In this study, we present a comprehensive review of polymer-based microelectromechanical systems (MEMS) electromagnetic (EM) actuators and their implementation in the biomedical engineering field. The purpose of this review is to provide a comprehensive summary on the latest development of electromagnetically driven microactuators for biomedical application that is focused on the movable structure development made of polymers. The discussion does not only focus on the polymeric material part itself, but also covers the basic mechanism of the mechanical actuation, the state of the art of the membrane development and its application. In this review, a clear description about the scheme used to drive the micro-actuators, the concept of mechanical deformation of the movable magnetic membrane and its interaction with actuator system are described in detail. Some comparisons are made to scrutinize the advantages and disadvantages of electromagnetic MEMS actuator performance. The previous studies and explanations on the technology used to fabricate the polymer-based membrane component of the electromagnetically driven microactuators system are presented. The study on the materials and the synthesis method implemented during the fabrication process for the development of the actuators are also briefly described in this review. Furthermore, potential applications of polymer-based MEMS EM actuators in the biomedical field are also described. It is concluded that much progress has been made in the material development of the actuator. The technology trend has moved from the use of bulk magnetic material to using magnetic polymer composites. The future benefits of these compact flexible material employments will offer a wide range of potential implementation of polymer composites in wearable and portable biomedical device applications.

In this paper, pure molybdenum (Mo) thin film has been deposited on blank Si substrate by DC magnetron sputtering technique. The deposition condition for all samples has not been changed except for the deposition time in order to study the influence of time on the thickness and surface morphology of molybdenum thin film. The surface profiler has been used to measure the surface thickness. Atomic force microscopy technique was employed to investigate the roughness and grain structure of Mo thin film. The thickness and grain of molybdenum thin film layer has been found to increase with respect to time, while the surface roughness decreases. The average roughness, root mean square roughness, surface skewness, and surface kurtosis parameters are used to analyze the surface morphology of Mo thin film. Smooth surface has been observed. From grain analysis, a uniform grain distribution along the surface has been found. The obtained results allowed us to decide the optimal time to deposit molybdenum thin film layer of 20–100 nm thickness and subsequently patterned as electrodes (source/drain) in carbon nanotube-channel transistor.

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.

Integrated field effect transistors for microelectromechanical systems applications, modeling, and results J.The integration of p-channel metal-oxide-semiconductor transistors and tantalum bridge structures for the fabrication of resonant gate transistors (RGTs) that operate in the audible frequency range has been developed. Resonant gate transistors with channel length of 15 lm and clamped-clamped tantalum bridges of 0.5 mm to 1.6 mm in length have been fabricated. The measured first modal frequency of the bridges has been found to be higher than the expected theoretical value. From the experimental and theoretical analysis of the first three modes, the stress in the bridges has been extracted and found to be tensile with values of 3 MPa -10 MPa. Finite element simulation has validated the extracted stress and the mode shapes of the tantalum bridges. The modulation of conductance in the channel region between the source and drain by the tantalum bridge of the RGT has been demonstrated. The threshold voltage and transconductance of the fabricated p-channel RGT have been measured to be À37 V and 6.84 lS, respectively.