Search

This paper presents an ultra-high-frequency (UHF) passive sense tag for electrical grid and substation thermal monitoring, with emphasis on the tag system optimization and the design of a low power embedded temperature sensor. The designed tag achieves a sensitivity of $-$ 12.3 dBm under active temperature monitoring operation, which is the state of the art among existing UHF passive temperature sense tag products. The sensing inaccuracy of the tag is $\pm$ 2.5 $^{\circ }$ C (3 $\sigma$) from $-$ 25 to 120 $^{\circ }$ C after a low-cost wireless single-point trim. An antimetal ceramic-packaged tag was tested by attaching to a ring main unit in the substation and complete tag system demonstrated robust wireless operation with a sensing distance of 3.5 m. The combination of batteryless and wireless operation, high sensitivity, wide sensing range, and small incident-power-dependent error ($\pm$ 0.2 $^{\circ }$ C) makes this tag suitable for the target applications. [ABSTRACT FROM AUTHOR]

This brief reports a small size single-photon avalanche diode (SPAD) in baseline 65-nm CMOS suitable for low-cost time-of-flight application with high spatial resolution. By exploiting the less-doped n-well region to surround the vertical p-well/deep-n-well multiplication region, the electric field at the SPAD periphery can be reduced without process modifications while avoiding premature lateral breakdown. Validated using TCAD simulations, the fabricated 4-μm diameter SPAD device exhibits a compact device size with a low dark count (73 cps/μm2 at 20 °C) and a high fill factor (17.7%) using 65-nm baseline CMOS, while demonstrating competitive performance when compared with the state of the art. [ABSTRACT FROM AUTHOR]

This paper reports a global digital controller for multi-channel high density micro-stimulator applications. By centralizing the essential functions including stimulation timing controls, tissue-electrode impedance (TEI) monitoring and power supply modulation in the global digital controller (GDC), digital blocks in the local electrode driver channels (LEDCs) can be greatly simplified, resulting in compact electrode drivers suitable for high density intracellular stimulations. Based on the proposed column-parallel row-scanning (CPRS) stimulator topology, the 5-wire global control ensures customized per channel stimulation with minimal interfacing overhead. A 4-column GDC stimulator prototype is fabricated in a 0.18 µm CMOS process. It features flexible stimulation with a power consumption of 18 µW/column while enabling global power-supply modulation and real-time TEI monitoring for improved stimulation efficiency and safety. [ABSTRACT FROM AUTHOR]

In this paper, a wide input range supply voltage tolerant capacitive sensor readout circuit using on-chip solar cell is presented. Based on capacitance controlled oscillators (CCOs) for ultra-low voltage/power consumption, the sensor readout circuit is directly powered by the on-chip solar cell to improve the overall system energy efficiency. An extended sensing range with high sensing accuracy is achieved using a two-step successive approximation register (SAR) and delta-sigma () analog-to-digital (A/D) conversion (ADC) scheme. Digital controls are generated on-chip using a customized sub-threshold digital standard cell library. Systematic error analysis and optimization including the finite switch on-resistance, buffer input-dependent delay, and SAR quantization nonlinearity are also outlined. High power supply rejection ratio (PSRR) is ensured by using a pseudo-differential topology with ratiometric readout. The complete sensing system is implemented using a standard 0.18m complementary metal-oxide-semiconductor (CMOS) process. Simulation results show that the readout circuit achieves a wide input range from 1.5pF to 6.5pF with a worst case PSRR of 0.5% from 0.3V to 0.42V (0.67% from 0.3V to 0.6V). With a 3.5pF input capacitance and a 0.3V supply, the stage achieves a resolution of 7.1-bit (corresponding to a capacitance of 2.2fF/LSB) with a conversion frequency of 371Hz. With an average power consumption of 40nW and a sampling frequency of 47.5kHz, a figure-of-merit (FoM) of 0.78pJ/conv-step is achieved. [ABSTRACT FROM AUTHOR]

