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With helps of advancing CMOS technology, ISFETs have achieved great success. However, CMOS-based ISFETs are also suffering problems of scaling attenuation and threshold voltage offset. These problems mainly result from the architecture used to adapt standard CMOS process. To deal with these, we developed a novel CMOS ISFET configuration, namely, 3D-T-ISFET, by building a truncated architecture to expose CMOS process-inherent TiN thin film as the sensing interface. Due to the electrical conductivity of TiN, the signal from the environment can bypass the sensing dielectric and couple to the transistor effectively through the electrical double layer capacitance. Based on our experiments, as the footprint of 8.52 μm2, a 3.21-fold ΔID/pH improvement can be achieved by developed 3D-T-ISFET. At the same time, the 3D-T-ISFET has an about 1.65-fold improvement in SNR compared to the traditional 2D-ISFET. Compared to the 2D-ISFET in a state-of-the-art design, therefore, 3D-T-ISFET exhibits a scaling attenuation-free behavior and becomes less vulnerable to the non-idea effects brought by trapped charges.

As the CMOS-based ion-sensitive field-effect transistor (ISFET) is scaling down to achieve a compact sensing array with high spatial resolution, reduction of sensing layer capacitance attenuates capacitive coupling efficiency of environmental input signals and decreases sensitivity performance. To address this issue, a concept of three-dimensional (3D) sensing structure is proposed and examined in this study. This can increase the sensing layer capacitance for a given footprint area. Based on our designs, a series of 3D sensing structures can be implemented with a standard CMOS foundry service and CMOS-compatible post processes. Our experimental results show that an $8.5^{2}\mu \text{m}^{2}$ footprint design of the 3D sensing structure can obtain approximately 2-fold increase in transconductance compared with a traditional ISFET with the same footprint. This enables pH sensitivity to be improved 1.5-fold in current response and 1.15-fold in voltage response. Therefore, the proposed 3D-structure ISFET can pave the way toward an ISFET sensing array with high sensitivity and high spatial resolution.

We investigate liquid dielectrophoresis (LDEP) to implement field-effect pumps (FEPs) that drive liquids from source, via gate, toward drain electric fields between parallel plates without external pumps or the problem of dead volume. The appropriate gate electric field establishes a wall-less virtual microchannel to transfer the liquid from source to drain with an adjustable flow rate (Q) controlled by the difference of the square of the electric field strength (ΔE2DS). Analogous to field-effect transistors (FETs), the FEPs can operate in a "linear", "transition" or "saturation" region depending on ΔE2GD and ΔE2DS. With a sufficient ΔE2GD and a small ΔE2DS, the FEPs operated in the linear region where Q was linearly proportional to ΔE2DS and inversely proportional to the flow resistance R that was mainly determined by the length (L), width (W) and height (H) of a stable and fully-occupied virtual microchannel. With an insufficient ΔE2GD and a moderate to large ΔE2DS, narrowing, tapering and even pinch-off of virtual microchannels were observed, which increased R and changed the operation into the transition or saturation region. A field-effect stream merger regulating two streams was built based on two FEPs with shared gate and drain electrodes. The versatility of FEPs was demonstrated with preliminary studies on whole blood and particle solutions.

Machine learning has become an emerging method for next-generation smart technologies. It also promotes a development-paradigm shift in sensing technologies, which are essential in various smart applications. In this paper, we develop a data-driven method for a monolithic ion-sensitive field-effect transistor (ISFET) to have both photon and pH bi-detection capabilities simultaneously. The proposed methods are executed based on sequential-bias-reconfiguration of the ISFET. Utilizing support vector machine and back-propagation neural network, the photocurrent and ion-induced current can be calculated and decoupled. To evaluate the proposed method, semi-quantification by classification methods and quantification by regression methods are both examined. This paper has experimentally demonstrated the dual-detection capability of a pH range from 5 to 9 and an intensity range from 0 to $760~\mu \text{W}$ /cm2 with prediction error less than 1.5%. To fulfill low-computation requirement for applications, we further optimize the proposed algorithm by feature reduction to balance performances between accuracy, complexity of data acquisition, and data processing. With the developed machine-learning sensing device, therefore, we successfully demonstrate potentials of data-driven sensing devices in future applications.

