Rotibot: Use of Rotifers as Self‐Propelling Biohybrid Microcleaners

Self‐propelled biohybrid microrobots, employing marine rotifers as their engine, named “rotibot,” are presented and their practical utility and advantages for environmental remediation are demonstrated. Functionalized microbeads are attached electrostatically within the rotifer mouth and aggregated inside their inner lip. The high fluid flow toward the mouth, generated by the strokes of rotifer cilia bands, forces an extremely efficient transport of the contaminated sample over the active surfaces of the functionalized microbeads. The reactive particles confined around the rotifer's lip are thus exposed to a high flow rate of the pollutant solution, resulting in dramatically accelerated decontamination processes, without external mixing or harmful fuels. Theoretical simulations, modeling the greatly enhanced fluid dynamic associated with such built‐in mixing effect, correlate well with the experimental observations. The rotibot thus proves to be an effective, versatile, and robust dynamic microcleaning platform for removing diverse environmental pollutants. Microbeads functionalized with lysozyme and organophosphorus hydrolase enzymes are shown to be extremely useful for enzymatic biodegradation of Escherichia coli and the nerve agent methyl paraoxon, respectively, while ligand (meso‐2,3‐dimercaptosuccinic acid) modified beads are used for removing heavy metal contaminants. Rotifer‐based biohybrid microrobots hold considerable promise as self‐propelling dynamic pumps for diverse large‐scale environmental remediation applications.     

Biohybrid Carbon Nanotube/Agarose Fibers for Neural Tissue Engineering

We report a novel approach for producing carbon nanotube fibers (CNF) composed with the polysaccharide agarose. Current attempts to make CNF's require the use of a polymer or precipitating agent in the coagulating bath that may have negative effects in biomedical applications. We show that by taking advantage of the gelation properties of agarose one can substitute the bath with distilled water or ethanol and hence reduce the complexity associated with alternating the bath components or the use of organic solvents. We also demonstrate that these CNF can be chemically functionalized to express biological moieties through available free hydroxyl groups in agarose. We corroborate that agarose CNF are not only conductive and nontoxic, but their functionalization can facilitate cell attachment and response both in vitro and in vivo. Our findings suggest that agarose/CNT hybrid materials are excellent candidates for applications involving neural tissue engineering and biointerfacing with the nervous system.     

Simulation and Fabrication of Stronger,Larger, and Faster Walking Biohybrid Machines

Advancing biologically driven soft robotics and actuators will involve employing different scaffold geometries and cellular constructs to enable a controllable emergence for increased production of force. By using hydrogel scaffolds and muscle tissue, soft biological robotic actuators that are capable of motility have been successfully engineered with varying morphologies. Having the flexibility of altering geometry while ensuring tissue viability can enable advancing functional output from these machines through the implementation of new construction concepts and fabrication approaches. This study reports a forward engineering approach to computationally design the next generation of biological machines via direct numerical simulations. This was subsequently followed by fabrication and characterization of high force producing biological machines. These biological machines show millinewton forces capable of driving locomotion at speeds above 0.5 mm s^?1. It is important to note that these results are predicted by computational simulations, ultimately showing excellent agreement of the predictive models and experimental results, further providing the ability to forward design future generations of these biological machines. This study aims to develop the building blocks and modular technologies capable of scaling force and complexity of these devices for applications toward solving real world problems in medicine, environment, and manufacturing.     

Conditional DNA‐Protein Interactions Confer Stimulus‐Sensing Properties to Biohybrid Materials

Interactive materials that specifically respond to environmental stimuli hold high promise as energy‐autonomous sensors and actuators in biomedicine, analytics or microsystems engineering. However, the implementation of materials specifically responsive to a given small molecule has so far been hampered by a lack of generically applicable stimulus sensors. In this study, a novel and likely general strategy for the synthesis of biohybrid materials with desired stimulus specificity is established. The strategy is based on allosterically regulated DNA‐binding proteins, a conserved protein family that has evolved in prokaryotes to sense and respond to most diverse molecules in order to enable bacterial survival in a changing environment. The novel hydrogel design concept is demonstrated with the example of single‐chain TetR, a protein that binds the tetO DNA motif and dissociates thereof in the presence of the antibiotic tetracycline. Therefore, linear polyacrylamide is crosslinked via the TetR/tetO interaction to a biohybrid material that can subsequently be dissolved by tetracycline in a dose‐dependent manner. This drug‐induced dissolution is applied for the adjustable release of the cytokine interleukin 4 in a tetracycline‐dependent manner. The design concept developed in this study might serve as a blueprint for the synthesis of biohybrid materials responsive to drugs, metabolites or toxins by replacing TetR/tetO with another protein/DNA pair showing the desired stimulus specificity.     

