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In this work, a novel hermetic packaging method using titanium and ceramic casing is proposed for long term implantable medical device. The proposed titanium-ceramic casing for implants has a better radio frequency (RF) transparency advantage as comparison to metallic materials. The proposed hermetic packaging method is used to integrate a high channels neural probe array and an active circuit module through a high density flexible cable without feedthrough integration. Hence, the profile of the integrated device achieved is as low as three millimeter and it is placed in the subdermal space. To evaluate the hermeticity of the device packaging, a helium gas leakage test was conducted and discussed. In vitro cytotoxicity test was also performed and evaluated.

This paper describes the integration of micro-electro-mechanical systems (MEMS) tri-axial force sensor using polyimide-based substrate for sensorised guide wire application. For tri-axial force sensor, piezoresistive silicon nanowires (SiNWs) are embedded into a cross cantilever design with a maneuverable stylus to allow the detection of force in all directions, and amplify the tactile forces at the tip for transverse directions. The electrical resistance changes in the four SiNWs are used to decode an arbitrary force applied onto the force sensor. Robustness of the force sensor is improved due to the novel design by incorporating a mechanical stopper at the tip of the stylus. Flip chip bonding using gold stud bumps is used to mount the force sensor on a substrate for characterization and to simplify the assembly process. The packaging process of the miniaturized sensorised guide wire was presented in this work.

In this work, we present an ultra-slim profile packaging and assembly solution of a 360-μm diameter medical guide wire fitted and integrated with silicon based fractional flow reserve (FFR) sensor. The miniaturization of the whole sensorized guide wire assembly without sacrificing its sensing functionality was made possible by the use of polyimide flexible printed circuit board (FPCB) as the substrate material for the silicon platform and by the use of lowest possible wire looping profile to create interconnection between the FFR sensor and the FPCB's bonding pads using the gold wires. In order to reinforce and protect the wire interfaces, as well as to maintain the required biocompatibility of the whole system, a thin layer of Polydimethylsiloxane (PDMS) was used for the encapsulation process. Long signal wires were then attached to the bonding pads of FPCB before finally fitted inside a miniaturized metal housing. This whole system has easily fit and integrated with the 360-μm diameter medical guide wire. In order to verify the packaging feasibility, the electrical short testing of the bonding pads and SEM observations were conducted.

In this work, we present a microfluidic platform which is capable of carrying out a series of laboratorial operations on a disposable chip. The platform employs coil arrays to transport biological samples attached on magnetic beads through different reaction zones in aqueous solutions. Micromachined thermopneumatic valves are adopted as the interfaces between sequential reactions. The self-contained system is composed of a disposable microfluidic reaction (MFR) chip and a fluidic driving/sensing (FDS) module. Various reaction zones with different functionalities are implemented on the MFR chip. Arrays of coils and micromachined heater/sensing chips are integrated into the FDS module. Also, novel indirect-heating thermo-pneumatic valves (IH-TPVs), which are monolithically integrated into the disposable MFR chip, are proposed and characterized. With an applied voltage of 3.2V, the IH-TPV effectively isolates two adjacent reaction zones, while its temperature elevation is sufficiently low for biological samples and reagents. By employing the proposed approach, we design and implement a miniaturized biochip system which carries out the processes of DNA extraction, purification and amplification from whole blood sample. The dimension of the fully-integrated system is 72 mm×54 mm×11 mm, and the system could be fully operated with a 12 V DC power supply. DNA extraction and purification from human whole blood followed by PCR amplification for the 122 bp segment is successfully performed by using the system.

The development of a flexible 32 × 32 temperature and tactile sensing array, which will serve as the artificial skin for robot applications, is presented in this work. Pressure conductive rubber is employed as the tactile sensing material, and discrete temperature sensor chips are employed as the temperature sensing cells. Small disks of pressure conductive rubber are bonded on predefined interdigital copper electrode pairs which are patterned on a flexible copper–polyimide substrate which is fabricated by micromachining techniques. This approach can effectively reduce the crosstalk between each tactile sensing element. The mechanical and electrical properties of tactile sensing elements are measured. Also, the corresponding scanning circuits are designed and implemented. The temperature and tactile sensing elements are heterogeneously integrated on the flexible substrate. By using the integrated 32 × 32 sensing arrays, temperature and tactile images induced by the heaters/stamps of different shapes have been successfully measured. The flexible sensor arrays are bendable down to a 4-mm radius without any degradation in functionality.

