A fully integrated micromachined magnetic particle separator

A prototype micromachined magnetic particle separator that can separate magnetic particles from suspended liquid solutions has been realized on a silicon wafer. The requisite magnetic field gradients are generated by integrated inductive components in place of permanent magnets, which yields several advantages in design flexibility, compactness, electrical and optical monitoring, and integration feasibility (thus enabling mass production). Preliminary experiments have been performed on aqueous suspensions of magnetic beads. At 500 mA of dc current, approximately 0.03 Tesla of magnetic flux density is achieved at the gap between the quadrupoles, and the magnetic particles rapidly move toward the quadrupoles, separate from the buffer solution, and clump on the poles. The magnetic particles clumped on the poles are also easily released when the dc current is removed, achieving the primary purpose of a separator. The device shows that micromachined magnetic components have a high potential in biological or biomedical applications, especially in separating small amounts of cells or DNA that are marked with magnetic beads, especially when close monitoring and control of the process is important     

A monolithically integrated surface micromachined touch mode capacitive pressure sensor

A monolithically integrated surface micromachined touch mode capacitive pressure sensor and its interface circuits are presented. The device includes the capacitance to voltage, and capacitance to frequency converters on the same chip. The sensor is fabricated using a surface micromachining technology, which is processed simultaneously with a conventional 2.0-μm double-poly, double-metal n-well CMOS process. The performance of the integrated sensor meets the design specifications of good linearity and good stability. Evaluation results on the completed ‘sensor and circuit' chip are presented.     

Single core fully integrated CMOS micro-fluxgate magnetometer

A new fully integrated 2D micro-fluxgate magnetometer is presented. This magnetometer is integrated in a standard CMOS process and uses a ferromagnetic core integrated on the chip by a photolithographic post-process compatible with the integrated circuit technology. The cross-shaped ferromagnetic core is placed diagonally above four excitation coils, two for each measurement axis. A novel electronic signal extraction technique is presented. The integrated 2D magnetometer exhibits a sensitivity of 160 V/T and a linear range of ±50 μT. The magnetic equivalent noise spectral density is 70 nT/√Hz at 1 Hz, and the total power consumption is as low as 17 mW for the 5 V power supply.     

Low power integrated fluxgate sensor with a spiral magnetic core

Facing the new integrated applications, coordination between three parameters of the micro fluxgate sensor, namely, sensitivity, power consumption and operation range, is the key to make the applications come true. This paper reports a new low power micro integrated fluxgate sensor with low cost solution. A spiral electroplating permalloy magnetic core is introduced to reduce excitation current. Due to the design of little coils resistance and thick magnetic core, the fluxgate sensor exhibits a power consumption of 7.35 mW, a sensitivity of 117 V/T and a linear range of −200 to 200 μT. Compared with the constant-width magnetic core and the multi rectangular ring magnetic cores, experiment results show that the spiral magnetic core benefits both smaller excitation current and higher sensitivity. The newly developed fluxgate sensor maintains high sensitivity and wide linear range with low power consumption.     

A miniaturized bulk micromachined triaxial accelerometer fabricated using deep reactive etching through a multilevel thickness membrane

We present the design, fabrication and characterization of an application specific triaxial accelerometer for post-surgery heart monitoring. The accelerometer chip is designed as a 2?×?4?×?1.2?mm³ chip with nominal acceleration range of?±4?g and frequencies below 50?Hz. It has been fabricated using a multiproject wafer service with an additional deep reactive ion etching process to obtain controlled etch-through of membranes of 3, 23 and 400?μm thicknesses simultaneously. The novelty of the work presented here is the bulk micromachining technique using both deep reactive dry etching and alkali-based anisotropic wet etching of single crystal (100) silicon wafers used to obtain a space efficient design. Proof of concept is demonstrated with preliminary testing, with an acceleration sensitivity of?~0.04 mv/V/g for out of plane (z axis) acceleration.     

一种应用于无线传感器网络的全集成接收信号强度指示器

设计了一种应用于无线传感器网络(WSNs),可以在1.2V电压工作的,全集成接收信号强度指示器(RSSI).介绍了对数放大器的基本原理,改进了直流偏移消除电路结构,利用隔级反馈使限幅放大器部分更加易于全集成.改进了全波整流电路,使其能工作在低电压,功耗更低,同时大大提高了工艺稳定性和温度稳定性.采用0.18 μm CMOS工艺,仿真结果显示:在1.2V电源电压时,RSSI的直流电流小于0.6mA,2 MHz输入信号频率,输入动态范围为-85 ～-10 dBm时,RSSI的线性误差小于±0.5 dB.     

