The process complexity of a micromachined device is directly related to the number of layers needed. Miniature planar fluxgate magnetic sensors commonly use two or more layers of coils. The manufacture process of micromachined planar fluxgate sensors with all the coils contained in a single metal layer is here presented. NiFe cores were electroplated through photoresist molds. Characterization in respect to noise levels and sensitivity are detailed discussed. Noise levels down to 40 nT rms in the 0.1 -10 Hz range were achieved. Two different layouts are presented and one of them has the potential to further noise level reduction just by increasing either the excitation amplitude or the coils pitch.

This paper describes a simple method to fabricate silicon microtips with integrated self-aligned polarization electrodes for development of MEMS and electron field emission devices. The method is based on the wet bulk micromachining of the silicon substrate in KOH solutions and utilizes low stress PECVD SiOxNy films obtained at low temperatures (320°C) as structural material for both mechanical support and electrical insulation of the electrodes. For the electrodes sputtered Cr films were utilized. The microtip formation process was studied by optical and electronic microscopy to analyze tip geometry and the characteristic etch rate of the different stages during the tips formation. The fabricated devices were matrixes with different numbers of microtips, each with a typical height of 52 μm and with diameter at the apex below 1 μm. In the best case, the distance between the apex of the tips and the metallic electrode was lower than 5 μm. The results also show that the low stress SiOxNy film is essential to attain the necessary flatness required by the process.

This paper presents the development of a thermal flow sensor integrated to a microchannel aiming its application in biological and chemical systems. The sensor is composed by a thin-film nickel heater deposited on a glass slice by electroplating and a microchannel fabricated on PDMS by soft lithography. Computer simulations were utilized to determine the electrical behavior of the sensor and the temperature distribution. The results show the sensor presents adequate sensibility with low interference in the fluid flow and its fabrication can be easily introduced in the standard fabrication process of PDMS-based microsystems.

This paper reports the fabrication of complete microfluidic system utilizing Corning 7059 glass substrates. The method utilized to obtain the microfluidic system, combines techniques such as photolithography and wet etching to produce the microchannels and room temperature direct bonding as an encapsulating process. Mechanical drilling with dental diamond bur was utilized to produce access holes for external interconnections. To guarantee the necessary alignment during the encapsulation process, a computer controlled system was developed to move and position the dental bur utilized to make the access holes. The structures were characterized by optical and electronic microscopy and video camera was utilized for liquid flow characterization. The obtained results show that the proposed fabrication method is fast, reproducible and allow the fabrication of glass microchannels with depths up to 150 mm, without evidence of liquid leakage. For the all the studied conditions, we observed a liquid flow with laminar behavior.

A microfluidic system, fully operational for further studies of foraging abilities of marine microorganisms, is presented. The microchannels are fabricated in PDMS (polydimethylsiloxane) by a simple, fast and low-cost soft lithography method, utilizing a SU-8 photoresist master. The devices exhibit a quite satisfactory performance, since we obtain the expected laminar flow regime. No leakage was observed in the channel itself and the appropriate flow control was attained. This allows to reproduce, in controlled and realistic conditions, resource patches existing in the ocean at submillimetric scales.