一种用于生物检测的半导体电场效应传感器

设计了一种简化的铝栅MOS半导体器件制作工艺流程,用6张掩模版成功制作出了基于表面电场效应原理的生物检测硅芯片传感器,采用SiO2-Si3N4复合栅介质层及耗尽型器件结构,以增强器件的识别与检测灵敏度。该传感器与常规铝栅MOS晶体管相比,去除了介质层表面的栅极导电层,代之以自组装技术制作生物薄膜并辅以栅参考电极作为控制栅极。用所制作的硅芯片传感器检测了相关生物蛋白质的电流响应,给出了该电流响应与器件沟道长度和沟道电阻及生物蛋白浓度等参数的关系,得到了较为满意的检测数据,达到了预期的基于表面电场效应的硅传感器制作和生物检测的目的。     

基于分子印迹聚合膜的胆固醇丝网印刷生物传感芯片

该文基于自组装技术在丝网印刷金电极表面制备分子印迹膜,研制胆固醇电化学仿生生物传感芯片。利用扫描电镜(SEM)对平面裸金电极、厚膜裸金电极及其修饰电极进行了形貌的分析比较,采用循环伏安分析法对电极修饰过程的电化学特性进行表征,采用计时电流法对胆固醇生物传感芯片的浓度响应特性进行检测。结果表明, 基于丝网印刷工艺的厚膜电极不仅能满足自组装分子印迹仿生膜的修饰,而且电极表面具有明显的纳米放大效应。传感器对0~700 nM不同浓度胆固醇进行检测,线性范围50 nM~700 nM,灵敏度达到-4.94 A/[lg(nM)],线性相关系数为0.994。该胆固醇传感芯片具有较高的准确性,检测准确度达到了99.56%。     

人体唾液葡萄糖生物传感器

通过戊二醛交联法将葡萄糖氧化酶(GOD)固定在二茂铁(Fc)修饰的薄膜金电极上,制备了一种可用于检测人体唾液中葡萄糖含量的生物传感器。研究了不同扫描速度下二茂铁的电化学行为,以及工作电压、戊二醛浓度和酶固定量对传感器响应特性的影响。结果表明,利用戊二醛交联法制备的传感器检出限低、检测范围宽。在0~2 200μmol/L的葡萄糖标准浓度范围内,传感器灵敏度为21.45nA.μmol-1.cm-2(相关系数r=0.991 2),检出限为1μmol/L,响应时间5s。该结果可实现对唾液葡萄糖的检测,进而有望实现对血糖的检测。     

铂黑/二茂铁修饰MEMS电极的葡萄糖传感器

利用MEMS技术小批量加工了薄膜金电极。采用电化学沉积法在金电极表面修饰纳米铂黑颗粒,以有机功能性材料二茂铁作为电子媒介体,通过戊二醛-牛血清白蛋白共价交联固定葡萄糖氧化酶制得葡萄糖生物传感器。考察了不同修饰电极的电化学行为以及酶固定量和戊二醛浓度对传感器响应特性的影响。实验结果表明:该传感器响应时间仅为5s,在0.29V的低工作电压下,线性测量范围可达到0.5～22mmol/L,灵敏度为50.35μA/(cm2.mmol.L-1),相关系数为0.9925,差异系数为4.28%。     

ZnO修饰多针-板结构负电晕放电气体传感器北大核心

基于负电晕放电原理的气体传感器利用局部高压电场将目标气体电离,根据电离特性对气体进行识别。采用MEMS技术制备硅尖阵列电极,利用电喷ZnO纳米颗粒对电极表面进行修饰,结合金平板正电极构建了多针-板结构电晕放电气体传感器。研究了电极间距对传感器负电晕放电特性的影响,综合考虑起晕电压、信号输出范围及稳定放电范围,优化电极间距为100μm。测试了在-0.70 kV放电电压下传感器对乙酸气体的敏感特性。该传感器对乙酸气体的响应灵敏度约为1.05 mV/10-6,理论检测限(三倍噪声)约为8.6×10-6,测试范围内传感器响应同乙酸气体体积分数近似呈线性关系。实验结果表明,ZnO纳米颗粒修饰减小了放电尖端曲率半径,增加了放电尖端个数,消除了硅尖阵列之间高度和顶端曲率半径的差异,从而有效降低了起晕电压,提高了传感器对乙酸气体响应灵敏度及电晕放电的稳定性。     