Capacitive microphone with a surface micromachined backplate usingelectroplating technology

A technology for surface micromachining of free-standing metal microstructures using metal electrodeposition on a sacrificial photoresist layer has been applied to a condenser microphone. Electroplating technology has been used to implement a suspended and perforated 15-μm-thick microstructure in copper, which serves as backplate electrode in the condenser microphone. The 1.8×1.8 mm ² large microphone diaphragm is in monocrystalline silicon and is fabricated with anisotropic etching of the substrate wafer. The realized prototypes have a measured sensitivity of 1.4 mV/Pa using a bias voltage of 28 V. The bandwidth is limited by an anti-resonance at 14 kHz which is due to the semi-rigid backplate. The resonance behavior of the backplate structure has been analyzed with finite element modeling with results in good agreement with measured data     

A compact electromagnetic micro-actuator using the meander springs partially exposed to magnetic field

We present the design, fabrication, and testing of a compact electromagnetic micro-actuator using meander springs that are partially exposed to the magnetic field. The previous electromagnetic micro-actuators using cantilever springs require large electromagnetic force for large displacement actuation and therefore require high-current input and a large magnet. The previous electromagnetic actuators using low-stiffness meander springs are limited in large displacement actuation because actuation forces cancelled each other due to changes in the current path under the magnetic field. In this paper, we compare two prototypes: a conventional prototype F with the meander springs exposed fully to the magnetic field and the present prototype P with the meander springs partially exposed to the magnetic field. In the experimental study, the amplitude of prototype P is measured as 30.49 ± 0.36 µm at the 40 mA square input current, while the amplitude of prototype F is measured as 26.02 ± 0.65 µm. The amplitude of prototype P is 17.2 % larger than that of prototype F, verifying the effect of partial exposure of the meander springs to the magnetic field. Therefore, we experimentally demonstrate the large-displacement actuation performance of the present actuator using the partial exposure of the meander springs to the magnetic field.     

Die separation and packaging of a surface micromachined piezoresistive pressure sensor

The processing steps required to obtain a useful single medical sensor assembly are discussed, starting from an entire silicon wafer with thousands of surface micromachined sensors. Experiences concerning dicing and packaging of a piezoresistive pressure sensor are described, together with proposals for solutions. Problems with fracture of essential sensor structures are solved by use of a wafer protection tape. Existing solutions for flip–chip bonding and design of substrate for electrical interconnection are pushed to their limits due to the very small size of the novel sensor. As many of the processes can be simplified by an improved MEMS design, critical points related to the design are addressed.     

A differential transformer-based force sensor utilizing a magnetic fluid core

Microsystem Technologies - A force sensor utilizing a transformer concept with a ferrofluid core was developed. A ferrofluid reservoir was machined out of Teflon and the open top of the reservoir...     

A design methodology for fully integrated MEMS and NEMS Pierce oscillators

This work proposes a generic methodology to evaluate the feasibility of designing a Pierce oscillator based on a micro or nanoresonator fabricated with any given CMOS technology and with the constraint of using only one single active transistor. Both the design and the transimpedance gain of the electronics are analytically determined for resonators with capacitive or resistive detection. This approach is applied and validated in the case of (a) an electrostatically actuated clamped-clamped beam resonator using a capacitive transduction, and (b) a piezoresistive crossbeam, both based on a standard 0.13 μm CMOS technology.     

A wireless powered fully integrated SU-8-based implantable LC transponder

In this work, we report a SU-8-based fully integrated miniaturized inductively powered LC transponder for generic implantable wireless sensor applications. It consists of a 1 mm diameter octagonal spiral inductor and a micro fabricated MIM (metal insulator metal) capacitor. Polyvinylidene Fluoride–Trifluoroethylene (PVDF–TrFE) copolymer is applied as a dielectric material for the capacitor fabrication due to its high dielectric constant. The 1 mm diameter, 154 nH spiral inductor is built on top of the capacitor. The capacitor and the inductor are in parallel connection through SU-8 via holes. SU-8 is used as a packaging material due to its biocompatibility, and also it serves as an insulator between the capacitor and the spiral inductor. The operating frequencies of the LC tanks are decided by the sizes of the capacitors (45 × 45, 55 × 55, 95 × 95 and 100 × 100 μm), and measured operating frequency range is from 385 to 485 MHz. The fabricated LC tanks are held to the power transmitting coil coaxially at distances of 2, 5, 7 and 10 mm, and rectified induced voltage at the LC tank is 8.5 V with 29 dBm input power at a 5 mm distance.     

