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.     

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.     

微型磁通门传感器的低功耗结构设计

微型磁通门的功耗是影响其整体性能的关键因素.要降低功耗必须保证器件的薄膜铁芯能够在较小的激励电流下进入饱和状态,为此,可以通过降低铁芯的饱和磁场强度Hs来实现这一目标.设计了一种具有多孔结构薄膜铁芯的微型磁通门,经过有限元仿真分析发现,多孔结构能够降低磁通门铁芯的饱和磁场强度Hs,从而获得较小的饱和激励电流,在保证微型磁通门灵敏度的同时,有效降低器件功耗.     

Improved micro fluxgate sensor with double-layer Fe-based amorphous core

A rapid manufacturing process for the micro solenoid fluxgate sensor integrating multilayer amorphous ribbon core has been established, which combines the micro assembling method and the MEMS technologies. We select Fe-based amorphous soft magnetic ribbons for core materials and have fabricated the micro fluxgate sensors by MEMS technologies, with single-layer core and double-layer core respectively. The micro fluxgate sensors with double-layer core show the advantageous to that with single-layer core and exhibit sensitivity of 1089.2 V/T at excitation current of 120 mA rms, wide linear range of ?900 to 900 μT and power consumption of 24.48 mW. The noise power density of the single core fluxgate sensor is 2.48nT/Hz^1/2@1 Hz.     

Two-axis micro fluxgate sensor on single chip

We present a two-axis micro fluxgate sensor on single chip for electronic compassing function. To measure X- and Y-axis magnetic fields, functional two fluxgate sensors were perpendicularly aligned and connected each other. The fluxgate sensor was composed of square-ring shaped magnetic core and solenoid excitation and pick-up coils. The solenoid coils and magnetic core were separated by benzocyclobutane which had high insulation and good planarization characters. Copper coil patterns of 10 μm width and 6 μm thickness were electroplated on Ti (300 Å)/Cu (1,500 Å) seed layers. 3 μm thick Ni_0.8Fe_0.2 (permalloy) film for the magnetic core was also electroplated under 2,000 gauss. Excellent linear response over the range of ?100 μT to +100 μT was obtained with the sensitivity of ～280 V/T. Actual chip size was 3.1×3.1 mm². The sine and cosine signals of two-axis fluxgate sensor had a good function of azimuth compass.     

Improved performance of the micro planar double-axis fluxgate sensors with different magnetic core materials and structures

As a classic weak magnetic field sensor, the fluxgate sensors have great potential application in many fields. This paper presents four kinds of the micro planar double-axis fluxgate sensors based on the MEMS technologies, which have different core materials and core structures. The core materials include electroplated permalloy, Co-based amorphous ribbon and Fe-based amorphous ribbon, and the core structures include single-layer open magnetic loop structure and double-layer closed magnetic loop structure. The sensor with closed double-layer Fe-based ribbon core exhibits a best sensitivity of 238 V/T due to reducing the magnetic flux leakage. The results show that the magnetic core with closed magnetic loop, high permeability and high saturation induction density will help increase the sensitivity of the micro double-axis fluxgate sensor.     

微型磁通门铁芯结构的拓扑分析与优化

多孔铁芯有利于满足微型磁通门传感器降低功耗的要求,但不同的拓扑结构所取得的效果不同,对多孔铁芯结构进行了拓扑分析与针对性优化,并采用微机电系统(MEMS)工艺制备了不同铁芯结构的微型磁通门进行性能测试与对比验证.实验结果证明:优化后的铁芯结构能更好地降低微型磁通门传感器功耗,提高器件整体性能.     

新型环形同点单铁芯双分量磁通门传感器

双分量磁通门传感器在金属磁记忆检测中得到广泛使用,且使用的双分量磁通门传感器为双铁芯式跑道型设计的磁通门传感器。由于传感器中的双铁芯磁参数不一致、铁芯不闭合的原因,产生变压器效应,形成了测量噪声。双分量磁通门通常由两个磁通门传感器平行放置而成。因此,由于传感器铁芯参数,线圈参数不可能完全一致所造成的传感器之间的一致性差,而且双分量或多分量磁通门传感器存在着几何中心不重合的问题。本文研究设计了新型双分量磁通门传感器,采用环形铁芯设计,直接应用单铁芯调理双方向的磁通门信号,改善了双分量传感器的一致性差、几何中心不同点的问题,有效的抑制了变压器噪声,提高了磁通门传感器的测量中的测量准确度,减少了测量误差。     

一种基于MDAC优化的低功耗流水线A/D转换器

设计了一种低功耗16位100 MS/s的流水线A/D转换器。通过采用级间电容缩减技术,并优化增益数模转换器(MDAC)的结构,降低采样电容的面积。流水线前两级采用高性能低功耗运算跨导放大器(OTA),通过动态偏置技术进一步降低功耗。芯片采用0.18μm混合信号CMOS工艺,1.8 V单电源供电。经测试,流水线A/D转换器在5 MHz的输入频率下,信噪失真比(SNDR)为74.2 dB,无杂散动态范围(SFDR)为91.9 dB,整体功耗为210 mW。     

一种平面四轴向磁通门传感器的设计

设计了一种新型的四轴向磁通门传感器,可测量铁磁性目标经过时产生的磁异信号在四个轴向上的变化情况,通过各轴间的相关性即可判断出目标的运动方向。结构中将四个三端式磁通门探头单元相间45°摆放,使得传感器的任一侧都有四个磁场强度分量的输入,结合分时激励的方法,与传统磁通门传感器相比,其具有电路简单,灵敏度高、稳定性好、功耗小等优点。经实验表明,该传感器方向识别正确率可达85%以上,能够较好的应用于安防及侦测领域中对目标运动及其方向的监测。     

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...     

