For energy-sustainable Internet of Things (IoT) and wireless sensor networks (WSNs), this paper addresses the minimization of the sole external power consumption in a time-switching simultaneous wireless information and power transfer (TS-SWIPT) based multi-hop decode-and-forward (DF) relay network. In such networks, only the source is grid-powered, while relays operate solely on harvested energy, making global minimization of source power under a stringent end-to-end quality-of-service (QoS) constraint imperative for maximizing network lifetime in green IoT systems. The joint optimization of the source power and the per-hop TS ratios, however, is non-convex. To solve it efficiently and globally, we first transform the problem into an equivalent convex form via logarithmic variable transformations. We then develop a tailored logarithmic barrier interior-point method (IPM) that exploits the problem’s structure. By explicitly leveraging its inherent block-tridiagonal structure, the algorithm achieves per-iteration computational complexity scaling linearly with the number of relays. Simulation results demonstrate global optimality and significant gains of the proposed scheme: for a 5-relay network, it achieves a 5.8-dB source power reduction over the sub-optimal single-step successive convex approximation (SCA) benchmark, as well as a 14.8-dB reduction and a 34.2-percentage-point feasibility rate improvement over the uniform fixed-TS policy. These gains are achieved at a tractable computational cost of approximately 27.5 ms for a 5-relay network. Moreover, a warm-start strategy cuts per-period computation by over 80%, and the solution exhibits strong robustness when evaluated under a realistic logistic (sigmoidal) nonlinear energy harvesting (EH) model and imperfect channel state information (CSI), establishing an excellent performance-efficiency trade-off for practical IoT deployments.

Wireless temperature measurement, compared with traditional temperature measurement methods, can not only offer lower costs and higher convenience but also measure the temperature of the target object in real time and continuously. However, current mainstream-based wireless temperature measurement schemes still face issues such as low accuracy, high power consumption and limited data transmission distance. To this end, this paper proposes a novel ultra-high frequency (UHF) battery-free wireless temperature sensing system. The system utilizes the radio frequency (RF) electromagnetic wave signals in the surrounding environment for energy supply, employs a self-compensating temperature sensor to accurately measure the temperature, and achieves data communication by modulating the electromagnetic wave signals through backscattering. This system is characterized by its low power consumption, long working distance, broad temperature measurement scope and high accuracy. The chip is fabricated in Huahong 0.18 μm 1P6M BCD technology, with a tag chip area of 0.097 mm2. Operating at the frequency of 915 MHz, the RF energy harvesting sensitivity is 17 dBm, and the effective distance of RF energy harvesting can be up to 10 m at the equivalent isotropically radiated power (EIRP) of 36 dBm. With a two-point calibration, the measurement covers a range from 0 to 100 with a mean error of +0.47/0.79 . The average power consumption of the chip is as low as 0.97 μW.

Battery free Internet of Things (BF IoT), which is realized by harvesting ambient energy to power the IoT devices, has many advantages such as low power, low cost, free-maintenance, easy deployment, and environmental protection. As the two key enabling technologies of BF IoT, the integration of energy harvesting, management and backscatter communication (BackCom) is expected to meet practical applications. However, several fundamental issues need to be addressed to fully develop the potential of such integration. In this paper, we propose an ultra-low power energy harvesting and management scheme that effectively reduces the startup and quiescent power consumption. In the case of extremely limited energy harvested, the Long Range (LoRa) BackCom digital waveform generation algorithm with ultra-low power consumption and low complexity is studied, which can support low-power and low-cost micro-controllers (MCUs). Then, a radio frequency (RF) front-end scheme that is compatible with RF energy harvesting (RFEH), BackCom, and On-Off-Keying (OOK) receiving is proposed. On this basis, we design and implement a fully functional BF LoRa Tag, which integrates tag antennas, LoRa BackCom, low-power OOK receiving, multi-parameter real-time sensing, RFEH and management, at a cost of only 6. Our test results show that the BF LoRa Tag can be self-powered by harvesting the RF energy as low as –19 dBm, with the cold-start power as low as 280 nW, the quiescent power as low as 49 nW, the OOK receiving power consumption as low as$1.74~\mu $W, the LoRa BackCom power consumption of only$251~\mu $W, and the communication distance up to 445 meters. Compared with the prototypes in existing literature, the BF LoRa Tag not only has lower power consumption, wider coverage, and the lowest cost, but also has complete system functions. Finally, we discuss the reciprocity between stations and receivers, as well as the BF LoRa cellular communication network, which provides useful references for the practical application and large-scale deployment of BF IoT in the future.

In recent years, micromanipulation technology has achieved extensive applications in industry and life science. Improving the precision and bandwidth of the micromanipulator and simultaneously reducing size, weight, and cost pose significant challenges to the existing micromanipulator design and fabrication methods. Here, we propose a 3-RRS micromanipulator with an origami-inspired spherical joint based on the PC-MEMS process, aiming for miniaturization and cost-effectiveness. The spherical joint allows rotations of 140° around the x-axis approximately, 140° around the y-axis approximately, and 20° around the z-axis approximately. The micromanipulator has weights of 0.8 g, dimensions of 16 mm × 16 mm × 22 mm, and workspace of 0.7 mm3. The end platform of the micromanipulator can be equipped with various effectors to accomplish different kinds of tasks. Experimental results validated its high precision and bandwidth, exhibiting its potential to perform intricate micromanipulation tasks.