This paper presents the design, fabrication and measurement of a flexible 8 × 8 temperature and tactile sensing array which will be used as the artificial skin for robot applications. The temperature and tactile sensing elements are heterogeneously integrated on a flexible copper-PI film using micromachining techniques. The tactile sensing elements are formed by dispensing conductive polymer on the pre-defined interdigital copper electrodes. This novel fabrication method can effectively reduce the crosstalk between each sensing element. The strategy and the verification for reducing crosstalk currents are described. The mechanical and electrical properties of tactile sensing elements are measured. Also, discrete temperature sensor chips are employed as the temperature-sensing cells. Scanning circuits are implemented. Finally, measured temperature and tactile images have been successfully obtained by using the integrated 8 × 8 sensing arrays. The flexible sensor arrays are bendable down to a 4-mm radius without any degradation in functionality.

High peak power fiber lasers are important for a variety of applications ranging from material processing and remote sensing to laser-plasma produced extreme ultraviolet lithography (EUV) generation. These applications require high peak powers in the megawatt range, 5-MW peak power with subnanosecond pulses, the highest peak power achieved so far from a fiber laser. Use of a variety of core sizes between 65 and 200 mum has been explored and it has been shown that for core sizes as large as 80 mum, a good output beam quality of M2 ~ 1.3 can be maintained. This corresponds to the largest ever demonstrated mode area (2750 mum2) of a conventional LMA fiber with nearly diffraction-limited output. We also demonstrate average-power scaling of megawatt peak power pulses of up to ~90 W.

This paper presents a microassembly method for low-profile three-dimensional probe arrays for neural prosthesis and neuroscience applications. A silicon (Si) lead transfer structure, Si interposer, is employed to form electrical connections between two orthogonal planes—the two dimensional probes and the dummy application-specific integrated circuit (ASIC) chip. In order to hold the probe array and facilitate the alignment of probes during assembly, a Si platform is designed to have through-substrate slots for the insertion of probes and cavities for holding the Si interposers. The electrical interconnections between the probes and the dummy ASIC chip are formed by solder reflow, resulting in greatly improved throughput in the proposed assembly method. Moreover, since the backbone of the probe can be embedded inside the cavity of the Si platform, the profile of the probe array above the cortical surface can be controlled within 750 µm. This low-profile allows the probe array not to touch the skull after it is implanted on the brain. The impedance of the assembled probe is also measured and discussed. ASTAR (Agency for Sci., Tech. and Research, S’pore)

A flexible polyimide cable developed for implantable neural probe array application is presented. The flexible cable is used to connect two implantable platforms—one in direct touch with the brain containing a neural probe array and its interface IC, and the other on the skull including a wireless link IC, a coil and an antenna for power and data transfer through the transcutaneous link. The cable needs to be highly flexible to minimize post-insertion injury caused by the probe array in the presence of brain micro-motion. Polyimide is used to form a flexible substrate and an insulator layer of the cable. For the advanced neural recording system, a large amount of neural recording data has to be communicated between the two platforms through the flexible cable. High-rate data transmission performance of the fabricated flexible cable is characterized and discussed. The measured insertion loss (IL) of the flexible cable is less than 3 dB and the isolation between two adjacent interconnects is better than 17 dB up to 2 GHz. The data transmission through the flexible cable is verified to be highly reliable at 100 Mbps. For surgical manipulation and long term implantation of the neural probe microsystem, the flexible cable needs to have excellent mechanical strength and resistance to fatigue. The mechanical characteristics and fatigue strength of the flexible cable are also measured and discussed. The measured maximum tensile stress and strain of the flexible cable before failure are 251.2 ± 7.1 MPa (14.35 ± 0.3 N) and 4.16 ± 0.11 %, respectively. The Young’s modulus of the fabricated flexible cable is 8.21 GPa. From the fatigue strength testing, the measured resistance change of the flexible cable’s interconnect is less than 4.8 % after 250,000 cycles of cyclic mechanical stretch. ASTAR (Agency for Sci., Tech. and Research, S’pore)