Design and fabrication of a micromachined planar patch-clamp substrate with integrated microfluidics for single-cell measurements

We have designed, fabricated, tested, and integrated microfabricated planar patch-clamp substrates and poly(dimethylsiloxane) (PDMS) microfluidic components. Substrates with cell-patch-site aperture diameters ranging from 300nm to 12 /spl mu/m were produced using standard MEMS-fabrication techniques. The resistance of the cell-patch sites and substrate capacitance were measured using impedance spectroscopy. The resistance of the microfabricated apertures ranged from 200 k/spl Omega/ to 47 M/spl Omega/ for apertures ranging from 12 /spl mu/m to 750 nm, respectively. The substrate capacitance was 17.2 pF per mm/sup 2/ of fluid contact area for substrates with a 2-/spl mu/m-thick layer of silicon dioxide. In addition, the ability of the planar patch-clamp substrates to form high-resistance seals in excess of 1 G/spl Omega/ has been confirmed using Chinese hamster ovary cells (CHO-K1). Testing shows that the microfluidic components are appropriate for driving human embryonic kidney cells (HEK 293) to patch apertures, for trapping cells on patch apertures, and for exchanging the extracellular fluid environment.     

A design method and its CAD prototype system for surface micromachined MEMS devices

Microsystem Technologies - Now the MEMS design method of “bottom–up” (mask-to-shape-to-function) has been adopted widely. However, it is complicated, time-consuming and not...     

Electroplating a magnetic core for micro fluxgate sensor

A square-ring shaped micro fluxgate sensor, which was designed for measuring two axes weak magnetic field at the same time, was fabricated using MEMS technologies. To get better magnetic properties, Ni/Fe permalloy was selected to be the materials of magnetic core which was fabricated by DC-electroplating method with several micron thickness. Saccharine was added into the electrolyte to reduce the internal stress, and its influence on magnetic properties was studied. The results show that magnetic properties are related to the crystalline phase transition in the deposition which varied with saccharine content. With 3 g/L saccharine in the electrolyte, a film with low coercive force and high saturation magnetization relatively was obtained and some characters of the sensor were also discussed in the paper.     

A 65 mW fully integrated UHF-band CMMB tuner in 65 nm CMOS process

A low power fully integrated digital TV tuner chip for China Mobile Multimedia Broadcasting(CMMB) application is presented.Based on direction conversion architecture,analog 8th-order filter/gain stages utilizing high power efficient operation-amplifiers and a ΣΔ fractional-N phase locked loop(PLL) with one voltage controlled oscillator(VCO) covering 4.8—7.2 GHz is proposed for low power and small chip area.The tuner is implemented in 65 nm CMOS process with low noise amplifier(LNA) matching network and phase locked loop(PLL) filter integrated on chip,occupying a chip area of 4.83 mm2.The measured noise figure(NF) is less than 3.2 dB over CMMB UHF band(470—798 MHz).A total power consumption of 65 mW(54 mA from 1.2 V supply) is achieved.     

A remotely powered fully integrated low power class-E power amplifier for implantable sensor systems

This paper presents a fully integrated low power class-E power amplifier and its integration to remotely powered sensor system. The on-chip 1.2 GHz power amplifier is implemented in 0.18 µm CMOS process with 0.2 V supply. The implantable system is powered by using an inductively coupled remote powering link at 13.56 MHz. A passive full-wave rectifier converts the induced AC voltage on the implant coil into a DC voltage. A clean and stable 1.8 V supply voltage for the sensor and communication blocks is generated by a voltage regulator. On–off keying modulated low-power transmitter at 1.2 GHz is used for the transmission of the data collected from the sensors. The transmitter is composed of a LC tank oscillator and a fully on-chip class-E power amplifier. Compared to the conventional class-E power amplifiers, an additional network which reduces the on-chip area is used at the output of the power amplifier. The measurement results verify the functionality of the remotely powered implantable sensor system and the power amplifier. The integrated power amplifier provides ?10 dBm output power for 50 Ω load with a drain efficiency of 31.5 %. The uplink data communication with a data rate of 600 kbps is established by using a commercial 50 Ω chip antenna at 1 m communication distance.     

A low power micro fluxgate sensor with improved magnetic core

The influence of an improved magnetic core on the micro fluxgate sensor about sensitivity and power consumption is investigated and discussed in this paper. We have fabricated the micro solenoid fluxgate sensors based on the MEMS technologies, with the electroplating permalloy cores, which are easy to process and used in common; and the amorphous soft magnetic ribbon cores, which have better soft magnetic performances but be hard to be integrated, respectively. Four magnetic core structures are designed, including rectangular structure, unequal width rectangular structure, multi rectangular ring structure and spiral structure. Spiral structure can improve the performances of the fluxgate sensor significantly, both sensitivity and power consumption. The micro fluxgate sensors with the amorphous soft magnetic ribbon cores are promoted in all aspects than those with the electroplating permalloy cores, including ultra low power consumption of 2.4 mW with unequal width rectangular structure, and high sensitivity of 118 V/T with rectangular structure in wide linear range of 0–800 μT.