Optical MEMS have been conceptualized for a large range of applications, with increasing interest devoted on raster scanning for two-dimensional (2-D) image display. With a number of advantages, including small size, light weight and fast speed compared to conventional bulky scanners, MEMS scanners have been drawing attention for a variety of applications such as heads-up display and picoprojection. The ability of MEMS scanner to display a much bigger multimedia in the forms of images, movies or presentations on an ordinary surface e.g. a wall or a table is fast attracting attention from a wide range of markets, ranging from consumer electronics to automobile.

In the case of the petrochemical industry, sensors deployed during petroleum extraction play important roles in measurement, logging and monitoring of the environment. The cumbersome procedure of extracting and analyzing samples from thousands of feet deep in the earth is expensive and time consuming. One of the possibilities of improving the efficiency is to develop a chemical sensor to detect the content of interest, especially hydrocarbon gas.To ensure a safe working environment, non-dispersive mid-IR gas-sensing system is often used in the measurement of the concentrations of hazardous or combustible gases. The essential component of a NDIR gas-sensing system includes a mid-IR radiation source, a waveguide (often used not only to collimate the light beam, but also as a gas sampling chamber), and an IR detector (often fitted with filters if the IR source is broadband). MEMS will be the core technology to realize such a handheld system consisting of an advanced microsensors-on-a-chip for multi-gas sensing.

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Since the late 90’s, the telecommunication market has attracted enormous investment on optical microelectromechanical systems (MEMS) technology as it has been recognized as an indispensable technology to fulfill a missing link that connects other existing technologies to form an all-optical communication network. Among these optical communication applications, VOA and its array are crucial components for enabling the advanced optical network. Currently, VOAs are adopted to groom power levels across the DWDM spectrum, which help minimize crosstalk and maintain the desired signal noise ratio. In the past few years, our research group has demonstrated various designs of MEMS variable optical attenuators (VOAs) driven by electrostatic, piezoelectric, electromagnetic, and electrothermal actuation.

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Photonic crystals (PCs) have found important applications ranging from lasers, waveguides, filters, modulators to sensors. In two-dimensional (2-D) PCs, resonant cavity structures can be created by introducing point and/or line defects into the 2-D PC periodic holes array in which it supports field localization in photonic bandgap. Thus PC resonators exhibit resonant wavelength peak which is a function of the surface state of the defects or the shape and dimension of defects in the PC resonant cavity structures. By designing structures of such minute sizes, many interesting phenomena have been demonstrated and examined. In particular, we have shown from our research activities that photonic crystals exhibit much potential to be an important driving force in the near future.

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Nanophotonics is the study of the behavior of light on the nanometer scale, and of the interaction of nanometer-scale objects with light. Nanophotonics can provide high bandwidth, high speed and ultra-small optoelectronic components and has the potential to revolutionize telecommunications, computation and sensing. In our group, we investigate plasmonic metamaterials and guided wave in-plane photonics as the platforms of nanophotonics at infrared and mid-infrared spectrum.

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Metamaterials have attracted intense interest for advanced applications in wide areas. Recent works on metamaterials have been extended to the terahertz (THz) frequency range, which result in new potential applications. Tunable THz metamaterials have also received significant attention because of their applications in optical communications, sensing and spectroscopy. Various methods have been proposed and demonstrated to tune the resonant frequency of a metamaterial. Among these methods, geometrically changing the metamaterial unit cells by using MEMS actuators or changing the refractive index of the metamaterial using liquid crystals are some of the research areas that we are undertaking.Our group utilize MEMS technology to explore the possibility of active control of THz metamaterial and their sensing potential.

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Frequency reference oscillator is one of the key components in current radio-frequency (RF) communication devices, with quartz crystal being widely employed as the oscillator medium. However, due to its intrinsic incompatibilities in many aspects, a much better solution is needed. Among all the possible candidates, silicon-based integrated micromechanical oscillators receive the most attention from the researchers in the related fields because of their advantage such as monolithic integration with integrated circuits. Capacitive-based and piezoelectric-based micro-resonators are the two subtypes of silicon-based integrated micromechanical oscillator. High f-Q product and low motional impedance have yet been realized at the same time for either type. To overcome this trade-off and to achieve high f-Q product with low motional impedance simultaneously are of great scientific and commercial value. Phononic crystals (PnCs), constituted by a periodical repetition of inclusions in a matrix background, is a potential candidate that we are currently researching on, which will overcome the aforementioned trade-off between Q factor and motional impedance.

