Tiny Chip Research Articles

Quasi-passive modulation for monolithic GaN photoelectronic circuit

Due to the overlap between the electroluminescence spectrum and spectral responsivity curve, gallium nitride (GaN)-based multi-quantum well (MQW) diodes can modulate and detect light emitted by another diode with the same MQW structure. This enables the realization of a monolithic integrated GaN optoelectronic circuit, integrating an MQW-based transmitter, waveguide, modulator, and receiver on a tiny GaN chip. It is well known that the active region of MQW absorbs high-energy photons within the plane, generating electron-hole pairs and forming photogenerated carriers. The change in free carrier concentration causes variations in the refractive index and absorption characteristics of the waveguide, thereby manipulating light propagation within the waveguide. Based on this physical phenomenon, a quasi-passive modulation scheme is proposed for a monolithic GaN photoelectronic circuit. This scheme achieves optical modulation by connecting a variable resistor between the modulator electrodes, avoiding the need for high-precision external electric fields and complex control circuits. The performance of the quasi-passive modulation was tested through on-chip data transmission and real-time audio signal transmission. The results indicate that quasi-passive modulation is highly feasible in optoelectronic systems and shows great promise as a competitive core module for future large-scale photonic integrated circuits.

Design and construction of a IoT based automated circuit breaker system

Electrocution is a major fatal issue faced by electricians worldwide. A Circuit breaker is a device for automatic switching of electrical devices against overload and short circuits. However, advancements in technology allow for a more sophisticated approach: the cloud-based circuit breaker with a microcontroller and sensors for monitoring the line current and voltage levels. This system switches OFF the affected line when an electrical wire becomes defective, and the lineman may safely repair it. This design integrates real-time monitoring, remote control, and internet connectivity, enhancing electrical safety and offering valuable features for modern applications. At the heart of this design lies a microcontroller (Atmega328) and Esp8266_01(Wi-Fi Module). This tiny computer chip continuously monitors the circuit using current and voltage sensors. By regulating the power supply on the electrical lines, this system protects the safety of the lineman and reduces the risk of electrocution injuries.

Architectural Synthesis of Continuous-Flow Microfluidic Biochips with Connection Pair Optimization

Continuous-flow microfluidic biochips are a type of biochip technology based on microfluidic channels that enable various biological experiments and analyses to be performed on a tiny chip. They have the advantages of a high throughput, high sensitivity, high precision, low cost, and quick response. In the architectural synthesis of continuous-flow microfluidic biochips (CFMBs), prior work has not considered reducing component interconnection requirements, which led to an increase in the number of connection pairs. In this paper, we propose an architectural synthesis flow for continuous-flow microfluidic biochips with connection pair optimization, which includes high-level synthesis, placement, and routing. In the high-level synthesis stage, our method reduces the need for component interconnections, which reduces the number of connection pairs. Our method performs fine-grained binding, ultimately obtaining high-quality binding and scheduling results for flow paths. Based on the high-quality binding results, we propose a port placement strategy based on port correlation and subsequently use a quadratic placer to place the components. During the routing stage, we employ a conflict-aware routing algorithm to generate flow channels to reduce conflicts between liquid transportation tasks. Experimental results on multiple benchmarks demonstrate the effectiveness of our method. Compared with the existing work, the proposed algorithm obtains average reductions of 35.34% in connection pairs, 24.30% in flow channel intersections, 21.71% in total flow channel length, and 18.39% in the execution time of bioassays.

Monolithic III-nitride photonic circuit on a single chip

Inserting multiple quantum wells (MQWs) into a p–n junction, III-nitride MQW diodes can separately function as a light transmitter, modulator, and receiver under different bias conditions. Owing to the spectral overlap between the emission and responsivity spectra, the emitted light from the transmitter is able to be modulated and detected by the modulator and receiver, which have identical MQW structures. Here, we develop a compatible fabrication process to monolithically integrate an III-nitride light transmitter, waveguides, Y-splitter, modulators, Y-combiner, and receiver into a tiny chip. An on-chip 405 nm light communication system is established and exhibits a transmission rate of 260 Mbps in the non-return-to-zero on-off keying scheme. The results pave a feasible route to develop sophisticated monolithic photonic circuit on an III-nitride-on-silicon platform.