基于GMR生物传感器的甲胎蛋白检测

采用磁控溅射、光刻、离子束刻蚀和剥离工艺等工艺和方法,制备了多层膜结构的巨磁阻(GMR)生物传感器件,并利用此种传感器来检测甲胎蛋白。在传感器表面通过生物处理固定甲胎蛋白单克隆抗体(McAb1)作为探针,以捕获目标抗原———甲胎蛋白。用直径1μm的超顺磁磁珠标记目标抗原。当传感器表面抗体将目标抗原捕获后,磁珠标记即被固定在GMR传感器的表面。垂直于传感器表面施加230 Oe(1 Am-1=4π×10-3 Oe)的磁场,即可检测到由磁珠产生的信号。本实验对质量浓度为1 ng/mL的甲胎蛋白进行了检测,得到了信号为0.29～0.34Ω的电阻变化值。此种检测方法可用于诊断原发性肝癌。     

基于聚硫堇修饰金电极构建无标记电流型免疫传感器检测冈田酸

在金电极表面利用循环伏安法电聚合修饰聚硫堇(PTh),由于PTh表面具有大量的-NH2官能团,可通过与戊二醛发生席夫碱反应固定抗体,基于抗原-抗体特异性免疫反应的原理,构建一种无标记电流型免疫传感器,实现对冈田酸(OA)的定量检测。用该免疫传感器以方波伏安法(SWV)对OA浓度进行检测,在0.1～100μg/L范围内,免疫反应前后峰值电流差值?i_p与OA浓度对数值lgCOA具有良好的线性关系,线性回归方程为?i_p=4.1915+2.1679lgCOA,线性相关系数R²=0.9578,检测限为18.1 ng/L(S/N=3)。该传感器检测限低、线性工作区间宽、操作简便。     

基于氧化石墨烯微纳光纤的狂犬病毒免疫传感器

提出一种基于氧化石墨烯(GO)微纳光纤的生物传感器，将其用于狂犬病毒(RV)的免疫检测研究。首先，将标准单模光纤通过熔接机放电形成双锥形光纤，再对双锥形光纤进行熔融拉锥制作出高灵敏度的微纳光纤。然后，在微纳光纤表面修饰GO，并将RV抗原固定于该传感器表面，用于对RV抗体的特异性检测实验。实验结果表明：该生物传感器对RV抗体的检测范围为200 fg/mL～1 ng/mL，检测极限(LOD)约为225.56 fg/mL，其检测灵敏度约为1.099 nm/log(mg·mL^-1)，解离系数约为2.92×10^-11 M；当用于不同的抗体溶液样本和RV阳性血清的对照检测及临床检测时，该免疫传感器对前者的响应非常微弱，而对后者有明显的响应，说明其对RV抗体具有良好的特异性。基于GO修饰微纳光纤的免疫传感器具有制作简单、微纳尺寸、灵敏度高、成本低等优点。     

双侧抛D型光子晶体光纤表面等离子体温度传感器

为了降低传感器结构复杂度和提高传感器温度灵敏度,提出一种双侧抛D型、包层为正六边形和正八边形的光子晶体光纤表面等离子共振(SPR)温度传感器,利用COMSOL Multiphysics有限元仿真软件分别研究了偏振方向、空气孔径、银膜厚度对传感器的性能影响,找出各项数据的最优值,并以此为基础对传感器的温度传感特性进行了分析。仿真结果表明:在x偏振方向模式下,当包层空气孔d1=1μm、d2=0.5μm,金属银膜厚度tAg=35 nm时,传感器的性能最优,在0~120℃时传感器的温度灵敏度最高可达-7.99 nm/℃。     

氧化石墨烯修饰的色散拐点长周期光纤光栅的折射率传感特性

研究了氧化石墨烯(Graphene Oxide,GO)修饰的色散拐点长周期光纤光栅(Dispersion-Turning-Point Long Period Fiber Grating,DTP-LPFG)传感器,分析了其光谱特性及对外部折射率的灵敏度特性。利用准连续KrF激光器在载氢单模石英光纤上制作周期约为136μm的DTP-LPFG,采用氢键结合的方式将GO涂覆于光栅表面,构成基于GO修饰的DTP-LPFG传感器。实验结果表明:随着GO在DTP-LPFG表面的沉积,其双谐振峰的左峰发生蓝移,右峰发生红移,双峰间距增大;在1.33~1.38折射率范围内,该传感器在涂覆GO后,谐振双峰间距变化量的折射率灵敏度约为831.89nm/RIU,较未修饰GO的DTP-LPFG提高了1.05倍。     

