Heng Yuan

Highly sensitive nano-porous lattice biosensor based on localized surface plasmon resonance and interference

We propose a design for a highly sensitive biosensor based on nanostructured anodized aluminum oxide (AAO) substrates. A gold-deposited AAO substrate exhibits both optical interference and localized surface plasmon resonance (LSPR). In our sensor, application of these disparate optical properties overcomes problems of limited sensitivity, selectivity, and dynamic range seen in similar biosensors. We fabricated uniform periodic nanopore lattice AAO templates by two-step anodizing and assessed their suitability for application in biosensors by characterizing the change in optical response on addition of biomolecules to the AAO template. To determine the suitability of such structures for biosensing applications, we immobilized a layer of C-reactive protein (CRP) antibody on a gold coating atop an AAO template. We then applied a CRP antigen (Ag) atop the immobilized antibody (Ab) layer. The shift in reflectance is interpreted as being caused by the change in refractive index with membrane thickness. Our results confirm that our proposed AAO-based biosensor is highly selective toward detection of CRP antigen, and can measure a change in CRP antigen concentration of 1 fg/ml. This method can provide a simple, fast, and sensitive analysis for protein detection in real-time.

MOSFET–BJT hybrid mode of the gated lateral bipolar junction transistor for C-reactive protein detection

In this study, we propose a novel biosensor based on a gated lateral bipolar junction transistor (BJT) for biomaterial detection. The gated lateral BJT can function as both a BJT and a metal-oxide-semiconductor field-effect transistor (MOSFET) with both the emitter and source, and the collector and drain, coupled. C-reactive protein (CRP), which is an important disease marker in clinical examinations, can be detected using the proposed device. In the MOSFET-BJT hybrid mode, the sensitivity, selectivity, and reproducibility of the gated lateral BJT for biosensors were evaluated in this study. According to the results, in the MOSFET-BJT hybrid mode, the gated lateral BJT shows good selectivity and reproducibility. Changes in the emitter (source) current of the device for CRP antigen detection were approximately 0.65, 0.72, and 0.80 μA/decade at base currents of -50, -30, and -10 μA, respectively. The proposed device has significant application in the detection of certain biomaterials that require a dilution process using a common biosensor, such as a MOSFET-based biosensor.

Sensitivity Alterable Biosensor Based on Gated Lateral BJT for CRP Detection

In this paper, a biosensor based on a gated lateral bipolar junction transistor (BJT) is proposed. The gated lateral BJT can function as both a metaloxide-semiconductor field-effect transistor (MOSFET) and a BJT. By using the self-assembled monolayer (SAM) method, the C-reactive protein antibodies were immobilized on the floating gate of the device as the sensing membrane. Through the experiments, the characteristics of the biosensor were analyzed in this study. According to the results, it is indicated that the gated lateral BJT device can be successfully applied as a biosensor. Additionally, we found that the sensitivity of the gated lateral BJT can be varied by adjusting the emitter (source) bias.

P2.3.3 VOC gas detection using solvatochromic dye coated side polished optical fiber

A high sensitive volatile organic compounds (VOCs) gas sensor using side-polished optical fiber was developed in this study. The surface of the side-polished optical fiber coupled with the coated solvatochromic dye which has charge-transfer (CT) characters. Dimethylamine, acetic acid, toluene, benzene, and ethanol 5-types of VOCs gases were detected in this study. The different polarities of the VOCs gases cause different CT and different effective refractive index changings of the sensing membrane, which can lead to the resonance wave length of the side-polished optical fiber changed. According to the results, we found that the side-polished optical fiber sensor has good selectivity and high sensitivity properties.

Nanoporous aluminum anodic oxide-based optical biosensor for real-time detection of Troponin T

A highly sensitive and real-time monitoring biosensor detecting Troponin T was developed using a nanoporous aluminum anodic oxide (AAO) layer as a sensing membrane. Troponin T is known as an unusual myocardial injury marker, and as a protein that forms the complexes with Troponin I, and Troponin C, which control muscle contraction. The device using interferometry and localized surface plasmon resonance (LSPR) phenomenon has high sensitivity and selectivity compared with a single sensing principal device. To fabricate a sensing membrane, two-step anodizing method was conducted. Au deposition was conducted to induce the LSPR phenomenon and to immobilize Troponin T antibody by SAM method. A real time sensing system was consisted of optical spectrometer and an optical fiber reflectance probe. We confirmed that the developed biosensor system had high sensitivity to detect Troponin T.

