Boosting Sensitivity and Reliability in Field‐Effect Transistor‐Based Biosensors with Nanoporous MoS₂ Encapsulated by Non‐Planar Al₂O₃

Abstract

Field‐effect transistors‐based biosensors (bio‐FETs) have been considered an important technology for label‐free and ultrasensitive point‐of‐care diagnostics. However, practical applications using bio‐FETs are limited due to the trade‐off between sensing reliability and sensitivity. This study suggests a reliable and sensitive bio‐FETs based on nanoporous molybdenum disulfide (MoS2) channels encapsulated by a non‐planar high‐k aluminum oxide (Al2O3) dielectric layer. Nanoporous MoS2 thin film is fabricated with an abundant edge area and periodically ordered nanopores via block copolymer lithography. The ultra‐thin Al2O3 dielectric layer deposited along the nanoporous structure of the MoS2 realizes effective electrostatic control of charged biomolecules over the MoS2 channel. In addition, it plays important roles in not only enhancing the electrical performance of the nanoporous MoS2 bio‐FETs, that is, mobility, hysteresis, and subthreshold swing, but also achieving effective biomolecular immobilization on the device surface. The nanoporous MoS2 channel structure surrounded by non‐planar Al2O3 detects a prostate cancer biomarker with an ultra‐low limit of detection of 1 fg mL−1. Moreover, the excellent selectivity, high sensitivity, and clinical reliability of the nanoporous MoS2 bio‐FETs are also confirmed. The proposed device platform provides new insights and technical advances in the field of FETs based sensors for future point‐of‐care devices.

Optical Enhancement of Indirect Bandgap 2D Transition Metal Dichalcogenides for Multi‐Functional Optoelectronic Sensors

“…The periodic hexagonal arrays of nanopores on the MoS 2 had abundant edge areas with a zigzag configuration of Mo and S atoms (Figure 2e). [54][55][56] The hexagonal edges with zigzag atomic configurations gave rise to multiple trap states in the bandgap, which was confirmed by photo-excited charge-collection spectroscopy measurements. The presence of trap states near the valance band assisted the PG effect under the illumination of light, which was confirmed by experiment and device simulation, respectively.…”

Nanoporous MoS2 Field-Effect Transistor Based Artificial Olfaction: Achieving Enhanced Volatile Organic Compound Detection Inspired by the Drosophila Olfactory System

“…The doublet of the Mo 3d signature positioned at 229.28 ± 0.07 eV (Mo 4+ 3d 5/2 ) and 232.43 ± 0.07 eV (Mo 4+ 3d 3/2 ) corresponds to stoichiometric MoS 2 , observed in both pristine and hexagonal nanoporous MoS 2 . Relatively smaller synthetic peaks positioned at 228.69 ± 0.17 eV (Mo 4+ 3d 5/2 ) and 231.84 ± 0.17 eV (Mo 4+ 3d 3/2 ) attributed to the nonstoichiometric MoS 2 (i.e., Mo x S y ) are present in both cases. , However, the atomic percentage and the peak intensity of nonstoichiometric MoS 2 significantly increased in the hexagonal nanoporous structure owing to the exposed edges and unsaturated bonds of hexagonal nanopores. The relative atomic fraction of nonstoichiometric MoS 2 is observed to be 4.38% in pristine MoS 2 , which is enhanced up to 44.07% in hexagonal nanoporous MoS 2 .…”

“…Resonators based on surface acoustic waves and bulk acoustic waves, integrated with OBPs, have been investigated for odorant detection in e-noses. − Additionally, e-nose sensors designed with human olfactory receptors with graphene and carbon nanotube (CNT) field-effect transistors (FETs) can emulate the natural olfactory mechanisms. − Other approaches, such as combining Drosophila OBPs with CNTs or silicon nanowires, have been explored. , However, the practical utilization of these materials faces challenges in terms of sensitivity, circuit integration, and mass production in large areas. Transition metal dichalcogenides (TMDs) possess several advantageous features over these materials, including large-area production and tunable electrical properties with high sensitivity and specific detection ability. − …”

Ultra‐Steep‐Slope and High‐Stability of CuInP2S6/WS2 Ferroelectric Negative Capacitor Transistors by Passivation Effect and Dual‐Gate Modulation

“…The shift of threshold voltage (V th ) towards negative V g can be attributed to the electron doping effect of Al 2 O 3 . [38,39] There exists a small hysteresis window of 0.15 and 0.3 V for both devices due to the ferroelectric polarization of CuInP 2 S 6 . For a pristine device, the transfer curve of the CuInP 2 S 6 /WS 2 -based Fe-NCFETs exhibits a counterclockwise direction, which is related to the ferroelectric polarization direction of the CuInP 2 S 6 layer.…”