Rapid and Continuous Hydrodynamically Controlled Fabrication of Biohybrid Microfibers

Cell encapsulation is critical for many biotechnology applications including environmental remediation, bioreactors, and regenerative medicine. Here, the development of biohybrid microfibers comprised of encapsulated bacteria in hydrogel matrices produced on‐chip using microfluidics is reported. The fiber production process utilizes hydrodynamic shaping of a cell‐laden core fluid by a miscible sheath fluid. Production of the fibers containing viable bacteria was continuous in contrast to the more typical methods in which cells infiltrated or were attached to prepared fibers. The biohybrid fibers were composed of poly (ethylene glycol dimethacrylate) matrices and individually both E. coli and B. cereus were explored as model cellular payloads. Post processing growth curves (24 h) of bacteria within fibers were in excellent agreement with that of controls suggesting minimal impact. Finally, the biohybrid fibers showed even distribution of encapsulated cells and >90% cell viability.     

Direct 3D Printing of High Strength Biohybrid Gradient Hydrogel Scaffolds for Efficient Repair of Osteochondral Defect

The emerging 3D printing technique allows for tailoring hydrogel‐based soft structure tissue scaffolds for individualized therapy of osteochondral defects. However, the weak mechanical strength and uncontrollable swelling intrinsic to conventional hydrogels restrain their use as bioinks. Here, a high‐strength thermoresponsive supramolecular copolymer hydrogel is synthesized by one‐step copolymerization of dual hydrogen bonding monomers, N‐acryloyl glycinamide, and N‐[tris(hydroxymethyl)methyl] acrylamide. The obtained copolymer hydrogels demonstrate excellent mechanical properties—robust tensile strength (up to 0.41 MPa), large stretchability (up to 860%), and high compressive strength (up to 8.4 MPa). The rapid thermoreversible gel ? sol transition behavior makes this copolymer hydrogel suitable for direct 3D printing. Successful preparation of 3D‐printed biohybrid gradient hydrogel scaffolds is demonstrated with controllable 3D architecture, owing to shear thinning property which allows continuous extrusion through a needle and also immediate gelation of fluid upon deposition on the cooled substrate. Furthermore, this biohybrid gradient hydrogel scaffold printed with transforming growth factor beta 1 and β‐tricalciumphosphate on distinct layers facilitates the attachment, spreading, and chondrogenic and osteogenic differentiation of human bone marrow stem cells (hBMSCs) in vitro. The in vivo experiments reveal that the 3D‐printed biohybrid gradient hydrogel scaffolds significantly accelerate simultaneous regeneration of cartilage and subchondral bone in a rat model.     

Photosynthetic Biohybrid Nanoswimmers System to Alleviate Tumor Hypoxia for FL/PA/MR Imaging‐Guided Enhanced Radio‐Photodynamic Synergetic Therapy

Biohybrid microswimmers have recently shown to be able to actively perform in targeted delivery and in vitro biomedical applications. However, more envisioned functionalities of the microswimmers aimed at in vivo treatments are still challenging. A photosynthetic biohybrid nanoswimmers system (PBNs), magnetic engineered bacteria‐Spirulina platensis, is utilized for tumor‐targeted imaging and therapy. The engineered PBNs is fabricated by superparamagnetic magnetite (Fe₃O₄ NPs) via a dip‐coating process, enabling its tumor targeting ability and magnetic resonance imaging property after intravenous injection. It is found that the PBNs can be used as oxygenerator for in situ O₂ generations in hypoxic solid tumors through photosynthesis, modulating the tumor microenvironment (TME), thus improving the effectiveness of radiotherapy (RT). Furthermore, the innate chlorophyll released from the RT‐treated PBNs, as a photosensitizer, can produce cytotoxic reactive oxygen species under laser irradiation to achieve photodynamic therapy. Excellent tumor inhibition can be realized by the combined multimodal therapies. The PBNs also possesses capacities of chlorophyll‐based fluorescence and photoacoustic imaging, which can monitor the tumor therapy and tumor TME environment. These intriguing properties of the PBNs provide a promising microrobotic platform for TME hypoxic modulation and cancer theranostic applications.     