基于标准CMOS工艺的新型pH值传感器

基于0.6μmCMOS工艺设计了一种新型的pH值传感器。多晶硅和双层金属电极形成复合的悬浮栅结构,Si3N4钝化层作为敏感层。传感单元为W/L=500μm/20μm的PMOS管,其阈值电压随溶液pH值线性变化,并通过恒定PMOS管源漏电压和源漏电流控制电路转换成PMOS管源电压线性输出。PMOS管源电压线性输出范围达到4.6V,很好满足在不同pH值溶液中测试的要求。采用波长396nm紫外灯管照射来消除浮栅上电荷,增大阈值电压并有效调整溶液栅电压线性区工作范围。紫外照射后溶液栅电压可偏置在0V,减少溶液中噪声影响。CMOSpH值传感器的平均灵敏度为35.8mV/pH。     

热载流子应力下n-MOSFET线性漏电流的退化

研究了不同沟道和栅氧化层厚度的n-M O S器件在衬底正偏压的VG=VD/2热载流子应力下,由于衬底正偏压的不同对器件线性漏电流退化的影响。实验发现衬底正偏压对沟长0.135μm,栅氧化层厚度2.5 nm器件的线性漏电流退化的影响比沟长0.25μm,栅氧化层厚度5 nm器件更强。分析结果表明,随着器件沟长继续缩短和栅氧化层减薄,由于衬底正偏置导致的阈值电压减小、增强的寄生NPN晶体管效应、沟道热电子与碰撞电离空穴复合所产生的高能光子以及热电子直接隧穿超薄栅氧化层产生的高能光子可能打断S i-S iO2界面的弱键产生界面陷阱,加速n-M O S器件线性漏电流的退化。     

The importance of electrochemistry-related etching in thegate-groove fabrication for InAlAs/InGaAs HFETs

For the first time, the surface metal on nonalloyed ohmic electrodes is found to significantly change the profiles of gate grooves, when resist openings are employed to monitor drain current during wet-chemical gate recess for sub-micron InAlAs/lnGaAs heterojunction field-effect transistors (HFETs). The surface metal of Ni enhances the etching rate in comparison with that in the absence of electrodes by a factor of 4 and 10, laterally and vertically, which is favorable to fabricate deep gate grooves with small side etching. The Pt surface metal, however, leads to preferential etching of InGaAs over InAlAs, which can be useful to realize large side etching. The existence of an electrochemistry-related etching component, which arises when the ohmic electrodes are present during recess etching, is considered to be responsible for these behaviors     

A 5.2 mW Self-Configured Wearable Body Sensor Network Controller and a 12 $mu$ W Wirelessly Powered Sensor for a Continuous Health Monitoring System

A self-configured body sensor network controller and a high efficiency wirelessly powered sensor are presented for a wearable, continuous health monitoring system. The sensor chip harvests its power from the surrounding health monitoring band using an Adaptive Threshold Rectifier (ATR) with 54.9% efficiency, and it consumes 12 ?W to implement an electrocardiogram (ECG) analog front-end and an ADC. The ATR is implemented with a standard CMOS process for low cost. The adhesive bandage type sensor patch is composed of the sensor chip, a Planar-Fashionable Circuit Board (P-FCB) inductor, and a pair of dry P-FCB electrodes. The dry P-FCB electrodes enable long term monitoring without skin irritation. The network controller automatically locates the sensor position, configures the sensor type (self-configuration), wirelessly provides power to the configured sensors, and transacts data with only the selected sensors while dissipating 5.2 mW at a single 1.8 V supply. Both the sensor and the health monitoring band are implemented using P-FCB for enhanced wearability and for lower production cost. The sensor chip and the network controller chip occupy 4.8 mm² and 15.0 mm², respectively, including pads, in standard 0.18 ?m 1P6M CMOS technology.     

Noise of electrode sensor in pulsating liquid flow

A periodic component of the ac electrode voltage (electrode noise) is revealed in experiments. The frequency of the periodic component is equal to the pulsation frequency of the flow velocity of liquid in which the electrode sensor is immersed. For the electrode sensor that moves in liquid such a component of the electrode noise may prevail and determine the sensitivity. The sensitivity of a sensor with stainless-steel electrodes with respect to the velocity pulsations is determined to be 1.2 × 10^?6 V s/m. Pulsations of the electrode potential can be interpreted using variations in the rate of electrochemical reaction on the electrode surface.     

Micro FET pressure sensor manufactured using CMOS-MEMS technique

The fabrication of a micro field effect transistor (FET) pressure sensor using the commercial 0.35 μm complementary metal oxide semiconductor (CMOS) process and a post-process has been investigated. The pressure sensor is composed of 16 sensing cells in parallel, and each sensing cell includes a suspended membrane and an NMOS. The suspended membrane is the movable gate of the NMOS. The pressure sensor needs a post-process to obtain the suspended membrane after the CMOS process. The post-process employs etchants to etch the sacrificial layers to release the suspended membrane, and then a low-pressure chemical vapor deposition (LPCVD) parylene is used to seal the etching holes in the pressure sensor. The pressure sensor produces a change in current when applying a pressure to the sensing cells. Experimental results show that the pressure sensor has a sensitivity of 0.022 μA/kPa in the pressure range of 0–500 kPa.     