Micromanipulation techniques that can achieve controlled fine operations at the micro scale play an important role in biomedical fields including embryo engineering, gene engineering, drug screening, and cell analysis. However, micromanipulation of biological micro-objects, such as cells and micro tissues, suffers from mechanical damage and low efficiency. Several techniques have been introduced to manipulate cells more easily, but most of them are restricted by expensive devices, limited work area, and potential damage to cellular structure. Here we develop a hydrodynamic manipulation method to rotate and transport mouse oocytes, which utilizes acoustic waves and micropipette to generate acoustic radiation force and excite microstreaming. This method can accomplish rotational and translational operations precisely and controllably. We tested the process of trapping, rotation, and transportation of the mouse oocytes, and measured rotational and translational speed with a range of applied voltage. The method was able to shorten the cost time of delivery and posture adjustment before oocyte injection. Our study provides an easy-to-use technique for oocyte manipulation without contact, and it has the potential to be universally applied in many cellular studies.

In the last decade, researchers have been trying to develop many microrobots that mimic the extraordinary abilities of bionts in complex environments. How to fabricate the biomimetic microrobot with satisfying deformability and complex shapes to realize desired precise motion is the key issue. In this paper, we proposed an efficient programable fabrication method of the magnetic soft micro-robot through an on-chip photopolymerization system. The superparamagnetic nanoparticles were compiled according to the magnetic anisotropy and assembled in the micro-robot. Then these nanoparticles were immobilized by photopolymerization of the hydrogel polymer. With this fabrication method, a joint rotation mechanism was first fabricated to characterize the deformation performance under the magnetic field control. Besides, the snake-like micro-robot were also fabricated, and the desired motions were achieved. The experimental results show that the proposed programable on-chip fabrication of magnetic soft micro-robot has the potential to facilitate the development of magnetic microrobots and their applications in the biomedical field.

The magnetic microrobot has become a promising approach in many biomedical applications due to its small volume, flexible motion, and untethered micromachines. The micro-chain robot is one of the most popular magnetic microrobots. However, the uncontrollable magnetic moment direction and quantity of the magnetic beads consisted in the existing self-assembled micro-chain robot limit their locomotion and applications. This paper proposed an on-chip micro-chain robot fabrication method to assemble the magnetic beads with controllable magnetic moment direction and quantity. The bead quantity can be controlled by the structure limits of the microchannel, and the direction of the magnetic moment can be adj usted by the integrated external magnetic field. The assembled magnetic beads are then glued by the hydrogel under UV exposure. The micro-chain robots with different quantities and magnetic moment directions of the magnetic beads were successfully fabricated and tested in experiments. Due to the array structure of the microfluidic device, batch manufacturing of low-cost magnetic robots was achieved in our method. The movement of dual-bead microrobots with two orthogonal magnetic moment directions was analyzed and compared. One of the dual-bead microrobots was applied in the transportation of the hydrogel module using pushing and pulling modes. It indicated that the proposed controllable on-chip fabrication of the magnetic micro-chain robots has the potential to enhance the microrobot ability in biomedical applications.

Microfluidic devices for cell immobilization have significantly advanced the biological analysis at the single-cell level. However, the previous research on immobilization of multiple single cells, especially with deterministic quantities, is insufficient. In this paper, we proposed a novel microfluidic device based on the passive hydrodynamics and the uniform geometric design principle, which can array different numbers of cells in every capture cavity. The capture cavities could be stretched to accommodate more cells, and the trapping force was adjusted by modifying the related geometric parameters of the inside channel. The whole procedure was monitored and further automatized by integrating computer vision technology under a microscope. On the proposed integrated on-chip platform, we realized full-automated arraying of a single cell, two cells, and three cells on a single chip, achieving success rates up to 95%, 75%, and 72%, respectively. As a primary experimental demonstration, the cell viability test of arraying multiple cells with different quantities showed excellent biocompatibility and no significant association between trapping quantity and cell survivability. We envision that the proposed quantity-controllable, high-efficiency microfluidic devices for multiple cell arraying could be a powerful platform for an in-depth study of cell heterogeneity and cell communication between multiple cells.Note to Practitioners—This article is motivated by the biomedical applications of multi-cell arraying. The designed microfluidic devices employ passive hydrodynamics, and the capture cavities are stretched to accommodate different numbers of cells. The whole arraying procedures are automatized using computer vision technology. Simulations and experiments demonstrate the high efficiency, controllability of the cell quantity, and excellent biocompatibility.