地磁相对记录用低噪声磁通门磁力仪

针对地磁相对记录要求观测仪器具有高分辨力、低噪声和长期稳定性的特点,抑制外界温度对传感器输出的影响,获得较低的温度系数,研制的磁通门传感器采用高导磁率坡莫合金作为磁芯材料,激励线圈直接缠绕在高塑性、较高持久蠕变强度的环形合金骨架上,感应线圈和补偿线圈缠绕在低温度系数的玻璃钢骨架上.采用交变模拟信号处理电路、深度负反馈网...     

MEMS micro fluxgate sensors with mutual vertical excitation coils and detection coils

As a classic Earth magnetic field sensor, fluxgate magnetic sensors have great potential applications in many fields. This paper presents a new 3D micro-solenoid fluxgate magnetic sensor based on the MEMS technique. The excitation coils were placed vertically to the detection coils on the chip plane, around a rectangular shaped magnetic core. Polyimide was used to insulate coils and magnetic core. Width of copper conductor lines is 50 μm, and line space is 50 μm. The design of such fluxgate magnetic sensor followed second harmonic signal selecting method. Phase-lock amplifier was used to get second harmonic signal output by detection coils. The linear range of 0–80 μT with sensitivity of 6.7 V/T was achieved from the fabricated sensor with excitation current of 430 mA and the operational frequency of 40 KHz. As the excitation current was 470 mA, linear range of 0–50 μT with sensitivity of 21.7 V/T was achieved.     

一种低功耗的无线传感器网络MAC协议

在无线传感器网络中,为了避免不必要的能耗而达到延长网络寿命的目的,提出一种低功耗的无线传感器网络MAC协议。此协议在低功率侦听(LPL)基础上进行修改,通过前一次轮询的结果来推测这一次的流量状况,根据流量状况自适应调整侦听睡眠周期结构中相应的占空比,从而降低能耗。通过编程仿真并结合实验,对此模型进行验证,证明了此算法能降低能耗。     

一种应用在人体传感器网络的低功耗VCO

人体通信作为人体传感器网络的一种新兴的通信方式,有着突出的优势与巨大的潜力.介绍了应用在人体通信无线收发器的压控振荡器(VCO)的设计与测试.该模块采用了四级双差分结构,采用SMIC 0.18 μm 1P6M工艺,核心面积仅为0.02 mm2.测试结果显示:在1.8V供电电压下,VCO调谐范围为30～130 MHz,在80 MHz输出频率下,1 MHz频偏处相位噪声为-98 dBc/Hz,最大功耗仅为1.27 mW,较好地满足了采用人体通信作为通信方式的人体传感器网络的要求.     

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 pulse switching paradigm for ultra low power cellular sensor networks

This paper presents a novel energy-efficient and fault-tolerant pulse switching protocol for ultra-light-weight wireless cellular network applications. The key idea of pulse switching is to abstract a single pulse, as opposed to multi-bit packets, as the information exchange mechanism. In this paper it is shown to be sufficient for event and target tracking applications with binary sensing in terms of cellular localization. Event monitoring and target tracking with conventional packet transport can be prohibitively energy-inefficient due to the communication, processing, and buffering overheads of the large number of bits within a packet’s data, header, and preambles. Additionally, both of them can be unreliable without protection from errors and faults occurrence. The paper presents a joint MAC and Routing architecture for pulse switching with a novel cellular event localization in the presence of errors and faults. Through analytical modeling and simulation experiments, it is shown that cellular pulse switching can be an effective means for event based networking, which can potentially replace the packet transport when the information is binary in nature.     

新型传感器部件——可移动铁芯的微型线圈

介绍一种新型的传感器部件 ,具有可移动铁芯的微型线圈。这种线圈是通过移动穿过线圈的铁芯 ,来改变线圈的磁感应强度。它具有灵敏度高、线性度好、体积小、使用方便等特点。适合应用于位移传感器和角度传感器     

A high accuracy fluxgate DC current sensor applicable to two-wire electric appliances

Microsystem Technologies - This paper presents a novel high-precision low noise self-oscillating fluxgate DC current sensor that can be used for two-wire measurement. This new sensor mainly...     

低功耗In_2O_3基LPG气敏元件

采用In2O3超细粉体,掺杂Au和金属氧化物(SiO2,Fe2O3等),按照直热式气敏元件工艺制成珠状气敏元件,通过Al2O3 Pd的表面催化层处理,研制出功耗低于100mW(在空气中)的液化石油气(LPG)气敏元件。并分析了元件的气敏机理。