A solution-based ferroelectric relaxor poly(vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene) terpolymer, P(VDF–TrFE–CTFE), is employed in a metal-insulator-semiconductor (MIS) capacitor as a high-k dielectric material. Based on experimental characterizations, the capacitance of the MIS structure is decreased with P(VDF-TrFE-CTFE) thickness reduced. Examined by electrical characterizations, an equivalent interface layer at the P(VDF-TrFE-CTFE)/silicon interface is proposed in this work. This shows that the P(VDF–TrFE–CTFE) film thickness is an important factor while using it as a high-k dielectric material in devices. At the same time, experimental results also show a low remnant polarization and low coercive field of 1.23 μC/cm2 and 0.176 MV/cm, respectively. This indicates operating frequency is also a factor of its effective dielectric constant. In our experimental results, the maximum dielectric constant is 32.4 at 1 kHz with 2900 nm film thickness. For applications in different organic electronics, therefore, this study demonstrates that P(VDF–TrFE–CTFE) is a frequency/thickness dependent high-k dielectric material.

Microfluidic preparation is one of important functions in miniaturized diagnosis systems. However, most of existing microfluidic devices require external driving sources which occupies the majority of system size and weight. To address the insufficiency, this work provides an active fluidic pumping and filtration mechanism by travelling-wave electroosmosis (TWEO). Based on superposition of TWEO and induced-chard electroosmosis (ICEO), our numerical simulations show particles are tend to be trapped within surface microelectrodes. As driven by TWEO, thus, particle pumping and particle trapping effect are controllable by the particle size and applied electrical potential. Experimentally, in our implemented devices, 6 μm and 10 μm beads are fully trapped with the applied potential larger than 0.75 V. In addition, 91.9% 1 μm beads flowed thorough as device driven at 0.75 V and 82.3% 1 μm beads trapped on surface electrodes as device drive at 1.50 V. Finally, the HL-60 cancer cells are conducted to demonstrate the potential to handle a real-cell sample for a particle-filtration function in the developed device. The developed device provides a promising on-chip method to achieve the active filtering and pumping function with low-power characteristics for future miniaturized healthcare systems.

In this work, we modified the single layer graphene by nitrogen modification through the low-damage plasma treatment (LD-plasma). The electronic transport characteristics for different modified parameters under aqueous environment were performed by Agilent semiconductor analysis B1500A. We choose potassium chloride (KCl) as our electrolyte. Based on the experimental results, the Dirac point is shifted linearly with the concentration of KCl. At the same time, the experimental results also show that the behaviors of 1-min and 3-min modifications are quite different between each other because of modification to graphene structure. As a consequence, this work shows an opportunity of being an ionic sensor with the developed nitrogen-doped graphene.

In this work, we study surface functionalization effects of artificially stacked graphene bilayers (ASGBs) to control its wetting properties via low-damage plasma. The ASGBs were prepared on a SiO2/Si substrate by stacking two monolayer graphene, which was grown by chemical vapor deposition. As a result, the low-damage plasma functionalization of ASGBs could hold both the key characteristics of surface functionalization and electrical transport properties of graphene sheets. To characterize ASGBs, Raman and x-ray photoelectron spectroscopy (XPS) were used to determine the degree of defect formation and functionalization. Meanwhile, the degree of the wettability of the ASGBs surface was determined by optical contact angle (CA) measurements. Based on experimental results, the compositional ratio of C-OH + COOH was found to increase 67% based on the analysis of XPS spectra after low-damage plasma treatment. This treatment effect can also be found with 75.3% decrease in the CA of water droplet on graphene. In addition, we found that the ratio of 2D/(D + G') in Raman spectra shows strong correlation to the measured CA; it can be a reliable indicator of ASGBs surface wettability modification. This work showed that we obtained a higher degree functionalization of ASGBs without degrading the under-layer structure of ASGBs due to the moderate low-damage plasma treatment. The presented process technique of controllable wettability through low-damage plasma treatment can be employed for potential application in graphene-based sensors/devices.

