We report an effective nonlinear readout body-coupled modulation strategy that enables electrical amplification of sensitivity in a single p-channel metal-oxide semiconductor (PMOS) field-effect transistor (FET). The threshold voltage exhibits a quadratic dependence on the body potential (VB) by dynamically biasing the body terminal instead of the gate, thus providing an extra electrical amplification from the intrinsic electrochemical surface potential changes. Implemented on a commercial PMOS with a TiN extended electrode here, this architecture achieves apparent VB-amplified sensitivity up to 1200 mV/pH, over twentyfold enhancement, without any additional circuit or process complexity. The p-channel configuration is crucial, as its less body-effect coupling and hole-dominated conduction enhance the interfacial response far beyond its n-type counterpart. The same body-coupled response also amplifies biomolecular recognition signals such as DNA hybridization, suggesting a transistor-level electrical amplification mechanism for chemical and biological sensing possibilities. This work introduces a minimalistic yet powerful approach that transforms conventional p-channel FETs into ultra-sensitive electrochemical transducers, establishing a scalable pathway toward high performance sensors. This is an ultra-low-cost route to achieving controllable high sensitivity, which offers an efficient amplification strategy over conventional approaches in field-effect sensors.

This study presents the combination of the electron transport layer (ETL) and insulating layers in the organic semiconductor-based light-addressable potentiometric sensor (LAPS) for consideration of stability and improvement over a lifetime. PFN-Br was chosen as the ETL to replace ZnO as a more uniform organic semiconductor coating with fewer defects and higher photoelectrical transfer efficiency. The mixture of PTB7-Th and PC71BM was spin coated for the organic semiconductor layer. A stacked sensing membrane comprised of Al2O3 and HfO2 was fabricated using atomic layer deposition (ALD) to improve the drift and hysteresis of a conventional single dielectric layer (e.g., pure Al2O3). Employing PFN-Br as ETL yielded improvements for maximum photocurrent of 24.35%, pH sensitivity of 2.35%, and hysteresis width of 9.24% compared to conventional ZnO. With the stacked sensing membrane, the drift coefficient was reduced by 22.4% and lasted for a 720-min measurement. The optimized organic semiconductor-based LAPS shows its feasibility with a sensitivity, linearity, drift coefficient, and hysteresis of 52.5 mV/pH, 99.9%, -2.53 mV/h, and -10.5 mV, respectively. These clear improvements mark a significant breakthrough for organic semiconductor-based LAPS into real pH sensing applications.

We present a novel organic semiconductor-based light-addressable potentiometric sensor (O-LAPS) system that employs a near-infrared (NIR) illumination of an 850 nm vertical-cavity surface-emitting laser (VCSEL), which could be tailored for cell-based biosensing applications. The use of NIR light offers several advantages in biological environment, including low phototoxicity, and minimal autofluorescence, enabling non-invasive, label-free monitoring of live-cell activity. This study introduces a new organic semiconductor device featuring a bulk heterojunction photoactive layer composed of PTB7-Th: PCBM: IEICO-4F, a low-bandgap organic blend optimized for NIR absorption. Under NIR excitation, the OLAPS demonstrates a pH sensitivity of $43.2 \text{mV} / \text{pH}$, confirming the capability of the device for field-effect chemical sensing. Additionally, the use of a VCSEL facilitates the miniaturization of the LAPS platform. These characteristics could refer to the potential of the NIR O-LAPS system for integration into longterm, flexible, cell-based sensors and point-of-care testing (POCT) applications in next-generation bioelectronic interfaces.

In recent years, owing to the demands of point-of-care tests (POCTs), sensors with the advantages of low cost, small dimensions, and precise detection have been widely developed. Extended-gate field-effect transistor (EGFET) devices stand out due to their simplified fabrication and excellent sensing performance. This study optimizes titanium nitride (TiN) sputtering as a gate material for a high-performance sensing membrane and integrates a custom-made quasi-reference electrode (C-qRE) onto the EGFET chip to develop a portable platform for detecting urinary tract stone-related biomarkers, including calcium ions (Ca2+) and urea. The optimized TiN membrane, fabricated under a nitrogen flow ratio of 60%, achieved a pH sensitivity of 59.4 mV/pH with linearity of 100%, and minimized drift (0.8 mV/h) and hysteresis (1 mV). Calcium ion detection showed 27.2 mV/pCa sensitivity with 99.9% linearity, while urea detection demonstrated 32.9 mV/mM sensitivity across 0.3-3.7 mM. The C-qRE maintained pH sensitivity of 57.2 mV/pH over 240 days. Furthermore, a multiplexed constant-voltage constant-current (CVCC) readout system was implemented to enable simultaneous measurement of multiple sensors, providing a compact and reliable alternative to conventional systems. This novel EGFET-based device integrates a semiconductor quasi-reference electrode (quasi-RE) for multimarker detection, offering high sensitivity, stability, and portability, and holds significant promise for clinical and home monitoring, representing a major advance in POCT diagnostics.