Radio-frequency (RF)-powered backscattering communication (BC) has many advantages, such as low-power consumption, battery-free, small size, low cost, full sealing, manual maintenance-free, and easy mass deployment. However, the weak RF energy harvested and the short BC distance have become the two critical obstacles in the real-world implementation of this potential technology. In this article, we propose a high-sensitivity RF energy harvesting (RFEH) and long-distance BC method, and for the first time, we demonstrate the RF-powered self-sustainable long-distance BC device named RFEH LoRa. In order to improve RFEH sensitivity, an ultralow-power (ULP) consumption voltage monitoring and startup control circuit topology is designed to reduce the power consumption to 245 nanowatt (nW) during the accumulation of RF energy. While in order to increase the BC distance, a direct digital frequency synthesis technology is used to generate a linear frequency modulation square wave sequence conforming to the LoRa specifications based on the ULP microcontroller unit, and the square wave is used to drive an RF switch to achieve long-distance BC of hundreds of meters. Test results show that the instantaneous BC current is as low as 130 microampere ( μA), and the standby current is only 52 nanoampere (nA). RFEH LoRa is implemented with commercial off-the-shelf components. It can self-startup by harvesting RF energy as low as -22.5 dBm, and send its sensing data to the receiver of 381-m away.

In this paper, an automated tracking system with head and tail recognition for time-lapse observation of free-moving C. elegans is presented. In microscale field, active C. elegans can move out of the view easily without an automated tracking system because of the narrow field of view and rapid speed of C. elegans. In our previous works, we constructed an automated platform with 3D freedom to track centroid region of the nematode successfully. However, tracking time was not long enough to support a full time-lapse observation. Our proposed system in this study integrate the detection method in horizontal plane with depth evaluation more tightly. Tracking time and response speed have been greatly improved. Besides, we make full use of curvature calculation to make the system recognize the head and tail of C. elegans and the recognition rate can be up to 95%. The results demonstrate that the system can fully achieve automated long-term tracking of a free-living nematode and will be a nice tool for C. elegans behavioral analysis.

We have successfully achieved manipulation and assembly of microbeads having the size of 100μm diameter by hemispherical end-effectors with high stability and accuracy. The motivation of achieving assembly of actual cells lies in the great significance of it in tissue regeneration and cell analysis. Firstly, the most difficult problem we need to solve is the releasing problem caused by adhesion force. The viscosity on cell surface is much larger than the microbeads which makes cell releasing challenging. Secondly, the cell can generate its deformation, then contact area with end-effector will change during grasping process. This may influence the adhesion force and also bring problem to releasing. Thirdly, cell is much smaller, around 15μm in diameter, so we need to fabricate smaller end-effector to achieve successful manipulation and ensure the stability in the meantime. In this paper, we realize the manipulation by decreasing the adhesion forces and apply vibration to release a cell stably. We found the appropriate scale size for the end-effector is around 10μm diameter. It can not only grasp a 15μm cell but also bring little interference to the environment. As a demonstration of the proposed manipulation method, the repeated experiments were conducted to explore the dependence of adhesion force on the grasping distance, which can be helpful in the improvement of successful rate. Finally, we achieved automatic cell assembly using Hela cells.

A Wi‐Fi scatter communication method based on microcontroller unit (MCU) is proposed, and an ultra‐low power micro Wi‐Fi scatter communication device μWi‐Fi is designed and implemented. First, according to the characteristics of the microcontroller, the software virtual modulation method and the serial communication port direct memory access (DMA) transmission method is proposed to realise Wi‐Fi scattering communication. Then the MCU + exclusive OR (XOR) baseband architecture is proposed to further reduce the main frequency of the microcontroller and the system power consumption. The communication test and power consumption measurement results show that μWi‐Fi can generate signals conforming to the IEEE802.11b standard, which can be received and forwarded by universal Wi‐Fi routers. Its effective communication distance reaches 15 m, its communication peak current reaches 720 μA, and its standby current reaches 390 nA. Compared with traditional internet of things (IOTs) Wi‐Fi devices, μWi‐Fi can not only reduce the power consumption of Wi‐Fi communication by 2–3 orders but also has a simple composition and low cost, which is very helpful for the rapid development of Wi‐Fi IoT products.

Nowadays single cell analysis becomes a more and more important method to gather the information of individual cells and study the heterogeneity of cells caused by random expression of gene, protein and the level of metabolism. Many device and technologies of single cell analysis have been developed to meet these needs. In this paper, we presented a high-throughput microchannel for single cell immobilization with small sheer pressure. It features high density arrays, which can accommodate up to 130~300 traps within 1~2 mm2. According to our experiment, about 91% of capture unit can be occupied by the single cell in 40 s, using the optimized structure of microchannels. Therefore, we expect that the high throughput microchannels can be of great importance for the biological research.

An efficient SAR raw signal simulator accounting for antenna attitude variations is presented here, based on the 2-demensional Fourier domain formulation of SAR raw signal in presence of antenna beam pointing errors. It can meet the requirements of InSAR system simulation to deal with the extended scenes. The validity limit is analyzed to show that this algorithm is suit for the simulation of practical systems.