Manipulation of transport hysteresis on graphene-based field effect transistors and understanding electron transfer between graphene and organic solution are important for the development of graphene-based sensor device. Several papers regarding to the researches about hysteresis in graphene devices have been published, which are significant to graphene-based device[1 -3 ]. However, there are seldom papers focus on graphene with one-side organic solution which has different relative permittivity and various dipole moment constant. This means that graphene suspended in liquid which eliminates the effect of substrate and leaves graphene and liquid with pure structure. Therefore, we do further researches on the graphene-based device and explore the relationship between graphene and solution. In our research, the structure of the device is shown in Figure1, which includes two gold electrodes used for drain and source separately and the etched area which contains two larger rectangular area used for injecting liquid and one main trench with some pillars used for suspending graphene. When measuring each set of data, we did experiments in ambient environment and used the same suspended-graphene device to control the influence of the fabrication deviation, such as the contact resistance or the sheet resistance of bilayer graphene. Figure2(a) shows the SEM image of suspended graphene on the main trench and the significant differences can be seen between the parts where the graphene exists and does not exist, which proves the presence of suspended graphene. We do the same measurement the transport hysteresis in the device by using several solvent includes isopropanol (IPA), ethonal and dimethylacetamide (DMAC). Figure 2(b) shows the different hysteresis situations of three different solutions observed in this work. In the picture, the solid line illustrates the drain current change with the forward voltage which means voltage swept from -1V to 1V and the dotted line depicts the drain current alter with reverse scanning voltage called backward voltage. The value of hysteresis is defined as the difference between the voltage value corresponding to the lowest value of the forward curve and that of the backward curve，which is equal to the change between Dirac point. As shown in Figure 3(a), the difference between the hysteresis in the organic solution of various permittivity shows an almost curve correlation. Hysteresis value decreases as the dielectric constant drops, which can be explained by less charge trapping will cause smaller hysteresis. At the same time, the variety between the hysteresis of solvent with various dipole moment displays line with more obvious arc, which is shown in Figure3(b). These observations are interesting phenemonon which may related to the change on electrostatic environment of graphene[1] and the process of the competition between charge trapping effect and capacitive gating effect[2]. In conclusion, we made several experiments to explore the relationship between graphene-based device and solvent with different electrical characteristics and found some interesting results of the difference between Dirac point regarding to permittivity and dipole moment. This characteristic may be used for judging the purity of organic solvents and other chemical or biological sensing application. Furthermore, it contribute to the fundamental development of relationship between graphene-based devices and different solvents. [1]Philipp Klar and Cinzia Casiraghi. Raman spectroscopy of graphene in different dielectric solvents[J].Phys. Status Solidi C,2010,7:2735-2738. [2]Wang, H.; Wu, Y.; Cong, C.; Shang, J.; Yu, T., Hysteresis of Electronic Transport in Graphene Transistors. ACS Nano 2010,4(12), 7221-8 [3]Uysal, A.; Zhou, H.; Feng, G.; Lee, S. S.; Li, S.; Fenter, P.; Cummings, P. T.; Fulvio, P.F.; Dai, S.; McDonough, J. K.; Gogotsi, Y. Structural origins of potential dependent hysteresis at the electrified graphene/ionic liquid interface. J. Phys. Chem. C,2013,118, 569-574. Figure 1

This article reviews optical biosensors and their integration with microfluidic channels. The integrated biosensors have the advantages of higher accuracy and sensitivity because they can simultaneously monitor two or more parameters. They can further incorporate many functionalities such as electrical control and signal readout monolithically in a single semiconductor chip, making them ideal candidates for point-of-care testing. In this article, we discuss the applications by specifically looking into point-of-care testing (POCT) using integrated optical sensors. The requirement and future perspective of integrated optical biosensors for POC is addressed.

This work investigates temperature effects of low-damage plasma (LD plasma) treatment for nitrogen-modification graphene. Different from traditional nitrogen-modification graphene achieved by ammonia plasma, in this work, it is accomplished by the LD plasma with pure nitrogen. The analyses of Raman and XPS spectra show that the concentration of modified nitrogen raised with the substrate temperature from room temperature to 125 °C. However, the decrease of nitrogen-modification ratio occurred as the substrate heating temperature higher than 150 °C. This might be resulted from the diffusion mechanism of ion species away from the graphene surface. Observed from these experimental results, the highest nitrogen doping ratio on artificial-stacked graphene bilayers (ASGBs) sample occurred at the substrate-heating temperature of 125 °C. Based on the developed method, advantages of nitrogen-modification graphene with less contamination can be achieved for further applications.