Microfluidic sensors platform technology to enhancement fluorescence

The integrated concepts of biology, physics, fluid dynamics, chemistry, material science, and microelectronics provide the foundation of the relatively young area of microfluidics. Various materials may be processed into tiny chips with microscale channels and chambers. Regarding PMMA material and production methods, microfluidic biosensor platform technology also focuses on enhancing rhodamine B's fluorescence via adding carbon nanotubes, with additional benefits including restricted detection, high sensitivity, high stability, repeatability., quick response analysis, low consumption of sample volume, high throughput, also ease of operation applications of these remarkable devices. Keywords: microfluidics, CO2 laser ablation; Confocal Laser Scanning Microscope, PMMA, Carbon nanotubes, fluorescent.

Miniature GaN optoelectronic temperature sensor.

The combination of plastic optical fiber (POF) with monolithically integrated transmitter and receiver is becoming increasingly attractive for the development of miniature optoelectronic sensing systems. Here, we propose a temperature sensing system by integrating a GaN optoelectronic chip with a POF and aluminum (Al) reflector. Owing to the overlap between electroluminescence and responsivity spectra of multiple quantum well (MQW) diodes, both the transmitter and the receiver having identical MQW structures are monolithically integrated on a tiny GaN chip by using the same fabrication process flow. Environmental temperature change leads to thermal deformation in the Al reflector, which reflects the transmitted light back with a light pulse. The reflected light is coupled into the guided POF again and sensed by the on-chip receiver. Finally, the temperature information is read out as electrical signals. When the ambient temperature changes from 20.1°C to 100°C, the optically induced electrical signal decreases from -3.04 µA to -3.13 µA. The results suggest that the monolithically integrated GaN device offers a promising option for optoelectronic temperature sensing systems.

Miniature optical fiber curvature sensor via integration with GaN optoelectronics

Optical fiber curvature sensors have been considered as a promising option for human motion detection due to its good toughness, bending flexibility and anti-electromagnetic interference. However, for wearable devices, the miniature configuration is preferred, and a high integration of the light emitter, receiver and guided fiber is essential to configure the miniaturized sensing system. Here, we present a miniaturized curvature sensing system by integrating a GaN-based optoelectronic chip with the plastical optical fiber (POF). The light emitter and detector are fabricated on a GaN-on-sapphire wafer to form a tiny chip sized at 2.5 times 1.5 mm2. The on-chip photodetector (PD) effectively senses the reflected light intensity, extracting information on the fiber bending deformation. A compact curvature sensing system is demonstrated for finger motion detection with movement angles of 30–90° and frequencies of 0.4, 1, and 1.6 Hz. The results show that the monolithically integrated LED and PD chip can be combined with the POF with reliable operation. The demonstration of the monolithically integrated optoelectronic device suggests a promising potential technology for future wearable fiber optical sensor system.

Design of Thermal-Switchable Absorbing Metasurface Based on Vanadium Dioxide

This letter presents a thermal-switchable absorbing metasurface (TSAM) based on the phase-change material vanadium dioxide (VO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ). A thin film of VO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> was deposited on a sapphire substrate by a magnetron sputtering and then sliced into tiny chips, which can be regarded as thermal-switchable resistors. The surface structure of the TSAM element is realized by loading four VO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> chips into a square metallic loop. Polytetrafluoroethylene is used as the substrate due to its high thermal conductivity compared with foam. The TSAM is on the “absorbing” mode when it is heated underneath and is switched into the “reflecting” mode at room temperature. The absorbing mode is characterized by a wideband absorption (8–22 GHz). A TSAM prototype was fabricated and measured to verify this design.

Microfluidics-Based Urine Biopsy for Cancer Diagnosis: Recent Advances and Future Trends.

