Quantitative Magnetic Separation of Particles and Cells Using Gradient Magnetic Ratcheting

Extraction of rare target cells from biosamples is enabling for life science research. Traditional rare cell separation techniques, such as magnetic activated cell sorting, are robust but perform coarse, qualitative separations based on surface antigen expression. A quantitative magnetic separation technology is reported using high‐force magnetic ratcheting over arrays of magnetically soft micropillars with gradient spacing, and the system is used to separate and concentrate magnetic beads based on iron oxide content (IOC) and cells based on surface expression. The system consists of a microchip of permalloy micropillar arrays with increasing lateral pitch and a mechatronic device to generate a cycling magnetic field. Particles with higher IOC separate and equilibrate along the miropillar array at larger pitches. A semi‐analytical model is developed that predicts behavior for particles and cells. Using the system, LNCaP cells are separated based on the bound quantity of 1 μm anti‐epithelial cell adhesion molecule (EpCAM) particles as a metric for expression. The ratcheting cytometry system is able to resolve a ±13 bound particle differential, successfully distinguishing LNCaP from PC3 populations based on EpCAM expression, correlating with flow cytometry analysis. As a proof‐of‐concept, EpCAM‐labeled cells from patient blood are isolated with 74% purity, demonstrating potential toward a quantitative magnetic separation instrument.     

Path Planning and Control of a Cooperative Three-Robot System Manipulating Large Objects

After a brief review of the current research on multi-robot systems, the paper presents a path planning and control scheme for a cooperative three-robot system transferring/manipulating a large object from an initial to a desired final position/orientation. The robots are assumed to be capable of holding the object at three points that define an isosceles triangle. The mode of operation adopted is that of a master-and-two-slave robots. The control scheme employs the differential displacement of the object which is transformed into that of the end-effector of each robotic arm, and then used to compute the differential displacements of the joints of the robots. The scheme was applied to several 3-robot systems by simulation and proved to be adequately effective, subject to certain conditions regarding the magnitude of the differential displacements. Here, an example is included which concerns the case of three Stäubli RX-90L robots.     

Electrically Sensitive Plasmonic Photonic Crystals for Dynamic Upconversion Manipulation

Local optical field modulation using plasmonic materials or photonic crystals provides a powerful strategy for enhancing upconversion emission of lanthanide-doped upconversion nanocrystals (UCNPs). However, it is restricted to static UC enhancement and the corresponding dynamic modulation of UC is yet to be reported, limiting its practical applications in information devices. Here, a dynamic UC modulation system is reported through electric stimulation by integrating UCNPs with electrically sensitive WO_3−x plasmonic photonic crystals (PPCs). The tunable emission enhancement of UCNPs varying from five to 26 folds is achieved in WO_3−x PPCs/UCNPs hybrids through external electric stimulation within +1.6 and −1.6 V. It stems from the reversible control of the photonic bandgaps and localized surface plasmon resonance of WO_3−x PPCs, ascribed to the variation of refractive index and oxygen vacancy of WO_3−x, induced by the reversible change of atomic ratio of W⁵⁺ to W⁶⁺ under different applied voltages. Moreover, the electrically triggered information encryption devices are developed, employing a programmable logic gate array based on WO_3−x PPCs/UCNPs with the ability to convert information-encrypted electrical signals into visible patterns. These observations offer a new attempt to manipulate the UC and will simulate the new applications in the display and optical storage devices.     

A self-adjusting and modular supervisory control algorithm for planar dexterous manipulation

Many applications require precise handling and manipulation of delicate objects. In some cases, the object must be transported to a new location following a strict travel path including time-related constraints. This paper presents a self-adjusting modular control algorithm for dexterous manipulation of planar objects using multiple manipulators with precise path and timing deliveries. The popular caging approach is simple, and usually effective when manipulating objects with multiple devices but can fail following complex paths with orientation adjustments under time-critical tracking requirements. The proposed approach exploits the dynamics of the object in real-time using tracking control and allocates the force that needs to be applied by each manipulator based on their current position around the object to maximize their capability to push in the direction of the contact angle. The new algorithm is self-adjusting and modular; It can adjust its force allocation according to configuration changes during operation, and manipulators execute the same algorithm regardless of their number. The advantages of the new approach are successfully demonstrated both with simulations and testbed experiments, including orientation tracking, which is not typically featured with the caging approach. Conditions to check when the new algorithm is most effective are also analyzed. The closed-loop stability and performance of the new algorithm are also studied and necessary conditions are identified.     

Field-Free Manipulation of Skyrmion Creation and Annihilation by Tunable Strain Engineering

Creation and annihilation of skyrmions are two crucial issues for constructing skyrmion-based memory and logic devices. To date, these operations were mainly achieved by means of external magnetic, electrical, and optical modulations. In this work, we demonstrated an effective strain-induced skyrmion nucleation/annihilation phenomenon in [Pt/Co/Ta]_n multilayers utilizing the shape memory effect of a TiNiNb substrate. A tunable tensile strain up to 1.0% can be realized in the films by thermally driving phase transition of the substrate, which significantly decreases the nucleation field of skyrmions by as many as 400 Oe and facilitates the field-free manipulation of skyrmions with the strain. Such a strain effect can be attributed to the synergetic interplay of the planar magnetic moment twirling and decrement of interfacial Dzyaloshinskii–Moriya interaction. In addition, the strain tunability is found to be strongly related to the strain direction due to magnetoelastic interaction. These findings provide a novel strategy for developing strain-assisted skyrmion-based memory and logic devices.     