A compact voltage-mode bandgap voltage reference (BGR) is presented. Instead of using overhead circuits, the silicon bandgap narrowing effect is exploited for bipolar junction transistor’s (BJT) curvature reduction and residual curvature correction. Prototype measurements in a 0.18- \mu \textm standard CMOS process show that the curvature of the BJT is effectively reduced from its inherent 3.6 mV to 1.4 mV. The proposed BGR measures a minimum temperature coefficient of 8.7 ppm/ °C from −55 °C to 125 °C by batch trimming one resistor. After a curvature trimming, it further improves to 4.1 ppm/ °C. The BGR has a minimum supply voltage of 1.3 V, 4.3 \mu \textA nominal current consumption, 0.03%/V line sensitivity, and 2 mV/mA load sensitivity at 25 °. The output rms noise in the $0.1\sim 10$ -Hz band measures 10.23 \mu \text{V} . [ABSTRACT FROM PUBLISHER]

Single-nucleotide polymorphism (SNP) plays a critical role in personalized medicine, forensics, pharmacogenetics, and disease diagnostics. Among different existing SNP genotyping techniques, melting curve analysis (MCA) becomes increasingly popular due to its high accuracy and straightforward procedures in extracting the melting temperature (Tm). Yet, its study on existing digital microfluidic (DMF) platforms has intrinsic limitations due to the temperature inhomogeneity within a thickened droplet during the on-chip rapid heating process. Although the utilization of an on-chip thermostat can regulate and monitor the dynamic melting process in real time, the limited Tm accuracy resulting from the insufficient system response time to accommodate the fast-melting evolution still poses a great challenge for precise MCA with high throughput. This work proposes a one-shot MCA on a DMF platform. The tailoring of a functional substrate with hierarchical micro/nano structure enables high-resolution patterning of pL-scale droplets. Specifically, the hydrothermal and photocatalysis treatment allows the functional substrate to exhibit a superwettability contrast of >170°, facilitating passive isolation of the pL-scale DNA sample into highly-resolved pL droplets above the 200 μm superhydrophilic patterns. This high-resolution MCA technique can successfully discriminate KRAS gene targets with single-nucleotide mutations in 3 seconds. The high accuracy and consistency in the acquired Tm when compared with off-chip results demonstrate its opportunities for near-patient diagnostics, precision medicines, genetic counseling, and prevention strategies on DMF platforms. [ABSTRACT FROM AUTHOR]

