In the past few decades, great attention has been paid to the development of IV–VI semiconductor colloidal quantum dots, such as PbSe, PbS and PbSSe, in infrared (IR) photodetectors due to their high photosensitivity, solution-processing and low cost fabrication. IR photodetectors based on field-effect transistors (FETs) showed high detectivity since the transconductance can magnify the drain–source current under certain applied gate voltages. However, traditional lateral FETs usually suffer from low photosensitivity and slow responsivity, which restricts their widespread commercial applications. In this work, therefore, novel vertical FET (VFET) based photodetectors are presented, in which the active layer is sandwiched between porous source electrode and planar drain electrode, resulting to ultrashort channel length. In this way, enhanced photoresponsivity and specific detectivity of 291 A W ⁻¹ and 1.84 × 10 ¹⁴ Jones, respectively, can be obtained at low drain–source voltage ( V _DS ) of −1 V and gate voltage ( V _g ) of −2 V under 100 μ W cm ⁻² illumination intensity, which was better than that of the traditional lateral FET based photodetectors. Therefore, it is promising to fabricate broadband photodetectors with high performance and good stability by this easy approach.

Recently, great attention has been paid to IV–VI colloidal quantum dots (CQDs) for their high photosensitivity, solution processability and low cost. Also, metal halide perovskites are very promising materials to realize the high-performance solution-processed visible-light photodetectors due to their cost-effective manufacturing, tunable absorption and photoluminescence in whole visible spectrum. In this paper, we present solution-processed CQDs-based tandem broadband photodetectors with low dark-current and high-sensitivity by inserting dielectric Polymethyl methacrylate (PMMA) interlayer between two sub-detectors. Our experimental data showed that the tandem broadband photodetector ITO/PEDOT:PSS/CsPbBr ₃ :PbS _0.4 Se _0.6 /ZnO/PVK/CsPbBr ₃ :PbS _0.4 Se _0.6 /ZnO/Au showed a maximum specific detectivity of 6.8 × 10 ¹³ Jones with a responsivity of 27 A W ⁻¹ under 57.8 μ W cm ⁻² 980 nm illumination. The device performance can be further enhanced by inserting a 50 nm dielectric PMMA layer between the two sub-photodetectors. As the result, the tandem photodetector ITO/PEDOT:PSS/CsPbBr ₃ :PbS _0.4 Se _0.6 /ZnO/PMMA(50 nm)/PVK/CsPbBr ₃ :PbS _0.4 Se _0.6 /ZnO/Au exhibits a maximum specific detectivity of 1.32 × 10 ¹⁴ Jones with a responsivity of 27.72 A W ⁻¹ under 57.8 μ W cm ⁻² of 980 nm laser. Further, the physical mechanisms for the enhanced performance are discussed in detail.

Implanted devices have important applications in biomedical monitoring, diagnosis and treatment, where intra-body communication (IBC) has a decent prospect in wireless implant communication technology by using the conductive properties of the human body to transmit a signal. Most of the investigations on implant IBC are focused on galvanic coupling type. Capacitive coupling IBC device seems hard to implant, because the ground electrode of it seemingly has to be exposed to air. Zhang et al. previously proposed an implantable capacitive coupling electrode, which can be totally implanted into the human body [1], but it lacks an overall characteristic investigation. In this paper, a comparable investigation of characteristics for implant intra-body communication based on galvanic and capacitive coupling is conducted. The human arm models are established by finite element method. Meanwhile, aiming to improve the accuracy of the model, electrode polarization impedance (EPI) is incorporated into the model, and the influences of electrode polarization impedance on simulation results are also analyzed. Subsequently, the corresponding measurements using porcine are conducted. We confirm good capacitive coupling communication performances can be achieved. Moreover, some important conclusions have been included by contrastive analysis, which can be used to optimize implant intra-body communication devices performance and provide some hints for practical IBC design. The conclusions also indicate that the implant IBC has promising prospect in healthcare and other related fields.

Implantable devices have important applications in biomedical sensor networks used for biomedical monitoring, diagnosis and treatment, etc. In this paper, an implant intra-body communication (IBC) method based on capacitive coupling has been proposed, and the modeling and characterization of this kind of IBC has been investigated. Firstly, the transfer function of the implant IBC based on capacitive coupling was derived. Secondly, the corresponding parameters of the transfer function are discussed. Finally, both measurements and simulations based on the proposed transfer function were carried out, while some important conclusions have been achieved, which indicate that the achieved transfer function and conclusions are able to help to achieve an implant communication method with the highly desirable characteristics of low power consumption, high data rate, high transmission quality, etc.

The method of Mach-Zehnder electro-optical modulation is applied to Intra-Body Communication (IBC), where the modeling and characterization of this type of IBC are discussed. The mathematical model of the electrostatic coupling IBC based on Mach-Zehnder electro-optical modulation is developed. The main characteristics of this IBC form have been simulated within the frequency range of 200 kHz-40MHz and compared to in-vivo measurements, with close agreements. Results show that the proposed method will help achieving good temperature characteristics, small size, and lower power consumption IBC system.

Simulation based on the finite-element (FE) method plays an important role in the investigation of intra-body communication (IBC). In this paper, a finite-element model of the whole body model used for the IBC simulation is proposed and verified, while the FE simulation of the galvanic coupling IBC with different signal transmission paths has been achieved. Firstly, a novel finite-element method for modeling the whole human body is proposed, and a FE model of the whole human body used for IBC simulation was developed. Secondly, the simulations of the galvanic coupling IBC with the different signal transmission paths were implemented. Finally, the feasibility of the proposed method was verified by using in vivo measurements within the frequency range of 10 kHz–5 MHz, whereby some important conclusions were deduced. Our results indicate that the proposed method will offer significant advantages in the investigation of the galvanic coupling intra-body communication.