Urine biopsy, allowing for the detection, analysis and monitoring of numerous cancer-associated urinary biomarkers to provide insights into cancer occurrence, progression and metastasis, has emerged as an attractive liquid biopsy strategy with enormous advantages over traditional tissue biopsy, such as non-invasiveness, large sample volume, and simple sampling operation. Microfluidics enables precise manipulation of fluids in a tiny chip and exhibits outstanding performance in urine biopsy owing to its minimization, low cost, high integration, high throughput and low sample consumption. Herein, we review recent advances in microfluidic techniques employed in urine biopsy for cancer detection. After briefly summarizing the major urinary biomarkers used for cancer diagnosis, we provide an overview of the typical microfluidic techniques utilized to develop urine biopsy devices. Some prospects along with the major challenges to be addressed for the future of microfluidic-based urine biopsy are also discussed.

A Thermal-Switchable Metamaterial Absorber Based on the Phase-Change Material of Vanadium Dioxide.

This article presents a thermal-switchable metamaterial absorber (TSMA) based on the phase-change material of vanadium dioxide (VO2). VO2 thin film was deposited on sapphire substrate by magnetron sputtering followed by vacuum annealing treatment. Then, the prepared VO2 film was sliced into tiny chips for thermal-switchable elements. The surface structure of TSMA was realized by loading four VO2 chips into a square metallic loop. The absorption frequency of TSMA was located at 7.3 GHz at room temperature and switched to 6.8 GHz when the temperature was heated above the critical phase transition temperature of VO2. A VO2-based TSMA prototype was fabricated and measured to verify this design. The design is expected to be used in metasurface antennas, sensors, detectors, etc.

PathDriver+: Enhanced Path-Driven Architecture Design for Flow-Based Microfluidic Biochips

Continuous-flow microfluidic biochips have attracted high research interest over the past years. Inside such a chip, fluid samples of milliliter volumes are efficiently transported between devices (e.g., mixers, heaters, etc.) to automatically perform various laboratory procedures in biology and biochemistry. Each transportation task, however, requires an exclusive flow path composed of multiple contiguous microchannels during its execution period. Excess/waste fluids, in the meantime, should be discarded by independent flow paths connected to waste ports. All these paths are etched in a very tiny chip area using multilayer soft lithography and driven by flow ports connecting with external pressure sources, forming a highly integrated chip architecture that determines the final performance of biochips. In this article, we propose a new and practical design flow called PathDriver+ (PD+) for the architecture design of microfluidic biochips, integrating the actual fluid manipulations into both high-level synthesis and physical design, which has never been considered in prior work. With this design flow, highly efficient chip architectures with a flow-path network that enables the actual fluid transportation and removal can be constructed automatically. Meanwhile, fluid volume management between devices and flow-path minimization are realized for the first time, thus, ensuring the correctness of assay outcomes while reducing the complexity of chip architectures. Additionally, diagonal channel routing is implemented to fundamentally improve the chip performance. The tradeoff between the numbers of channel intersections and fluidic ports is evaluated to further reduce the fabrication cost of biochips. The experimental results on multiple benchmarks confirm that the proposed design flow leads to high assay execution efficiency and low overall chip cost.

An Adaptive Deep Learning Framework for Fast Recognition of Integrated Circuit Markings

Fast recognition of integrated circuit (IC) markings is an essential but challenging task in electronic device manufacturing lines. This article develops an adaptive deep learning framework to facilitate the fast marking recognition of IC chips. The proposed framework contains four deep learning components, namely, chip segmentation, orientation correction, character extraction, and character recognition. The four components utilize different convolutional neural network structures to guarantee excellent adaptivity to a wide range of IC types and mitigate the influence of the low-quality chip images. In particular, the character extraction model is comprised of two improved label generation strategies and a proposed border correction method, so as to accommodate tiny scale chips and compactly printed markings. Experiments from the chip image dataset of a real laptop manufacturing line reached a recognition Precision of 91.73% and the Recall of 92.93%. The results demonstrate the superiority of the proposed framework to the state-of-the-art models and the effectiveness of handling a great diversity of chips with different scales, shapes, text fonts, marking colors, and layouts.