0.86-nm CET Gate Stacks With Epitaxial$hboxGd_2hboxO_3$High-$k$Dielectrics and FUSI NiSi Metal Electrodes

In this letter, ultrathin gadolinium oxide$(hboxGd_2hboxO_3)$high-$k$gate dielectrics with complementary-metal-oxide-semiconductor (CMOS)-compatible fully silicided nickel-silicide metal gate electrodes are reported for the first time. MOS capacitors with a$hboxGd_2hboxO_3$thickness of 3.1 nm yield a capacitance equivalent oxide thickness of$ CET = hbox0.86 hboxnm$. The extracted dielectric constant is$k = hbox13-hbox14$. Leakage currents and equivalent oxide thicknesses of this novel gate stack meet the International Technology Roadmap for Semiconductors targets for the near term schedule and beyond.     

Growth of Metal–Metal Oxide Nanostructures on Freestanding Graphene Paper for Flexible Biosensors

Flexible biosensors are of considerable current interest for the development of portable point‐of‐care medical products, minimally invasive implantable devices, and compact diagnostic platforms. A new type of flexible electrochemical sensor fabricated by depositing high‐density Pt nanoparticles on freestanding reduced graphene oxide paper (rGOP) carrying MnO₂ nanowire networks is reported. The triple‐component design offers new possibilities to integrate the mechanical and electrical properties of rGOP, the large surface area of MnO₂ networks, and the catalytic activity of well‐dispersed and small‐sized Pt nanoparticles prepared via ultrasonic‐electrodeposition. The sensitivity and selectivity that the flexible electrode demonstrates for nonenzymatic detection of H₂O₂ enables its use for monitoring H₂O₂ secretion by live cells. The strategy of structurally integrating metal, metal oxide, and graphene paper will provide new insight into the design of flexible electrodes for a wide range of applications in biosensing, bioelectronics, and lab‐on‐a‐chip devices.     

Characteristics of HfO/sub 2/ pMOSFET prepared by B/sub 2/H/sub 6/ plasma doping and KrF excimer laser annealing

The electrical characteristics of HfO/sub 2/ pMOSFETs prepared by B/sub 2/H/sub 6/ plasma doping and excimer laser annealing were investigated. Various metal gate electrodes were evaluated to protect the high-/spl kappa/ oxide during laser irradiation. Although the aluminum gate electrode showed superior reflectivity to the laser, the equivalent oxide thickness was increased due to the interaction between aluminum and HfO/sub 2/, which resulted in reduced capacitance. In contrast, the Al-TaN stacked gate showed good reflectivity up to laser energy of 500 mJ/cm/sup 2/ and improved capacitance was obtained compared with the Al gate. For the first time, the electrical characteristics of a HfO/sub 2/ pMOSFET with an Al-TaN gate fabricated by plasma doping and excimer laser annealing were demonstrated. It was also demonstrated that plasma doping and excimer laser annealing combined with a metal gate could be applied for high-/spl kappa/ oxide MOSFET fabrication.     

Metal gate work function engineering on gate leakage of MOSFETs

We present a systematic study of tunneling leakage current in metal gate MOSFETs and how it is affected by the work function of the metal gate electrodes. Physical models used for simulations were corroborated by experimental results from SiO/sub 2/ and HfO/sub 2/ gate dielectrics with TaN electrodes. In bulk CMOS results show that, at the same capacitance equivalent oxide thickness (CET) at inversion, replacing a poly-Si gate by metal reduces the gate leakage appreciably by one to two orders of magnitude due to the elimination of polysilicon gate depletion. It is also found that the work function /spl Phi//sub B/ of a metal gate affects tunneling characteristics in MOSFETs. It is particularly significant when the transistor is biased at accumulation. Specifically, the increase of /spl Phi//sub B/ reduces the gate-to-channel tunneling in off-biased n-FET and the use of a metal gate with midgap /spl Phi//sub B/ results in a significant reduction of gate to source/drain extension (SDE) tunneling in both n- and p-FETs. Compared to bulk FET, double gate (DG) FET has much lower off-state leakage due to the smaller gate to SDE tunneling. This reduction in off-state leakage can be as much as three orders of magnitude when high-/spl kappa/ gate dielectric is used. Finally, the benefits of employing metal gate DG structure in future CMOS scaling are discussed.