In this letter, we investigate the fabrication of Silicon nanostructure patterned on lightly doped (1015 cm−3) p-type silicon-on-insulator by atomic force microscope nanolithography technique. The local anodic oxidation followed by two wet etching steps, potassium hydroxide etching for silicon removal and hydrofluoric etching for oxide removal, are implemented to reach the structures. The impact of contributing parameters in oxidation such as tip materials, applying voltage on the tip, relative humidity and exposure time are studied. The effect of the etchant concentration (10% to 30% wt) of potassium hydroxide and its mixture with isopropyl alcohol (10%vol. IPA ) at different temperatures on silicon surface are expressed. For different KOH concentrations, the effect of etching with the IPA admixture and the effect of the immersing time in the etching process on the structure are investigated. The etching processes are accurately optimized by 30%wt. KOH +10%vol. IPA in appropriate time, temperature, and humidity.

The paper presents a comprehensive review of mechanical energy harvesters and microphone sensors for totally implanted hearing systems. The studies on hearing mechanisms, hearing losses and hearing solutions are first introduced to bring to light the necessity of creating and integrating the in vivo energy harvester and implantable microphone into a single chip. The in vivo energy harvester can continuously harness energy from the biomechanical motion of the internal organs. The implantable microphone executes mechanoelectrical transduction, and an array of such structures can filter sound frequency directly without an analogue-to-digital converter. The revision of the available transduction mechanisms, device configuration structures and piezoelectric material characteristics reveals the advantage of adopting the polymer-based piezoelectric transducers. A dual function of sensing the sound signal and simultaneously harvesting vibration energy to power up its system can be attained from a single transducer. Advanced process technology incorporates polymers into piezoelectric materials, initiating the invention of a self-powered and flexible transducer that is compatible with the human body, magnetic resonance imaging system (MRI) and the standard complementary metal-oxide-semiconductor (CMOS) processes. The polymer-based piezoelectric is a promising material that satisfies many of the requirements for obtaining high performance implantable microphones and in vivo piezoelectric energy harvesters.

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This paper describes the design and fabrication of planar micro-coil on printed-circuit board (PCB)for magnetic MEMS actuator. A simple and cost effective technique for the fabrication of planar micro-coil is presented. The design and analysis process have been carried out by using COMSOL Multiphysics 4.2. Three different coil dimensions such as width/space= 150µm/100µm; 100µm/100µm and 50µm/100µm, have been analyzed in order to find the optimum coil geometry. The results showed that the coil with dimension of width/space of 50µm/100µm produced the highest magnetic flux density of max 0.0068 T. The optimized design of the planar micro-coil can be used as a reference for the future fabrication of magnetic MEMS actuator.

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The characterization of the KOH aqueous solution was done in order to study the effects of temperature and KOH concentration on the silicon etching rate for membrane formation. The study was done for temperatures ranging from 65OC to 80°C and KOH concentration ranging from 15% to 55%. Experiments showed that the temperature of 80°C and KOH concentration of 35% will yield the optimum etching rate with the minimum surface roughness. A silicon membrane of thickness 48pm was produced with KOH concentration of 35% at the temperature of 75°C for 7 hours and 45 minutes and the etching profile analyzed.