In this work, we present the development of a polymer-based capacitive sensing array. The proposed device is capable of measuring normal and shear forces, and can be easily realized by using micromachining techniques and flexible printed circuit board (FPCB) technologies. The sensing array consists of a polydimethlysiloxane (PDMS) structure and a FPCB. Each shear sensing element comprises four capacitive sensing cells arranged in a 2 × 2 array, and each capacitive sensing cell has two sensing electrodes and a common floating electrode. The sensing electrodes as well as the metal interconnect for signal scanning are implemented on the FPCB, while the floating electrodes are patterned on the PDMS structure. This design can effectively reduce the complexity of the capacitive structures, and thus makes the device highly manufacturable. The characteristics of the devices with different dimensions were measured and discussed. A scanning circuit was also designed and implemented. The measured maximum sensitivity is 1.67%/mN. The minimum resolvable force is 26 mN measured by the scanning circuit. The capacitance distributions induced by normal and shear forces were also successfully captured by the sensing array.

This work presents the development of a capacitive tactile and shear-stress sensing array which can be easily and reliably fabricated by using MEMS techniques and flexible printed circuit board (FPCB) technologies. The sensing array consists of two micromachined PDMS structures and an FPCB with sensing electrodes. Each shear sensing element comprises four capacitive sensing element arranged in 2×2 array, and each capacitive sensing element has two sensing electrodes and a common floating electrode. The proposed design can effectively reduce the complexity of the capacitor structure without compromise in sensitivity.

This paper presents a novel design of highly twistable tactile sensing array which will be as artificial skin for robot applications. The proposed artificial skin, which employ extendable spiral electrodes, are highly flexible and durable so that it can conform to more complex surfaces without damaging the skin structure and the metal interconnects on the sensing array. Polydimethylsiloxsane (PDMS) is employed as the main structure material of the skin, and conductive polymer is used as the tactile sensing elements. The electrical characteristic of conductive polymer is measured. By using an 8×8 sensing array, the tactile images induced by PMMA stamps of different shapes are successfully captured.

The development of a flexible 8x8 temperature and tactile sensing array, which will serve as the artificial skin for robot applications, is presented in this work. Pressure conductive rubber is employed as the tactile sensing material, and discrete temperature sensor chips are employed as the temperature sensing cells. Small disks of pressure conductive rubber are bonded on pre-defined interdigital copper electrode pairs which are patterned on a flexible copper-PI substrate which is fabricated by micromachining techniques. This approach can effectively reduce the crosstalk between each tactile sensing element. The mechanical and electrical properties of tactile sensing elements are measured. Also, scanning circuits are designed and implemented. The temperature and tactile sensing elements are heterogeneously integrated on the flexible substrate. By using the integrated 8x8 sensing arrays, temperature and tactile images induced by the heaters/stamps of different shapes have been successfully measured. Radio-frequency (RF) wireless modules are also developed and integrated on the skin system.

We demonstrate a large core diameter PM Er/Yb fiber incorporating a unique raised inner-cladding which facilitates the use of conventional LMA mode selection techniques to achieve robustly single-mode operation, making it ideally suited to high power applications.

International audience; Mid-infrared supercontinuum (SC) extending to ~4.0 mum is generated with 1.3 W time-averaged power, the highest power to our knowledge, in ZBLAN (ZrF(4)-BaF(2)-LaF(3)-AlF(3)-NaF...) fluoride fiber by using cladding-pumped fiber amplifiers and modulated laser diode pulses. We demonstrate the scalability of the SC average power by varying the pump pulse repetition rate while maintaining the similar peak power. Simulation results obtained by solving the generalized nonlinear Schrödinger equation show that the long wavelength edge of the SC is primarily determined by the peak pump power in the ZBLAN fiber.