Controlling the morphology of dewetted ultrathin gold films is critical for achieving reproducible and high-performance plasmonic sensors, yet scalable approaches remain limited. Localized surface plasmon resonance (LSPR) sensors rely on uniform metallic nanoislands whose morphology dictates optical sensitivity and signal reproducibility. Conventional solid-state dewetting often produces non-uniform nanostructures due to uncontrolled interfacial energy and adatom mobility, restricting wafer-scale reproducibility. Here, a brief SF6 plasma pre-treatment is introduced that induces ion-mediated hydrophilic switching of glass surfaces, enhancing Au adatom mobility and promoting uniform nanoisland formation during thermal dewetting. The resulting structures exhibit reduced size dispersion and narrower interparticle gaps, yielding a 17.8% increase in refractive-index sensitivity (from 80.79 ± 19.36 to 95.21 ± 6.56 nm RIU-1) with improved linearity and spectral reproducibility. Complementing these experiments, a modified Cahn-Hilliard phase-field model embedding an explicit Au-substrate adhesion term (α) quantitatively reproduces the observed morphology and provides a predictive framework for tuning film evolution. This integrated experimental-theoretical-simulation approach demonstrates that substrate-wettability engineering via plasma activation offers a scalable, lithography-free strategy for wafer-level fabrication of uniform nanoplasmonic sensors, establishing a foundation for theory-informed design of next-generation plasmonic and photonic devices.

In this research, hafnium oxide (HfO2) was first fabricated in an in-house-developed high-power pulsed magnetron sputtering system (HiPIMS) functionalized for application as a high-performance extended gate field-effect transistor (EGFET) for the detection of pH and proteins associated with Parkinson's disease (PD). PD is the second most common neurodegenerative disease in elderly people after Alzheimer's disease. The α-synuclein protein in patients’ blood may be a potential biomarker in the early stage of PD. Detection of α-synuclein with high sensitivity and nonspecific binding through HfO2-EGFET biosensors has the advantages of low cost and simple fabrication from disposable EGs. Among the duty cycle conditions tested, HfO2 deposited at a 25% duty cycle in HiPIMS exhibited superior pH sensitivity and linearity, with values of 56.4mV/pH and 99.7%, respectively. The hysteresis width and drift coefficient are -3 mV and 0.3mV/h, respectively. To overcome the Debye length limitation, 100-fold diluted phosphate buffer solution and the PMOS configuration were used to determine the α-synuclein for which the isoelectric point was 4.67. The negative gate bias in the PMOS configuration successfully causes α-synuclein to approach the surface of HfO2 EG to achieve a sensitivity of 12.1mV/dec and a linearity of 99.5% in the range of 0.1 to 1000 pg/mL. The limit of detection is 0.198 pg/mL, and the immobilized surface ultimately binds specifically, resulting in low interference signals from other related biomarkers. This promising study shows that detecting various proteins involved in different diseases and performing clinical tests can be accomplished in the future.

To obtain a high-performance extended gate field-effect transistor for pH detection, hafnium nitride (HfN) was first fabricated on an indium tin oxide on polyethylene terephthalate (ITO/PET) substrate using a high-power impulse magnetron sputter system (HiPIMS) in this study. It can be easily applied in biomedical diagnostic and environmental monitoring applications with the advantages of flexible, disposable, cost-effective, and reliable components. Various duty cycle conditions in HiPIMSs were designed to investigate the corresponding sensing performance and material properties including surface morphology and composition. As the duty cycle increased, the grain size of HfN increased. Additionally, X-ray photoelectron spectroscopy (XPS) analysis illustrated the presence of HfOxNy on the deposited HfN surface. Both behaviors could result in a better pH sensing performance based on the theory of the site-binding model. Subsequently, HfN with a 15% duty cycle exhibited excellent pH sensitivity and linearity, with values of 59.3 mV/pH and 99.8%, respectively; its hysteresis width and drift coefficient were −1 mV and 0.5 mV/h, respectively. Furthermore, this pH-sensing performance remained stable even after 2000 repeated bending cycles. These results indicate the potential and feasibility of this HiPIMS-deposited HfN for future wearable chemical applications.