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Power MEMS & energy harvesters have been developed to recharge the battery and extend the lifetime of implantable biomedical devices, wireless sensor nodes and devices operating in harsh environment. Harvesting body heat and converting these heat energy into electrical energy is one of the several promising approaches of extending the lifetime of these devices. Other approaches of energy harvesting also include collecting and converting energy from vibrations, i.e. clean and continuous energy sources. There are three kinds of energy transduction mechanisms which generate electricity from vibration, namely electrostatic, electromagnetic and piezoelectric mechanisms. Thermoelectric power generators and vibration-based energy harvesters are currently the two research areas that our group are familiar with.

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The aggressive scaling of complementary metal oxide semiconductor devices into the sub-100 nm region has resulted in increased short channel effects and gate oxide leakage, which causes a larger power dissipation and unsatisfactory device performance. In recent years, nanoelectromechanical systems (NEMS) have been intensively studied as a promising solution for future low power logic switches and nonvolatile memory applications due to their attractive characteristics such as abrupt switching and an extremely low OFF-state leakage current. However, current NEMS based switches suffer from a high activation voltage, low ON-state current, and large static friction, also known as stiction, which can lead to device failure. New approaches, in the form of material choices and structure designs, are currently undertaken by our research group to overcome the shortcomings of existing NEMS switch..

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An implantable medical device is considered to be any device that is intended to perform functions inside the body. Implantable microfabricated sensors are, for example, used to facilitate diagnosis or to provide a mean to generate closed loop therapy control. Various kinds of implantable medical devices such as intra-ocular pressure sensor, accelerometer in modern pacemakers have already been implemented in clinical trials. Such an area of research is especially important when we take into consideration of the rapid growth in the different kinds of medical applications in Singapore, particularly during the last decade. As such, we have also diverse our resources and begin making research headway on some of the important biomedical applications using MEMS/NEMS technology.

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The packaging of MEMS devices is one of the most challenging obstacles to MEMS commercialization. MEMS devices typically comprise of cavities, free-standing or even out-of-plane microstructures, while integrated circuits (ICs) do not. Due to this major difference in nature between MEMS and IC, packaging for MEMS must give space for actuator movement, allowing the sensing element to interact with the surroundings via a pathway, or provide a suitable ambient inside package to achieve higher sensitivity or better reliability. By adopting similar fabrication process flow and CMOS compatible materials such as Cu/Ni/Au metallization, such low temperature wafer bonding techniques also allows for 3D IC integration and extension of Moore's Law, hence creating a new generation of tiny but powerful devices.

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The objective of this project is to develop disposable and practical lab-on-chip (LOC) devices for a continuous flow, highly sensitive separation and detection of tumor cells in whole blood samples. Our LOC device will aim to detect even a few circulating tumour cells (CTCs) of epithelial origin inside the bloodstream in real-time, thus enabling the adoption of a suitable cure before any remarkable metastatic process occurs.

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With advances in engineering technology and nanomaterials, scientists now have access to many new and intriguing nanostructures composed of a variety of materials.  Nanotubes have become a hot topic in the area of drug delivery because of their high strength and ability to carry molecules both on the outsides and insides. Meanwhile, despite our progress in medical technology, the needle is still almost exclusively used as a vaccine delivery device.  The use of needles canlead to serious distress in children, and indoctrinates us with a negative view of doctors and health care that can last a lifetime.  Platforms to spare people the needle are seriously lacking, or they still have pain associated with their delivery. The goal of our research here is to leverage the strength of nanotubes to penetrate the skin and deliver vaccines painlessly through the first few layers of skin.

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This project aims to establish new capabilities in Singapore in developing neuroprosthetic devices. More specifically, the new capabilities will involve advancing neural stimulation and recording techniques through micro/nano technologies. The techniques proposed here are in line with the theme of the TSRP and accordingly at the interface of biology (neural or neuromuscular tissue), micro/nano neural electrodes (MEMS/NEMS), and electronics (stimulation waveform generation, low-noise recording amplifiers and signal processing). In consideration of the rapid growth in medical applications, Singapore shall expand its research base for neural interfacing so as to harvest a research ecosystem suitable for this industry sector to anchor in the region.

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