Diffraction-limited nanosecond pulse generation with MW-peak powers and multi-mJ-energies has been explored using 80-mum core Yb-doped fibers, demonstrating 1-MW peak power pulses with 85-W of average power at 100-kHz and 1.56-MW peak at 50-Hz.

Fiber-based lasers constitute next-generation in the ultrashort-pulse sources due to the significant practical advantages offered by fibers, such as high efficiency, compactness and robust all-fiber packaging of complex laser systems. In fact fiber technology has led to the first truly practical and compact mode-locked laser oscillators, which are fully compatible with rigorous reliability requirements of industrial use. However, majority of pulse-shaping and compression techniques conventionally employed for ultrashort pulse generation and control are based on using various bulk optical components (diffraction gratings in particular) and, therefore, are poorly compatible with fiber based laser systems. Here we describe our recent work on developing novel compact pulse-shaping and pulse-compression devices, which are fully compatible with fiber technology. The unifying theme of these efforts is that they use various implementations of chirped Bragg-reflection gratings. The first class of devices, pulse shapers, use combination of chirped fiber gratings and programmable MEMS arrays integrated into a single chip, to arbitrary manipulate the phase of ultrashort optical pulses on a temporal and absolute-phase magnitude scales exceeding those of conventional diffraction-grating based pulse shapers. In contrast, the second type of devices are based on volume chirped Bragg gratings to achieve pulse stretching and recompression between femtosecond to subnanosecond time scales. Use of volume gratings here offers a unique advantage of providing with compact devices which are also compatible with very high pulse energies. We have demonstrated that broad-bandwidth high-reflectivity gratings can be made in photo-thermal glass with apertures of several millimeters (and potentially much larger) thus permitting /spl sim/mJ fiber-amplified and recompressed ultrashort-pulse energies. Fiber-based chirped pulse amplification systems demonstrated using these novel pulse stretchers and compressors, combine advantages of being compact, robust, efficient, and providing with very high average power and high pulse energy ultrashort pulses.

In this work, we present the development of a capacitive tactile sensing array realized by using MEMS fabrication techniques and flexible printed circuit board (FPCB) technologies. The sensing array, which consists of two micromachined polydimethlysiloxane (PDMS) structures and a FPCB, will be used as the artificial skin for robot applications. Each capacitive sensing element comprises two sensing electrodes and a common floating electrode. The sensing electrodes and the metal interconnect for signal scanning are implemented on the FPCB, while the floating electrode is patterned on one of the PDMS structures. This special design can effectively reduce the complexity of the device structure and thus makes the device highly manufacturable. The characteristics of the devices with different dimensions are measured and discussed. The corresponding scanning circuits are also designed and implemented. The tactile images induced by the PMMA stamps of different shapes are also successfully captured by a fabricated 8 × 8 array.

Efficient generation of extreme UV (EUV) light at lambda = 13.5 nm from a bulk Sn target has been demonstrated by using a fiber laser. The conversion efficiency from the 1064 nm IR to the EUV was measured to be around 0.9% into 2pi steradians within a 2% bandwidth. To the best of our knowledge, this is the first time an all-fiber system was used to generate EUV or soft x rays.

We explored high-energy and high-peak-power pulse generation in large-core multimode fiber amplifiers, achieving what is to our knowledge the highest reported energies, up to 82 mJ for 500-ns pulses, 27 mJ for 50-ns pulses, and 2.4-MW peak power for 4-ns pulses at 1064 nm, using 200-microm-diameter and 0.062-N.A. core Yb-doped double-clad fiber amplifiers. The highly multimode nature of the fiber core was mitigated by use of a coiling-induced mode-filtering effect to yield a significant improvement in output-beam quality from M2 = 25 from an uncoiled fiber to M2 = 6.5 from a properly coiled fiber, with the corresponding reduction in number of propagating transverse modes fromor = 200 toor = 20.