Traditionally, graphene-based field effect transistors comprise graphene flakes lying on SiO2 substrate. On the other hand, suspended graphene structure can help investigate the intrinsic properties of graphene and even show improved sample quality. There have been several publications relating to the researches about transport hysteresis in graphene devices [1-3], which are important for the development of graphene-based sensor. However, there are seldom paper talking about graphene with one-side liquid structure, which means the effects of the substrate can be eliminated, leaving the structure of pure graphene and liquid. Therefore, we can further explore the intrinsic characteristics of graphene, such as hydrophilic or hydrophobic surface properties. In this work, we used the device structure as shown in Figure 1 to present an investigation compared with the previous device. The device of Figure 1 contains two gold contacts for drain/source electrodes, and the etched area which includes two larger regions for liquid injection and the main trench with some pillar for suspended graphene. We began by measuring the transport hysteresis in the device without trench, and then do the same measurement but using the device for suspended graphene. The solution gate voltage is swept from -1V to 1V in order to avoid any reaction, and both devices are in ambient environment. Figure 2 shows the different hysteresis directions observed in this work, which means that there are some differences between the carrier transport mechanism of these two devices. As shown in Figure 3, the magnitude of the hysteresis in gate voltage is quite different in the two devices, which it’s larger in suspended-graphene device than in normal device. Besides, the drain currents in two devices also show a large difference, which may result from the fabrication deviation, such as the contact resistance or the sheet resistance of bilayer graphene. On the other hand, the difference between the Dirac point (VDirac) in the potassium chloride (KCl) solution of various concentration shows an almost linear dependent relationship if we plot the concentrations on the logarithmic scale, as shown in Figure 4. It is believed that the more charge trapping will cause larger hysteresis; however, in this work we found that the magnitude of hysteresis on suspended graphene device is anomalously larger than on-substrate graphene. We suppose that this result is related to the air/graphene/ion liquid structure associated with the intrinsic properties of graphene surface. The second observation of the reduction hysteresis by increasing the solution concentration is also an interesting phenomenon, which may relates to the process of the competition between charge trapping effect and capacitive gating effect. [1] In conclusion, we compared the electrical characteristics shown by two different structures of graphene-based field effect transistor in this work, and found some interesting results of the transport hysteresis relating to device structure and ion concentration. This development has potentials for the chemical or biological sensing application. Furthermore, it can contribute to the fundamental researches about the interaction on the interface between graphene and solution. [1] Wang, H.; Wu, Y.; Cong, C.; Shang, J.; Yu, T., Hysteresis of Electronic Transport in Graphene Transistors. ACS Nano 2010,4(12), 7221-8. [2] Uysal, A.; Zhou, H.; Feng, G.; Lee, S. S.; Li, S.; Fenter, P.; Cummings, P. T.; Fulvio, P.F.; Dai, S.; McDonough, J. K.; Gogotsi, Y. Structural origins of potential dependent hysteresis at the electrified graphene/ionic liquid interface. J. Phys. Chem. C2013,118, 569-574. [3] Shih, C.-J., Paulus, G. L. C., Wang, Q. H., Jin, Z., Blankschtein, D., Strano, M. S., Understanding Surfactant/Graphene Interactions Using a Graphene Field Effect Transistor: Relating Molecular Structure to Hysteresis and Carrier Mobility. Langmuir, 28(22) Figure 1

In this study, we investigate humidity sensing performance of an artificially stacked graphene bilayers (ASGBs). Compared with non-modified ASGBs, the humidity sensing response of the ASGBs modified by a low-damage plasma (LD-plasma) can be improved by 40% and sensing selectivity to ethanol can be enhanced by 35% in our experimental results. Under examinations of Raman and XPS, these improvements can be attributed to carboxyl and hydroxyl groups bonding on the ASGBs surface after LD-plasma treatments. As a consequence, the ASGBs π-electron characteristic, which offers the main sensing mechanism, are also modified by the bonding groups. Therefore, these modifications not only help adsorptions of water molecules but also improve humidity selectivity to ethanol and IPA. Based on these developments and characterizations, this work developed a LD-plasma modified ASGBs sensing material for humidity sensing applications.

Graphene nanodiscs (GNDs), functionalized using NH3 plasma, as charge trapping sites (CTSs) for non-volatile memory applications have been investigated in this study. The fabrication process relies on the patterning of Au nanoparticles (Au-NPs), whose thicknesses are tuned to adjust the GND density and size upon etching. A GND density as high as 8 × 1011 cm−2 and a diameter of approximately 20 nm are achieved. The functionalization of GNDs by NH3 plasma creates N H+ functional groups that act as CTSs, as observed by Raman and Fourier transform infrared spectroscopy. This inherently enhances the density of CTSs in the GNDs, as a result, the memory window becomes more than 2.4 V and remains stable after 104 operating cycles. The charge loss is less than 10% for a 10-year data retention testing, making this low-temperature process suitable for low-cost non-volatile memory applications on flexible substrates.