Mo-doped VO2 thin-films are deposited on the soda-lime glass by a reactive high-power impulse magnetron co-sputtering technique (R-HiPIMS). Rapid thermal annealing at 500 degrees C for 3 min is performed to achieve the fabrication under low thermal budget. To prevent VO2 from further oxidation, a conformal and semi-conducting MoOx film is applied as the capping layer by the plasma-enhanced atomic layer deposition (PE-ALD). After MoOx film is deposited, an electrical transition in the resistance ratio of 6-10 orders of magnitude has been found, especially for MoOx thicknesses less than 20 nm. A secondary phase of V2O3 plays an important role in abrupt change of current transportation. Also, the hysteresis of optical transition in transmittance at a wavelength of 2500 nm shows that both the width and transition temperature (T-C) decrease with increasing the thickness of the MoOx cap. Moreover, the effect of localized surface plasmonic resonance (LSPR) due to the Karst-like structure has been detected by the absorption spectrum. The variations in LSPR peak, such as intensity, blue-shifting, and red-shifting, originated from either excess carrier or structure change are discussed. The high aspect ratio of surface morphology is further examined by atomic force microscopy. In addition, the coverage of MoOx on Mo-doped VO2 concerning the friction behavior is evaluated by lateral force microscopy (LFM), which is helpful in clarifying the responsible mechanisms during T-C transition.

The fabrication of p-type tin monoxide (SnO) thin films at room temperature poses significant challenges for conventional methods, primarily due to the electrically anisotropic nature and metastable phases of SnO. Because of this anisotropy, generating effective hole carriers with optimal mobility in SnO requires meticulous thermal annealing, which is nonetheless constrained by SnO's metastability. In this work, we employ ion-beam-assisted deposition (IBAD) to fabricate p-type SnO thin films at room temperature. These films, with their nanocrystalline structure, demonstrate promising electrical performance with a Hall mobility of 2.67 cm2 V-1 s-1 and hole concentration of 5.94 x 1017 cm-3, notably without the need for annealing treatment. Our investigation has revealed a unique volcano-shaped trend in Hall mobility, and inversely, in carrier concentration in response to variations in the argon flow rate during the IBAD process. This relationship, when correlated with changes in the optical properties, structural phase, and chemical state of the films, is crucial for understanding the origin of p-type conductivity in room-temperature-fabricated SnO films-a topic that remains elusive in the current literature. We observed a direct correlation between enhanced mobility and reduced lattice disorder, as well as a strong association between increasing hole carrier concentration and the formation of oxygen interstitials. We also highlight that the intermediate phase composition plays a vital role in determining the degree of disorder in the SnO film, which is essential for creating transport pathways and the oxygen environment necessary for hole carrier formation. These insights are instrumental in guiding the design and characterization of room-temperature fabricated p-type SnO thin films, thus propelling advancements in the field of large-area, flexible electronics. This study showcases the use of ion-beam-assisted deposition for fabricating p-type SnO thin films at room temperature, which reveals crucial links between Hall mobility and lattice disorder, and between hole concentration and the relative content of interstitial oxygen.

Localized Surface Plasmon Resonance (LSPR) stands out as a powerful sensing method, where nanostructures can be formed by depositing a thin layer of metal onto a substrate followed by Rapid Thermal Annealing (RTA). This study investigates the influence of annealing temperature on the morphology, optical properties, and sensitivity of gold nanostructures fabricated on glass substrates. Utilizing thermal annealing, gold thin films were treated at temperatures ranging from 550 degrees C to 850 degrees C to create distinct nanostructures, which were evaluated using scanning electron microscopy (SEM) and extinction spectra measurements. The analysis revealed a significant impact of annealing temperature on the LSPR characteristics, including a blue shift in the LSPR peak and changes in the full width at half maximum (FWHM) as nanostructure uniformity improved. Finally, we conducted measurements on different chips using glycerol-water solutions of various concentrations, observing that the sensitivity decreased with the annealing temperature. This research offers critical insights into the enhancement of LSPR-based sensors through precise manipulation of nanostructure formation, highlighting the pivotal role of temperature control.