IC-Based Rectification Circuit Techniques for Biomedical Energy-Harvesting Applications.

Energy harvesting can be achieved through many different mechanisms. Such technology has been drawing researchers’ attention to its practical applications for a decade, as it can be widely applied to countless scenarios. It steals the show in the modern development of the biomedical electronics, especially implantable applications, as it allows the patients to move freely without restriction. To prolong lifetime of the battery inside/outside a patient’s body, the electrical conversion efficiency of the electronic implant is of primary importance in energy harvesting. The conversion can be achieved by a so-called miniaturized rectification circuit (also known as “rectifier”). This study aims to compare different state-of-the-art techniques focusing on the conversion efficiency of the rectification. Particular emphasis is put on semiconductor-based circuits capable of being integrated with tiny chips on the implants.

Ultrathin, Electrically Small Noise Suppression Sheet for Microwave Cavities of 3-D Integrated Circuits: Design Methodology and Realization

Miniaturized microwave cavities constructed by the parallel-plate waveguide (PPW) becomes one of the main propagation pathways of the radio-frequency interference (RFI) in 3-D integrated circuits. It is still challenging to suppress RFI in the practical cavities, where the space is extremely constrained. In this work, the working mechanism and design method of the noise suppression sheet (NSS) is quantitatively studied, serving as an efficient approach to suppress RFI within an electrically small size in these microwave cavities. The analysis is based on the dispersion relationship derivation of the NSS-loaded PPW structure. Both the derived formulas and the numerical study reveal that the imaginary part of the permeability, that is, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu _{i}$ </tex-math></inline-formula> , of the NSS plays a key role in increasing the reflection and attenuation loss, and thus obtaining a high RFI suppression level. Further study indicates even when the NSS’s profile is lower than 10% of the cavity’s height and the length is lower than <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.1\lambda _{0}$ </tex-math></inline-formula> , its suppression level up to 10 dB can be well accomplished, which is deemed difficult to achieve by using conventional methods. Moreover, this method is, respectively, applied in three practical engineering scenarios for the RFI suppression, that is, heatsink package above a chip, power distributed network (PDN), and flexible circuit. Good agreement is observed between the measurement results and the simulated ones, which confirmed the efficacy of our quantitatively developed NSS. The proposed method is promising for broad industrial applications, such as tiny chip packages, multi-channel systems, and flexible electronics.

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Intelligent Micron Optical Character Recognition of DFB Chip Using Deep Convolutional Neural Network

The microcharacter recognition on the distributed feedback (DFB) laser chip is critically essential but a challenging task for the quality control in the incoming chip inspection and optical device manufacturing lines. Hence, this article proposes, designs, and implements a micro-optical character recognition system based on the microscopic imaging system and deep convolutional neural network to facilitate the microcharacter recognition of DFB chips. The proposed micron optical character recognition (MOCR) contains four components, namely, a microscopic imaging system-based visual-based measurement (VBM), character detection, orientation correction, and character recognition. In particular, data augmentation methods considering limited datasets and some chip character features are studied so as to accommodate complex industrial environments and tiny DFB chips. Experiments from the DFB image dataset of a real optical device manufacturing line showed that it reached the accuracy of 98.8&#x0025;, which took a high speed of over 12.8 fps coping with DFB chip images, and saved 72&#x0025; of the labor in the inspection position compared to traditional methods. To the best of our knowledge, there are no existing reports focused on MOCR on DFB chips. So, the first realization and successful application of MOCR played a key role in the intelligent manufacturing and quality traceability of DFB chips and devices in the field of optical communications, which is also of great significance for further accelerating the development of the industrial Internet.

