the surface roughness to make a better thermal contact. This resulted in a 61% reduction in thermal impedance when compared with blank polymer. An $\sim 30\text{nm}$ Au film on the top of the composite was found to act as a heat spreader, reducing the thermal impedance further by 35%. A contact impedance model was employed to compare the contact impedance of aligned silver nanowire-polymer composites with that of aligned carbon nanotubes, which showed that the Young’s modulus of the composite is the defining factor in the overall thermal impedance of these composites.

The development of a CMOS compatible flexible piezoelectric material is desired for numerous applications and in particular for biomedical MEMS devices. Aluminum nitride (AlN) is the most commonly used CMOS compatible piezoelectric material, which is typically deposited on Si in order to enhance the c-axis (002) crystal orientation which gives AlN its high piezoelectric properties. This paper reports on the successful deposition of AlN on polyimide (PI-2611) material. The AlN deposited has a FWHM (002) value of 5.1° and a piezoelectric d33 value of 1.12 pm V−1, and SEM images show high quality columnar grains. The highly crystalline AlN material is due to the semi-crystalline properties of the polyimide film used. Cytotoxicity testing showed the AlN/polyimide material to be non-toxic to 3T3 cells and primary neurons. Surface properties of the AlN/polyimide film were evaluated as they have a significant effect on the adhesion of cells to the film. The results show neurons adhering to the AlN surface. The results of this paper show the characterization of a new flexible-CMOS and biocompatible AlN/polyimide material for MEMS devices with improved crystallinity and piezoelectric properties.

As microelectromechanical systems (MEMS) move rapidly towards commercialization, the issue of mechanical characterization has emerged as am ajorconsideration in device design and fabrication. It is now common to includ eas et of teststructures on a MEMS wafer for extraction of thin film material properties (in particular, residual stress, stress gradient and Young's modulus), and for process and device monitoring. These structures usually consist of micromachined beams and strain gauges. Measurement techniques include tensile testing, scanning electron microscopy (SEM) imaging, atomic force microscopy (AFM) analysis, surface profiling and Raman spectroscopy. However, these tests are often destructive and may be difficult to carry out at the wafer scale. Instead of these methods, this paper uses white-light interferometry surface profiling for material characterization and device inspection. Interferometry is quick, non-destructive, non-contact, and can offer a high density lateral resolution with extremely high sensitivities to the surface in the z-direction—all essential requirements for high volume manufacturing. Ar ange of devices is employed to illustrate the capabilities of white-light interferometry as a measurement and process characterization tool. It is shown that residual stress may be determined by using electrostatic actuation to pull fixed-fixed beams towards the substrate, and interferometry to record the beam deflection profile. Finite-element simulation software is employed to model this deflection, and to estimate the material properties which minimize the difference between the measured and simulated profiles. The results agree well with blanket film measurements.