The development of a rapid and reliable polymerase chain reaction (PCR) method for point-of-care (POC) diagnosis is crucial for the timely identification of pathogens. Microfluidics, which involves the manipulation of small volumes of fluidic samples, has been shown to be an ideal approach for POC analysis. Among the various microfluidic platforms available, digital microfluidics (DMF) offers high degree of configurability in manipulating μL/nL-scale liquid and achieving automation. However, the successful implementation of ultrafast PCR on DMF platforms presents challenges due to inherent system instability. In this study, we developed a robust and ultrafast PCR in 3.7–5 min with a detection sensitivity comparable to conventional PCR. Specifically, the implementation of the pincer heating scheme homogenises the temperature within a drop. The utilization of a μm-scale porous hydrophobic membrane suppresses the formation of bubbles under high temperatures. The design of a groove around the high-temperature zone effectively mitigates the temperature interference. The integration of a soluble sensor into the droplets provides an accurate and instant in-drop temperature sensing. We envision that the fast, robust, sensitive, and automatic DMF system will empower the POC testing for infectious diseases. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Ni-doped Bi 2 O 2 CO 3 nanosheet is prepared as insertion-type anode of "rocking chair" AZIBs. • The cross-linked CNTs conductive network improves the electronic conductivity and structure stability of electrode. • The Ni doping enhances the electronic/ionic transmission and electrochemcial reversibility of Bi 2 O 2 CO 3. • The H+/Zn2+ co-insertion mechanism of Bi 2 O 2 CO 3 is proved via ex situ XRD and XPS. • Ni-Bi 2 O 2 CO 3 //MnO 2 "rocking chair" AZIBs exhibit high reversible capacity. Developing insertion-type anode is key to advancing "rocking chair" zinc-ion batteries, though there are few reported insertion-type anodes. Herein, the Bi 2 O 2 CO 3 is a high-potential anode, with a special layered structure. A one-step hydrothermal method was used to prepare Ni-doped Bi 2 O 2 CO 3 nanosheet, and also a free-standing electrode consisting of Ni-Bi 2 O 2 CO 3 and CNTs was designed. Both cross-linked CNTs conductive networks and Ni doping improve charge transfer. Ex situ tests (XRD, XPS, TEM, etc.) reveal the H+/Zn2+ co-insertion mechanism of Bi 2 O 2 CO 3 and that Ni doping improves its electrochemical reversibility and structural stability. Therefore, this optimized electrode offers a high specific capacity of 159 mAh g−1 at 100 mA g−1, a suitable average discharge voltage of ≈0.400 V, and a long-term cycling stability of 2200 cycles at 700 mA g−1. Besides, the Ni-Bi 2 O 2 CO 3 //MnO 2 "rocking chair" zinc-ion battery (based on the total mass of cathode and anode) delivers a high capacity of ≈100 mAh g−1 at 50.0 mA g−1. This work provides a reference for designing high-performance anode in zinc-ion batteries. [ABSTRACT FROM AUTHOR]

Highlights • Achieving the reference hybridization equilibrium with >13 times faster reaction rate. • Rapid mixing with wide range of DNA concentrations (from 1 to 10 μM). • On-chip isothermal DNA hybridization within ±0.1°C. Abstract DNA hybridization kinetics has been playing a critical role in molecular diagnostics for binding discrimination, but its study on digital microfluidic (DMF) systems is ultimately restrained by the laminar flow condition. The kinetic mixing technique is widely employed to ensure a fast reaction rate, but poses intrinsic risk in cross contamination and exhibits instable fluorescence intensity during the droplet transportation. While the electrothermal technique can provide stationary droplet mixing through the established thermal gradient within the hybridization solution, the significant increase in the droplet temperature will inevitably undermine the hybridization equilibrium and jeopardize the binding discrimination. To enhance the hybridization efficiency while ensuring a stable droplet temperature (within ±0.1℃), this paper presents a DMF platform that can perform isothermal hydrodynamic-flow-enhanced droplet mixing. Specifically, with a single electrode, droplet-boundary oscillation under a slow AC actuation is studied for improving the reaction rate. The dependencies between the mixing efficiency and the actuation voltage, actuation frequency and the spacer thickness are also systematically studied. Reliable mixing efficiency improvement is further validated over a wide range of solute concentrations. The results from real-time on-chip DNA hybridization kinetics with stationary droplets using the complete sandwiched DMF system shows that the proposed rapid mixer can achieve the same hybridization equilibrium with >13 times faster reaction rate when compared to the reference one through pure diffusion, while preventing biased hybridization kinetics as demonstrated in the electrothermal technique. [ABSTRACT FROM AUTHOR]

Complementary metal oxide semiconductor (CMOS) technology enables low-cost and large-scale integration of transistors and physical sensing materials on tiny chips (e.g., ＜1 cm2), seamlessly combining the two key functions of biosensors: transducing and signal processing. Recent CMOS biosensors unified different transducing mechanisms (impedance, fluorescence, and nuclear spin) and readout electronics have demonstrated competitive sensitivity for in vitro diagnosis, such as detection of DNA (down to 10 aM), protein (down to 10 fM), or bacteria/cells (single cell). Herein, we detail the recent advances in CMOS biosensors, centering on their key principles, requisites, and applications. Together, these may contribute to the advancement of our healthcare system, which should be decentralized by broadly utilizing point-of-care diagnostic tools. [ABSTRACT FROM AUTHOR]