Localized surface plasmon resonance (LSPR) in plasmonic nanoparticles propels the field of plasmo-electronics, holding promise for transformative optoelectronic devices through efficient light-to-current conversion. Plasmonic excitations strongly influence the charge distribution within nanoparticles, giving rise to electromagnetic fields that can significantly impact the macroscopic charge flows within the nanoparticle housing material. In this study, we present evidence of ultralow, unconventional breathing currents resulting from dynamic irradiance interactions between widely separated nanoparticles, extending far beyond conventional electron (quantum) tunneling distances. We develop an electric analogue model and derive an empirical expression to elucidate the generation of these unconventional breathing currents in cascaded nanoplasmonic systems under irradiance modulation. This technique and theoretical model have significant potential for applications requiring a deeper understanding of current dynamics, particularly on large nanostructured surfaces relevant to photocatalysis, energy harvesting, sensing, imaging, and the development of future photonic devices.

Lead (Pb) ion detection poses a critical problem, particularly in environmental monitoring, industrial operations, and public health, especially for young children and expecting women. Determining lead levels in blood early on is essential to minimizing the long-term consequences of lead exposure. Several sophisticated detection instruments, such as mass spectrometers which perform with high sensitivity, specificity and accuracy, but require a lab-based setting, multi-step sample preparation, expensive payment and professional operation. It is evident that a highly sensitive, portable, low-cost, quick sample-to-result, blood lead detection device that can be tested at the point-of-care is necessary. Consequently, we developed a unique ZnO/PEDOT:PSS nanocomposite layer integrated with a CMOS MEMS-based bridge-like membrane-type (BM) nanomechanical sensor for detecting lead levels in blood. PEDOT:PSS was combined with ZnO nanorods to increase lead ion binding. The sensor responds seven times better to lead ions using nanorods in the detecting layer. A linear resistance change rate response was found from 0.005 to 10 ppm, with the limit of detection (LOD) of 0.12 ppb. Similarly, our BM nanomechanical sensor can correctly assess Pb2+ in human serum with recovery rates of 86.25-150 %. Measurements of human blood samples from patients with varying lead ion concentrations validated by the standard AAS show a good linear connection with the BM nanomechanical sensors' concentration, with a regression coefficient of 0.92. This describes the first micromachined nanoachanical sensing system for detection of Pb2+ in only 5 μL of human serum sample. The device achieves a time-to-result of less than 10 min. The system is designed to be very sensitive and offers affordable, disposable sensing chips together with a portable signal acquisition platform.

Methodology of electrical characterization of ISFETs has been described. It is based on a three-stage approach. First, electrical measurements of ISFET-like MOSFETs and extraction of basic parameters of the MOSFET compact model are performed. Next, mapping of the ISFET channel conductances and a number of other characteristic parameters is carried out using a semi-automatic testing setup. Finally, ISFET sensitivity to solution pH is evaluated. The methodology is applied to characterize ISFETs fabricated in the Institute of Electron Technology (IET).

This study aims to develop a refractive-index sensor operating in the visible region using an all-dielectric metasurface, which was chosen for its advantages of low optical loss and narrow spectral bandwidth, compared to those of conventional metallic metasurfaces. COMSOL software was utilized as a calculation tool to simulate the resonant properties of an all-dielectric metasurface composed of a circular nanohole-structured titanium oxide (TiO2) thin film, with the aim of enhancing the sensitivity of the refractive index for sensing targets. The simulation focused on finding the best geometrical conditions for the all-dielectric metasurface to achieve high sensitivity. Two resonance modes observed in this metasurface were considered: the quasi-bound-state-in-the-continuum (qBIC) mode and the perfect-reflection (PR) mode. The simulated results demonstrated that high sensitivities of 257 nm/RIU at the PR mode and 94 nm/RIU at the qBIC mode in the visible spectral range could be obtained by periodically constructing the metasurface with a unit cell having a lattice constant of 350 nm, a nanohole radius of 160 nm, and a nanohole depth of 250 nm. Furthermore, the study showed that the resonance mode that enabled high sensitivity was the PR mode, with a sensitivity nearly three times larger than that of the qBIC mode and the ability to reach the highest reflectance at the resonance wavelength. The optimized feature had the highest reflectance at a resonant wavelength of 570.19 nm, and although the quality factor was 25.50, these designed parameters were considered sufficient for developing a refractive index biosensor with high sensitivity and optical efficiency when operating in the visible spectral range.