In order to diagnose acute myocardial infraction (AMI) quickly by detection of cTnI, silicon nanowire (Si-NW) transistor is chosen to be the bio-sensor. We demonstrate Si-NW biosensors coated with different dielectric materials to detect cTnI. Based on the experimental results of 14 nm SiO2 and 28 nm SiO2, it is found that high capacitance dielectrics contribute better sensitivity than that of low capacitance dielectrics. In addition, high-k material dielectrics stacked with ultrathin SiO2 sensing membrane structures are used for Al2O3 and HfO2 because SiO2 has better compatibility with 3-Aminopropyltriethoxysilane (APTES). The results show that high-k stacked structure improve the sensitivity. Based on this work, the proposed Si-NW biosensor structure is experimentally demonstrates a good potential for future applications in cTnI detections.

This paper presents a highly-integrated DNA detection SoC, where several kinds of cantilever DNA sensors, a readout circuit, an MCU, voltage regulators, and a wireless transceiver, are integrated monolithically in a 0.35 μm CMOS Bio-MEMS process. The cantilever-based biosensors with embedded piezoresistors aim to transduce DNA hybridization into resistance variation without cumbersome labeling process. To improve detection sensitivity for low DNA concentration use, an oscillator-based self-calibrated readout circuit with high precision is proposed to convert small resistance variation ( of original resistance) of the sensor into adequate frequency variation and further into digital data. Moreover, its wireless capacity enables isolation of the sample solution from electrical wire lines and facilitates data transmission. To demonstrate the effectiveness of full system, it is applied to detect hepatitis B virus (HBV) DNA. The experimental results show that it has the capability to distinguish between one base-pair (1-bp) mismatch DNAs and match DNAs and achieves a limit of detection (LOD) of less than 1 pM.

In this paper, a metal-insulator-semiconductor (MIS) capacitor fabricated by using solution-based poly (vinylidene fluoride-trifluoroethylene-Chlorotrifluoroethylene) (P(VDF-TrFE-CTFE)) terpolymer as dielectric material was proposed. Dielectric properties of P(VDF-TrFE-CTFE) dielectric material such as high-k constant and low leakage current were demonstrated from the experimental results. The characterizations of P(VDF-TrFE-CTFE) dielectrics of various thicknesses were widely investigated. Notably, there is a thickness dependent dielectric constant characteristic in this study. The dielectric constant was increased with thickness increased. We assume the phenomenon were caused by the material crystallization phase and crystal size differences in different dielectric thickness and interface layer in series with P(VDF-TrFE-CTFE) dielectric.

A CMOS-based ion-sensitive field-effect transistor (ISFET) is designed, fabricated, and validated as a biosensor for protein diagnosis. Utilizing 180 nm foundry process, this work experimentally demonstrates the developed dual-gated ISFET biosensor array (128 by 128 devices) has capabilities to obtain statistical measurements of pH. Furthermore, it can be used to detect several specific biomarkers, i.e. cTnI, HbA1c and HBV-DNA, for cardiac diseases, diabetes and hepatitis B respectively. This work shows benefits of the nano-scale ISFET array for biosensing applications.

A micro-controller unit (MCU) assisted immunoassay lab-on-a-chip is realized in 0.35 $\mu$ m CMOS technology. The MCU automatically controls the detection procedure including blood filtration through a nonporous aluminum oxide membrane, bimolecular conjugation with antibodies attached to magnetic beads, electrolytic pumping, magnetic flushing and threshold detection based on Hall sensor array readout analysis. To verify the function of this chip, in-vitro Tumor necrosis factor- $\alpha$ (TNF- $\alpha$ ) and N-terminal pro-brain natriuretic peptide (NT-proBNP) tests are performed by this 9 mm $^{2}$ -sized single chip. The cost, efficiency and portability are considerably improved compared to the prior art.