A bipolar junction transistor (BJT)‐based CMOS temperature sensor exploiting the piecewise BJT process spread compensation property of the base recombination current is proposed to reduce the process variations of the base–emitter voltage (Vbe). The weighted combinations of different on‐chip resistors are explored to minimise their associated process spread. Fabricated in standard 0.18‐μm CMOS, the chip prototype occupies an active area of 0.036 mm2 and draws 3 μA from a 1.2 V supply, with a measured maximum inter‐/intra‐die variation in Vbe of <1.5 mV from −40 to 125°C from two batches. Using the measured Vbe, ΔVbe and the first‐batch‐only calibration parameters, the chip prototype demonstrates an untrimmed batch‐to‐batch inaccuracy of ± 1.5°C (3σ) within the same temperature range (24 samples from 2 batches). [ABSTRACT FROM AUTHOR]

This letter presents an automatic power‐stage implementation and optimization methodology for fully‐integrated reconfigurable switched‐capacitor (SC) DC‐DC converters with fine‐grained voltage conversion ratios (VCRs). The proposed technique resolves the design challenge of a simultaneous realization of full capacitance utilization, optimal sub‐cell sizing ratio, and implementation complexity reduction. It is based on the proposed partitioning algorithms and attains a significant sub‐cell number reduction, particularly for finer‐grained VCR designs, saving the power‐stage area overhead. With a given set of VCRs and hardware constraints, the proposed methodology can generate a specific power‐stage partitioning solution, including the total number and sizing ratio for the power stage sub‐cells, ensuring an optimal power‐stage conduction loss property under a given on‐chip capacitance area. The proposed methodology is applicable to both linear and binary types of SC converters. Compared with the advanced works, the proposed method realizes the number of sub‐capacitors reduction over 50% under the same VCRs. Meanwhile, over 90% of the sub‐cells can be eliminated for linear‐type SC converters with a VCR range of 10:1–2:1, theoretically. [ABSTRACT FROM AUTHOR]

This letter presents two transient enhancement techniques for multi‐path switched‐capacitor‐inductor (MP‐SCI) hybrid DC–DC converters to eliminate the line‐transient‐induced voltage coupling to the converter output. Since the existing input‐feedforward method is hard to apply to the MP‐SCI converter, the proposed techniques tackle the intrinsic hard‐charging property with the MP‐SCI topology, preventing the line‐coupling current through topology operation reconfiguration and power‐switch modulation. The proposed controller also achieves adaptive line‐transition detection and automatic flying‐capacitor voltage balancing, ensuring a fast line regulation feature. Implemented with an MP‐SCI topology for a 9 to 14 V‐input to 5 V‐output conversion, the proposed control techniques provide an output (VOUT) overshoot and undershoot as low as 0.5% of the output DC level under a 3‐V input voltage step. From the simulation, the corresponding output variation reduction can be more than 94% when compared with the existing MP‐SCI operations. Besides, the proposed controller is compatible with a voltage‐mode (VM) V2 pulse‐width modulation (PWM) function, achieving a fast load‐transient recovery in six switching cycles and a VOUT variation of 75 mV at a 5 V DC level under a 0‐to‐3 A load step. The peak conversion efficiency can be as high as 95.5%, and the targeted load current delivery is up to 3 A. [ABSTRACT FROM AUTHOR]