Efficient and Broadband LiGaP2O7:Cr3+ Phosphors for Smart Near‐Infrared Light‐Emitting Diodes

AbstractBroadband near‐infrared (NIR) phosphor‐converted (pc) LED is promising next‐generation tiny light source for smart and broadband NIR spectroscopy technology. However, NIR phosphors suffer from challenges in terms of low quantum efficiency and bandwidth. By selecting a host that has a big bandgap and weakening coupling effect among Cr3+, a novel LiGaP2O7:Cr3+ (LGAP:Cr3+) NIR phosphor that has a high external quantum efficiency (28.3%) is discovered. Under ≈450 nm excitation, LGAP:Cr3+ shows broad NIR emission from 700 to 1100 nm with a bandwidth of ≈170 nm. Importantly, the fabricated pcLED demonstrates bright broadband NIR light and an excellent performance in night vision. The results promise the use of the LGAP:Cr3+ phosphor for high‐performance broadband NIR LED that employs only one tiny blue LED chip.

Toward Wirelessly Cooperated Shape-Changing Computing Particles

Widespread research is being conducted on computational materials. The challenge for the realization of computational materials is how to weave computers into everyday objects consisting of various shapes and form factors. One idea to achieve this vision is to build physical computational particles that can cooperatively communicate among others and, thereby, change the whole shape like clay. Wireless communication and power transfer are keys to making such computing particles happen. Thus, we introduce an approach to embody these particles using multiple tiny IC chips, which wirelessly cooperate with each other. This article shows the current state-of-the-art wireless communication and power transfer technologies integrated into IC chips to achieve fine-grained shape deformation of computers. Moreover, this article also presents recent trends and future directions in shape-changing human-computer interfaces research.

Replication of band structure in an arbitrary wave vector by holographic modulation

Diffraction is a fundamental physical phenomenon that occurs when scattering wave sources are arranged periodically. For example, when x rays are incident on the common salt crystals, diffraction occurs owing to the periodic structure of the chlorine and sodium atoms. Recent advances in nanotechnology have enabled artificial control of the scattering points even in visible wavelengths. These artificial structures are called photonic crystals and are related to many interesting phenomena. Dispersion relations between wave vector and frequency are called band structures. Similar to the band structures of electrons and holes in crystals, photonic bands for dispersion determine the direction of propagation of light waves by diffraction of the periodic structures. Herein, we introduce band engineering which enables multiple replications of bands in arbitrary wave vectors by holographic modulation. We have already realized a patterned light source named ``iPMSEL'' as a typical application of holographically engineered photonic band. The iPMSEL has been realized by combining photonic-crystal surface-emitting lasers and holographic engineering. It can emit arbitrary multiple beam patterns and even photographic images from a tiny semiconductor chip without any optical components. In this paper, we study the iPMSEL from the viewpoint of the photonic-band replication and operation mechanism. While this work is based on photonics, the findings can also be applied to other fields of physics concerned with diffraction. We believe that this work provides useful methods with respect to periodic structures within all scale ranges.

Book Review: Smart City Citizenship

Against the backdrop of the current hyperconnected and highly virialised post-COVID-19 societies, we, ‘pandemic citizens’, wherever we are located now, have already become tiny chips inside an algorithmic giant system that nobody really understands. Furthermore, over the last decade, the increasing propagation of sensors and data collections machines and data collections machines in the so-called Smart Cities by both the public and the private sector has created democratic challenges around AI, surveillance capitalism, and protecting citizens’ digital rights to privacy and ownership. Consequently, the demise of democracy is clearly already one of the biggest policy challenges of our time, and the undermining of citizens’ digital rights is part of this issue, particularly when many ‘pandemic citizens’ will likely be unemployed during the COVID-19 crisis. Amidst the AI-driven algorithmic disruption and surveillance capitalism, this book review sheds light on the way citizens take control of the Smart City, and not viceversa, by revolving around the new book entitled Smart City Citizenship recently published by Elsevier. The book review introduces nine key ideas including how to (1) deconstruct, (2) unplug, (3) decipher, (4) democratise, (5) replicate, (6) devolve, (7) commonise, (8) protect, and (9) reset Smart City Citizenship.