To enhance the carrier mobility of all-inkjet-printed organic thin film transistors, we fabricated devices that incorporated poly(3-hexylthiophene) (P3HT) and carbon nanoparticles (CNPs). The fabricated devices had an on/off ratio of 104, which is one order less than that of pristine organic thin-film transistors (OTFTs). The maximum carrier mobility as high as 0.053 cm2/V-s was achieved for a CNP/P3HT weight–weight ratio of 7/100. This degree of mobility is 10 times greater than average mobility of pristine P3HT-OTFTs. X-ray diffraction and scanning electron microscopy images reveal that the carrier mobility was enhanced by reducing the injection barrier and enhancing the carrier injection. This work demonstrates the feasibility of all-inkjet-printed OTFT technology.

In the era of internet-of-things (IoT), sensors play important roles in every situation. It is of interest to reduce power consumption and chip size of sensing devices for mobile applications. In this work, we design and fabricate a solid-state device with chemical sensing and photodetecting, e.g. a dual-functional and reconfigurable sensor on single graphene field-effect transistor (GFET). Based on the single-layer graphene, this device couples these two solid-state sensing mechanisms. This graphene field-effect sensing device has a double-gate configuration, in which the electrolyte solution gate controls the top-gate GFET as the chemical sensor. At the same time, the bottom gate voltage is biased for noise reduction. In the developed GFET, a photodetector can also be created by taking advantage of high carrier mobility of graphene. As a consequence, applying bottom gate voltage is able to regulate charge induction on the graphene surface created by photo-excitation carriers inside the silicon substrate. Both of the two sensing mechanisms could be modulated under each gate independently. In other words, when one sensing mechanism is in operation mode, the signal current from the other sensing mechanism could be minimized by field-effect control, and vice versa. This phenomenon demonstrated the concept of electro-reconfigurable sensing devices. In this work, we demonstrate the photocurrent could be reduced by bottom gate voltage modulation when the device operating under chemical sensing mode. And the proposed electro-reconfiguration mechanism is investigated. This can be attributed to the ambipolar field-effect characteristic and surface electron traps of silicon dioxide layer as the bottom gate dielectric. In our experiments, the photodetector could be modulated by a +/- 7 V bottom gate voltage in the bottom-gate configuration. With the same device, the chemical sensor could be modulated by a +/- 500 mV solution gate voltage in the top-gate configuration. The newly developed electro-reconfigurable solid-state sensor has the advantages of small size, low cost and low operation voltage by utilizing the same device and sensing region. In addition, this device offers an alternative solution to photocurrent reduction in solid-state sensing devices by regulating photocurrent through field effect control. It would pave the way for real practice of IoT sensors and point-of-care testing devices. Figure 1

This work demonstrates a printable blending material, i.e., reduced graphene oxide (RGO) mixed with poly(methyl methacrylate) (PMMA), for formaldehyde sensing. Based on experimental results, 2% RGO/10% PMMA is an optimal ratio for formaldehyde detection, which produced a 30.5% resistance variation in response to 1000 ppm formaldehyde and high selectivity compared to different volatile organic compounds (VOCs), humidity, CO, and NO. The demonstrated detection limit is 100 ppm with 1.51% resistance variation. Characterization of the developed formaldehyde sensing material was performed by Fourier-transform infrared (FTIR) spectrometry, scanning electron microscopy (SEM), and Raman spectroscopy. Based on Raman spectroscopy, the basic sensing mechanism is the band distortion of RGO due to blending with PMMA and the adsorption of formaldehyde. This work establishes insights into the formaldehyde sensing mechanism and explores a potential printable sensing material for diverse applications.

We have fabricated organic thin film transistors (OTFTs) with a solution process by utilizing a novel wide bandgap conjugated polymer poly(N-(4-(9,9-dioctyl-fluoren-2-yl)phenyl)-N,N′,N′-triphenyl-l,4-phenylenediamine) (P1) as the active channel material. The transistor was constituted with a bottom-gate configuration, in which P1 was deposited on the substrate, SiO2 insulator served as the gate dielectric material and Ti/Au were used as the electrodes. The hole-transporting properties of the transistor were examined by analyzing the current–voltage (I–V) characteristics. The carrier mobility was 0.95 × 10−2 cm2 V−1 s−1 and the on/off current ratio was about 5.8 × 104. Moreover, the thin film of the novel polymer P1 exhibits very high transparency for visible light since the bandgap of P1 is 2.84 eV. The excellent electrical properties of the P1 based transistor and the nature of the high transparency of such a polymer suggest that the novel polymer P1 can potentially serve as a superior material for transparent organic electronics.