Herein, we describe a micro-nuclear magnetic resonance (μNMR) relaxometer miniaturized to palm-size and electronically automated for multi-step and multi-sample chemical/biological diagnosis. The co-integration of microfluidic and microelectronic technologies enables an association between the droplet managements and μNMR assays inside a portable sub-Tesla magnet (1.2 kg, 0.46 Tesla). Targets in unprocessed biological samples, captured by specific probe-decorated magnetic nanoparticles (NPs), can be sequentially quantified by their spin–spin relaxation time (T2) via multiplexed μNMR screening. Distinct droplet samples are operated by a digital microfluidic device that electronically manages the electrowetting-on-dielectric effects over an electrode array. Each electrode (3.5 × 3.5 mm2) is scanned with capacitive sensing to locate the distinct droplet samples in real time. A cross-domain-optimized butterfly-coil-input semiconductor transceiver transduces between magnetic and electrical signals to/from a sub-10 μL droplet sample for high-sensitivity μNMR screening. A temperature logger senses the ambient temperature (0 to 40 °C) and a backend processor calibrates the working frequency for the transmitter to precisely excite the protons. In our experiments, the μNMR relaxometer quantifies avidin using biotinylated Iron NPs (Φ: 30 nm, [Fe]: 0.5 mM) with a sensitivity of 0.2 μM. Auto-handling and identification of two targets (avidin and water) are demonstrated and completed within 2.2 min. This μNMR relaxometer holds promise for combinatorial chemical/biological diagnostic protocols using closed-loop electronic automation. [ABSTRACT FROM AUTHOR]

We present a modular nuclear magnetic resonance–digital microfluidics (NMR–DMF) system as a portable diagnostic platform for miniaturized biological assays. With increasing number of combinations between designed probes and a specific target, NMR has become an accurate and rapid assay tool, which is capable of detecting particular kinds of proteins, DNAs, bacteria and cells with a customized probe quantitatively. Traditional sample operation (e.g., manipulation and mixing) relied heavily on human efforts. We herein propose a modular NMR–DMF system to allow the electronic automation of multi-step reaction-screening protocols. A figure-8 shaped coil is proposed to enlarge the usable inner space of a portable magnet by 4.16 times, generating a radio frequency (RF) excitation field in the planar direction. By electronically managing the electro-wetting-on-dielectric (EWOD) effects over an electrode array, preloaded droplets with the inclusion of biological constituents and targets can be programmed to mix and be guided to the detection site (3.5 × 3.5 mm2) for high-sensitivity NMR screening (static B field: 0.46 T, RF field: 1.43 mT per ampere), with the result (voltage signal) displayed in real-time. To show the system's utility, automated real-time identification of 100 pM of avidin in a 14 μL droplet was achieved. The system shows promise as a robust and portable diagnostic device for a wide variety of biological analyses and screening applications. [ABSTRACT FROM AUTHOR]

Digital microfluidics (DMF) shows great potential in the manipulation of individual droplets. However, the limited number of electrode control wirings for droplet control intrinsically restrains the massive generation of pL/nL individual droplets, fundamentally hindering the realization of high throughput applications on DMF such as digital nucleic acid amplification and analysis. This work demonstrates on-chip high throughput digital loop-mediated isothermal amplification (dLAMP) on a DMF platform based on a functional substrate with super-wettability contrast. Exploiting the passive dispensing technique as empowered by electrowetting on dielectric (EWOD) effect, a total of 1818 individual droplets with high uniformity are generated on the super-hydrophilic microarray within 1 min. Separation within the oil phase without tubes and valves can avoid evaporation, ensuring a precise total reaction volume. Absolute quantification of λDNA with a dynamic range of 1–1000 copies/μL is achieved by counting the amount of positive microdroplets after on-chip incubation, demonstrating the strong potential for rapid, low-cost, reliable, and quantitative nucleic acid analysis with high accuracy. • High-throughput digital microfluidics platform. • High uniformity among microdroplets. • No dead volume for ensuring a precise total reaction volume. • On-chip high precision absolute quantification of nucleic acid. [ABSTRACT FROM AUTHOR]