The debye length is a measure of the distance over which the electric field of a charged particle decays in an electrolyte solution. If the binding of the analyte to the surface of the transducer is too far away from the surface, the electric field to the analyte may decay over a distance greater than the debye length thereby reducing the sensitivity of the measurement. In this context, this study has developed a simple one‐step protein immobilization strategy to covalently attach proteins on the sensor surface. Our binding strategy, which uses hydrogen peroxide (H 2 O 2 ) ensures that the analyte is attached as close as possible to the transducer surface. This study evaluates our findings by comparing our strategy with silane chemistry and elucidating the debye length effects with colorimetric assays and field effect devices. Additionally, as a case study, we also evaluated the performance of our methodology for the detection of glucose oxidation by a field effect device. Overall, the developed immobilization strategy avoids the effects of the debye length and improves the performance of the biosensor.

Size-based sorting and separation of microparticles is critical for many applications. Conventional techniques might not be suitable for this task particularly when sample is limited. Integration of optically induced dielectrophoresis (ODEP) in microfluidic system for the task is believed promising. However, its utilization can be limited by the influence of the friction force acting on microparticles. In this situation, the microparticles might not be effectively sorted and separated. To address this challenge, this study presented an ODEP-based virtual gel filtration chromatography (GFC)-inspired mechanism. By mimicking the concept of GFC, this study proposed to use a circular light image array to maximize the retention time difference among various microparticles when they flowed through such an array. In this study, the array design and its operational conditions were determined. Additionally, its performance for sorting and separation of polystyrene (PS) microbeads with 4 different sizes was evaluated. Results demonstrated that the proposed method was capable of sorting and separating microbeads in a high-performance manner (e.g., purity range: 92–100%). This could be beyond what is currently possible using the current ODEP-based method. Overall, this study presented a new ODEP technique that could solve the problems commonly encountered in ODEP-based microparticle sorting, and separation.

In this study, the first trial of donor and acceptor bulk heterojunctions (BHJs) is proposed for light-addressable potentiometric sensors (LAPSs) due to organic conjugated molecules with the advantages of energy level/band gap modification and high absorption of visible light. The benzodithiophene-based polymer PTB7-Th and fullerene PC71BM are selected for integration with an Al2O3 sensing membrane using atomic layer deposition at temperatures lower than 100 celcius for pH sensing LAPS. In the stability performance, the hysteresis width of the best condition with a mixing weight ratio of PC71BM to PTB7-Th of 1.5 is 4.4 mV, which is inferior to that of the conventional inorganic semiconductor-based LAPSs. By means of an additional spin-coated zinc oxide (ZnO) layer, the signal-to-noise ratio of the photocurrent of this fabricated LAPS can be maintained at 3.2 after 170 min of measurement with an acceptable sensitivity, linearity, drift coefficient and hysteresis of 50.2 mV/pH, 99.9%, - 3.1 mV/h and 1.4 mV, respectively. With the proper adjustment of illumination with low power and large spots, chemical imaging with a scanning step of 25 mu m can be conducted to indicate the feasibility of this lowtemperature process developed for spin-coated organic semiconductor-based LAPSs.

For the rapid detection of bacteria in a blood sample, nucleic acid amplification-based assays are believed to be promising. Nevertheless, the nucleic acids released from the dead blood cells or bacteria could affect the assay performance. This highlights the importance of the isolation of live bacteria from blood samples. To address this issue, this study proposes a two-step process. First, a blood sample was treated with the immuno-magnetic microbeads-based separation to remove the majority of blood cells. Second, an optically induced dielectrophoresis (ODEP) microfluidic system with an integrated dynamic circular light image array was utilized to further isolate and purify the live bacteria from the remaining blood cells based on their size difference. In this work, the ODEP microfluidic system was developed. Its performance for the isolation and purification of bacteria was evaluated. The results revealed that the method was able to harvest the live bacteria in a high purity (90.5~99.2%) manner. Overall, the proposed method was proven to be capable of isolating and purifying high-purity live bacteria without causing damage to the co-existing cells. This technical feature was found to be valuable for the subsequent nucleic-acid-based bacteria detection, in which the interferences caused by the nontarget nucleic acids could be eliminated.