A Solar-Powered Sensor Module (SPSM) that uses low-cost capacitors as energy buffers to power wireless sensor motes was investigated. Compared to batteries or super capacitors, SPSM is particularly suitable for light-weight tasks since it buffers limited energy and powers up periodically. With our method, the energy charging time can be shortened to about 100 ms for a maximum power point tracking component, and the current of the output regulator can reach 71% efficiency.

This work presents a capacitive immunosensor using on-chip electrolytic pumping and magnetic washing techniques. The proposed device possesses the advantages such as simple operation, low power consumption, and portability. The proposed device was fabricated using typical micromachining process, and is suitable for mass-production. We also demonstrated the detection of N-Terminal pro-brain-Type natriuretic peptide (NT-proBNP) using the fabricated device integrated with a CMOS capacitance sensing chip. The proposed device potentially can be used as a portable system for point-of-care applications.

We report on a light-actuated digital microfluidics platform for real-time, isothermal helicase-dependent polymerase chain reaction (PCR). This platform is used to detect Herpes Simplex Virus Type 1 (HSV-1). Reagents in droplets are individually addressed, mixed, transported and arrayed on-chip before the PCR process. 16 droplets were formed from mixing 400 nl PCR master mix droplets with 35 nl HSV-1 viral lysate droplets, arrayed into a 4×4 matrix, and amplified simultaneously, all on chip. Amplification and detection of HSV-1 can be achieved within 45 minutes. No cross contamination was observed.

This paper presents a readout circuit for piezo-resistive sensing applications. It is based on a resistor-based oscillator which converts the resistance information into frequency domain. In the readout circuit, a mixer is employed to down-convert the oscillator frequency to lower frequency for subsequent digitization. The frequency down-conversion operation is equivalent to amplification in time which increases the system sensitivity to resistance variation. A frequency calibration loop is incorporated to set the mixer output frequency to a well-defined initial value. The readout circuit is fabricated in a TSMC 0.35-μm Bio-MEMS CMOS process platform. The oscillation frequency is 24 MHz, and the down-converted output frequency at mixer output is set to 100 kHz. The total readout circuit consumes 1 mW with 3-V supply. The system sensitivity is 7 kHz/Ω.

This is the first study to successfully achieve record DNA sensitivity (sub-ƒM) by self-aligned, maskless, dual-channel, and metal-gate-based thin-film transistor nano-wire FET. Both novel device architecture (dual-channel) and optimization of integration processes (microcrystalline silicon and self-aligned sidewall sub-50 nm critical dimension) of nano-wire FET enhance the sensitivity to biological entities substantially. Meanwhile, the proposed device is accomplished with an embedded VLSI CMOS circuit. It can thus offer high application potential to pH, protein, and DNA probing in SoC-based portable bioelectronics.

Poly(3-hexylthiophene), P3HT, has been widely used in organic electronics as a semiconductor material. It suffers from the low carrier mobility characteristics. This limits P3HT to be employed in applications. Therefore, the blending semiconductor material, carbon nanoparticle (CNP), and P3HT, are developed and examined by inkjet-printing organic field-effect transistor technology in this work. The effective carrier mobility of fabricated OFETs can be enhanced by 8 folds with adding CNP and using O2plasma treatment. At the same time, the transconductance of fabricated OFETs is also raised by 5 folds. Based on the observations of SEM, XRD, and FTIR, these improvements are contributed to the local field induced by the formation of CNP/P3HT complexes. This observation presents an insight of the development in organic semiconductor materials. Moreover, this work also offers a low-cost and effective semiconductor material for inkjet-printing technology in the development of organic electronics.

Biomolecular patterning on a nanoscale/microscale on chip surfaces is one of the most important techniques used in vitro biochip technologies. Here, we report upon a stochastic mechanics model we have developed for biomolecular patterning controlled by surface potential. The probabilistic biomolecular surface adsorption behavior can be modeled by considering the potential difference between the binding and nonbinding states. To verify our model, we experimentally implemented a method of electroactivated biomolecular patterning technology and the resulting fluorescence intensity matched the prediction of the developed model quite well. Based on this result, we also experimentally demonstrated the creation of a bovine serum albumin pattern with a width of 200 nm in 5 min operations. This submicron noncovalent-binding biomolecular pattern can be maintained for hours after removing the applied electrical voltage. These stochastic understandings and experimental results not only prove the feasibility of submic...