A three‐stage amplifier employing embedded capacitor‐multiplier compensation (ECMC) and active parallel compensation (APC) to enhance the area efficiency when driving nF‐range capacitive loads (CL) is presented. Unlike the conventional current‐buffer Miller compensation, ECMC applied to the dominant compensation path saves substantial power and area, while securing a large gain–bandwidth product. The created left‐half‐plane zero also benefits the phase margin (PM). For the APC, unlike the traditional passive parallel compensation, this work benefits from the Miller effect to avoid the area‐consuming resistor, and reduces the entailed capacitances without lowering the parasitic pole position. A multi‐path Gm‐boosting second stage enhances the effective transconductance and DC gain. With 0.0045 mm2 of area and 15.8 µW of power, the 0.18 µm CMOS three‐stage amplifier measures 1.13 MHz unity‐gain frequency, 0.41 V/µs average slew rate and 56.2° PM at 1 nF CL. Stable responses with >50° PM are attained for a 10 × range of CL from 0.15 to 1.5 nF. The achieved figure‐of‐merit accounting for both die area and power compares favourably with the state of the art. [ABSTRACT FROM AUTHOR]

SUMMARY: The Internet of Everything (IoE), clearly a 21st century's technology, brilliantly plays with digital data obtained from analog sources, bringing together two different realities, the analog (physical/real), and the digital (cyber/virtual) worlds. Then, with the boundaries of IoE still analog in nature, the required functions at the interface involve sensing, measuring, filtering, converting, processing, and connecting, which imply that the analog layer governs the entire system in terms of accuracy and precision. Furthermore, such interface integrates several analog and mixed‐signal subsystems that comprise mainly signal transmission and reception, frequency generation, energy harvesting, data, and power conversion. This paper sets forth a state‐of‐the‐art design perspective of some of the most critical building blocks used in the analog/digital interface, covering wireless cellular transceivers, millimeter‐wave frequency generators, energy harvesting interfaces, plus, data and power converters, that exhibit high quality performance achieved through low‐power consumption, high energy‐efficiency, and high speed. [ABSTRACT FROM AUTHOR]

This paper proposes a precision bandgap voltage reference (BGR) with a segmented curvature compensation technique, demonstrating both small temperature coefficient (TC) and low power consumption. By segmenting the output voltage of a conventional first-order BGR over a wide temperature range and implementing compensation for each segment, the output reference voltage can be systematically aligned to an identical voltage level, effectively reducing the achievable TC. An additional circuit consists of comparators, logic gates, switches and current mirrors is proposed to achieve this compensation scheme, which also optimizes the overall BGR power consumption. Implemented and simulated in a standard 65 ​nm CMOS process, the proposed BGR achieves an average output of 496.17 ​mV and a TC of 1.08 ​ppm/°C from −40 ​°C to 125 ​°C. It consumes a current of 765 ​nA under a 1.2 ​V supply while exhibiting a line regulation of 0.725%/V with V DD from 1.0 to 1.8 ​V ​at 27 ​°C. [ABSTRACT FROM AUTHOR]

Swift and convenient handling of discrete micro-droplets on digital microfluidics platform has recently attracted plentiful interest in high-throughput bio/chemical analysis. In this work, we developed a novel and facile approach to manipulate the micro-droplet based on a hydrophobic and low-adhesive magnetically functionalized polydimethylsiloxane (MF-PDMS) membrane. The platform is composed of the MF-PDMS membrane as the substrate, integrated with non-magnetic PDMS micro-pillar arrays on-top to ensure the low adhesion between the platform and the resident drops. With applied magnetic field, the localized membrane deformation could induce the unbalanced force imposed on the micro-droplet, leading to free rolling-off for flexible control including the position and velocity, etc. We have experimentally verified that the proposed avenue could be successfully applied for kinds of on-chip micro-droplet manipulations, such as droplet merging, parallel manipulation, flexible trajectory control. With the flexibility and maximum velocity reported herein (~ 79 ± 6 mm/s), we believe that the presented platform could be potentially applied for biological or chemical analysis where precise manipulation of large amounts of individual droplets is critical. [ABSTRACT FROM AUTHOR]