Stretchable and Ultrasensitive Intelligent Sensors for Wireless Human–Machine Manipulation

Metallic two-dimensional conductive nanomaterials are extensively explored in stretchable strain sensors, which have promising applications ranging from health monitoring to human–machine manipulation. However, there are limited materials available in this category, and their sensing abilities need to be strengthened. Herein, a controllable deoxidation–nitridation strategy via the pyrolysis of an amine nitrogen source to synthesize oxygen-doped vanadium nitride (VNO) nanosheets with high conductivity is reported. Its metallic characteristics and low dimensionality, together with layer-to-layer slippage make VNO particularly suitable for stretchable strain sensors with remarkable performance, including extraordinary sensitivity (a maximum gauge factor of 2667), wide detection range (0–100%), high durability (over 6000 cycles), and rapid response (44 ms). Furthermore, the strain sensors can capture various physiological signals; in particular, a state-of-the-art wireless vehicle control system designed for differently abled people is fabricated based on the sensors. Moreover, by engineering the thickness of the VNO layer, it can behave as an elastic conductor, demonstrating its feasibility for stretchable wiring.     

Noncontact All-In-Situ Reversible Reconfiguration of Femtosecond Laser-Induced Shape Memory Magnetic Microcones for Multifunctional Liquid Droplet Manipulation and Information Encryption

Shape memory polymers can change their shapes in a controlled way under external stimuli and thus promote the development of smart devices, soft robotics, and microfluidics. Here, a kind of iron particles (IPs) doped shape memory microcone is developed for noncontact all-in-situ reversible tuning between the tilted and upright state under near-infrared (NIR) irradiation and magnetic field (MF) actuation. The magnetic microcones are simply fabricated by a laser-ablated replica-molding strategy so that their height can be precisely controlled by adjusting the laser machining parameters. In addition, it is found that the droplets can be transported unidirectionally on the tilted microcones, which is related to the variation of the adhesion force induced by the length of the triple contact line (TCL). Finally, other multifunctional applications have also been realized, such as, selective droplet release, information encryption, rewritable display, and reusable temperature switch. This work may provide a facile strategy for developing multiresponsive smart devices based on shape memory polymers.     

Mechanical Manipulation of Nano-Twinned Ferroelectric Domain Structures for Multilevel Data Storage

Ferroelectric materials feature a switchable spontaneous electric polarization and can enable low-power logic and nonvolatile memories. These applications require reliable and precise control of ferroelectric domains and domain walls in ferroelectric thin films. Mechanical manipulation is a promising route to engineer ferroelectric domains, but it has proved ineffective when going beyond a critical thickness. Here, multi-step 90° switching polarization reversal processes in (111)-oriented PbZr_0.2Ti_0.8O₃ thin films by applying mechanical forces along the direction parallel to the domain bands are reported. By probing the interrelationships between the relevant order parameters, coupled lattice distortion and piezoelectricity is revealed to facilitate domain switching from downward to upward in PbZr_0.2Ti_0.8O₃, a mechanism that is supported by the evolution of domains and electrical performances at different temperatures and under varying pressures, respectively. The multi-step domain reversal processes render PbZr_0.2Ti_0.8O₃ thin films an excellent candidate for multilevel data storage. The study's results have implications for the manipulation of polarization switching in ferroelectrics and open an avenue to domain reversal driven by mechanical loads for the development of next-generation ferroelectric devices.     

Bionic Adaptive Thin-Membranes Sensory System Based on Microspring Effect for High-Sensitive Airflow Perception and Noncontact Manipulation

Recently airflow sensors based on mechanical deformation mechanisms have drawn extensive attention due to their favorable flexibility and sensitivity. However, the fabrication of highly sensitive and self-adaptive airflow sensors in a simple, controllable, and scalable method still remains a challenge. Herein, inspired by the wing membrane of a bat, a highly sensitive and adaptive graphene/single-walled nanotubes-Ecoflex membrane (GSEM) based airflow sensor mediated by the reversible microspring effect is developed. The fabricated GSEM is endowed with an ultralow airflow velocity detection limit (0.0176 m s⁻¹), a fast response time (≈1.04 s), and recovery time (≈1.28 s). The GSEM-based airflow sensor can be employed to realize noncontact manipulation. It is applied to a smart window system to realize the intelligent, open, and close behaviors via a threshold control. In addition, an array of airflow sensors is effectively designed to differentiate the magnitude and spatial distribution of the applied airflow stimulus. The GSEM-based airflow sensor is further integrated into a wireless vehicle model system, which can sensitively capture the flow velocity information to realize a real-time direction of motion manipulation. The microspring effect-based airflow sensing system shows significant potentials in the fields of wearable electronics and noncontact intelligent manipulation.     

Verification of physical designs using an integrated reverse engineering flow for nanoscale technologies

Considering the potential risks of piracy and malicious manipulation of complex integrated circuits using worldwide distributed manufacturing sites, an effective and efficient reverse engineering process allows the verification of the physical layout against the reference design. This paper provides an overview of the current process and details on a new tool for the acquisition and synthesis of large area images and the recovery of the design from a physical device. Using this reverse engineering process on a physical chip layout, a circuit graph based partitioning of circuit blocks and an Elliptic Curve Cryptography (ECC) module identification will be performed. For the first time, the error between the generated layout and the design GDS layout will be compared quantitatively as a figure of merit (FoM). We propose a new classification of malicious manipulations based on their layout impact.