Design Optimization of Silicon-based Junctionless Fin-type Field-Effect Transistors for Low Standby Power Technology

Recently, the junctionless (JL) transistors realized by a single-type doping process have attracted attention instead of the conventional metal-oxide-semiconductor field-effect transistors (MOSFET). The JL transistor can overcome MOSFETs problems such as the thermal budget and short-channel effect. Thus, the JL transistor is considered as great alternative device for a next generation low standby power silicon system. In this paper, the JL FinFET was simulated with a three dimensional (3D) technology computer-aided design (TCAD) simulator and optimized for DC characteristics according to device dimension and doping concentration. The design variables were the fin width (Wfin), fin height (Hfin), and doping concentration (Dch). After the optimization of DC characteristics, RF characteristics of JL FinFET were also extracted.

Novel Biosensor Based on MOSFET-BJT Hybrid Mode of Gated Lateral Bipolar Junction Transistor for C-reactive Protein Detection

In this paper, a biosensor based on a gated lateral bipolar junction transistor (BJT) was proposed. The gated lateral BJT can function as both a metal-oxide-semiconductor field-effect transistor (MOSFET) and a BJT. By using selfassembled monolayer (SAM) method, the CRP antibodies were immobilized on the floating gate of the device as the sensing membrane. Through the experiment, the characteristics of the gated lateral BJT for biomaterials detection were analyzed in this study. According to the results, under the MOSFET-BJT hybrid mode of the device, when the base current was -10 μA, the sensitivity was approximately 0.80 μA/decade, and the sensing limit was approximately 1 pmol/L. Meanwhile, the gated lateral BJT can be successfully applicable as sensitive biosensor.

Gated lateral BJT gas sensor for toluene gas detection under room temperature condition

A room temperature gas sensor for toluene detection using gated lateral bipolar junction transistor (BJT) was reported in this study. The proposed device which matches a metal oxide semiconductor field effect transistor (MOSFET) and a BJT was fabricated in a standard 0.35-μm logic process with one-poly and four-metal structure. Then, the 4-aminophthalimide (4AP) dye as a kind of solvatochromic dye which has the charge-transfer (CT) characteristic was used as the sensing membrane. The 4AP dye was immobilized on the floating gate of the gated lateral BJT using self-assembled monolayer (SAM) method. We set this kind of gated lateral BJT operating in the MOSFET-BJT hybrid mode. The electric current changes of the lateral BJT with respect to toluene gas concentrations were obtained by using semiconductor test & analyzer (STA).

Threshold voltage changed by floating gate control in electrolyte-insulator-semiconductor structure

A method for controlling the threshold voltage which has a significant problem in ion-sensitive transistors (IST) with floating gate structures was proposed in this study. Gated lateral pnp-type bipolar junction transistor (BJT) was used in our experiment and was immerged in ionic solution. The experiment results indicated that under a large negative gate bias condition, the threshold voltage can shift in normal state with specific bias. Moreover, we discussed the reasons for the changing phenomenon of threshold voltage in dielectric of gated lateral BJT in electrolyte.

VOC Gas Sensing Based on the BJT Mode of Gated LBJT Device

Volatile organic compounds (VOCs) gas sensor based on gated lateral bipolar junction transistor (LBJT) was developed in this study. The device was fabricated using 0.35-μm logic process by Magnachip-Hynix Co. Ltd. under the Integrated Circuit Design education Center Multi Project Wafer (IDEC-MPW) program. Solvatochromic dye as the sensing membrane was coated on the floating gate of the device. A semiconductor test and analyzer (STA-EL421, ELECS) was used to measure the sensing results. Following the results, we found that the sensing device which used the gated LBJT device has fast responsibility and reversibility to VOC gases (acetone etc.).