Cell Generator: A Self‐Sustaining Biohybrid System Based on Energy Harvesting from Engineered Cardiac Microtissues

Biohybrid soft robotic devices present unique advantages for designing biologically active machines that can dynamically sense and interact with complex bioelectrical signals. Here, a controllable cell‐based machine is developed that harvests energy from arrays of beating cardiomyocytes to generate electricity for biomedical microscale robotic applications. The “Cell Generator” device is based on an array of piezoelectric microcantilevers wrapped with 3D patterned cardiac cells. Spontaneous contraction of the engineered cardiac constructs provides the source of mechanical energy for electricity generation. It is demonstrated that a single “Cell Generator” unit with 40 cantilevers can output peak voltages of ≈70 mV, and a larger array of 540 cantilevers can directly generate a pulsed output as high as ≈1 V. When integrated with an electrical rectification and storage circuit, it is further shown that the “Cell Generator” can provide functional outputs and work as a self‐powered neural stimulator to evoke action potentials in cultured neuronal networks. This demonstration of “Cell Generator” technology provides an innovative perspective of exploiting live biological powering system on biomedical microscale robotic devices in the human body.     

Remote‐Controlled Hydrogel Depots for Time‐Scheduled Vaccination

Remote‐controlled drug depots represent a highly valuable tool for the timely controlled administration of pharmaceuticals in a patient compliant manner. Here, the first pharmacologically controlled material that allows for the scheduled induction of a medical response in mice is described. To this aim, a novel, humanized biohybrid material that releases its cargo in response to a small‐molecule stimulus licensed for human use is developed. The functionality of the material in mice is demonstrated by the remote‐controlled delivery of a vaccine against the oncogenic human papillomavirus type 16. It is shown that the biohybrid depot‐mediated immunoprotection is equivalent to the classical multi‐injection‐based vaccination. These results indicate that this material can be used as a universal remote‐controlled vehicle for the patient‐compliant delivery of vaccines and pharmaceuticals.     

光电双基区晶体管光控脉冲振荡器的实验研究

光电双基区晶体管（ＰＤＵＢＡＴ）是一种能产生“Ｎ”型光电负阻特性的新型光电负阻器件。通过对试制出的样管进行测试,发现ＰＤＵＢＡＴ在无外接电感的情况下即可发生脉冲振荡。脉冲振荡的频率和振幅均受到入射光强度的调制,即随光强的增大,振荡频率增加,振由减小。最后,对该器件的应用及发展前景进行了讨论。     

用于光控相控阵雷达的空间光调制器

空间光调制器是光信息处理机的基本结构单元,它能根据电驱动信号或光驱动信号,随时修正与空间和时间有关的读出光束的偏振、相位和幅度.介绍了适用于光控相控阵雷达系统的空间光调制器,包括它们的结构、原理和性能.     

RTD/HPT光控单-双稳转换逻辑单元

以光接收器件代替RTD MOBILE(RTD单-双稳转换逻辑单元)电路中的HEMT或HBT,可构成光控MOBILE电路。在比较了四种光控MOBILE结构的基础上,选择RTD/HPT光控结构,重点分析讨论了RTD/HPT光控MOBILE的工作原理,当光控MOBILE的输入光功率超过一个临界值时,MOBILE的输出电压便会从高电平跳变到低电平;由HPT光增益理论分析了提高HPT性能的措施以及HPT设计中应该注意的问题;介绍了以Si光三极管代替HPT,通过模拟实验,验证了RTD/HPT光控MOBILE的逻辑功能。     

激光辅助照明主动近红外成像系统

研制了一种激光辅助照明主动近红外成像组件。该组件使用半导体激光光纤耦合器件作为夜视光源,通过其在暗场自然环境下的成像验证了光源补光性能和选用的CCD芯片对特定波段光源具有较高的响应度。该组件可实现全天候成像,不受外界照度的制约,可广泛应用于科研、监控等领域。     

Fast and Ample Light Controlled Actuation of Monodisperse All-DNA Microgels

The assembly of adaptive hierarchical soft materials that resemble living tissues requires responsive building blocks of controlled dimensions. While DNA self-assembly provides an exceptional tool for nanoscale architectural control, responsive DNA microstructures remain scarce. Here, two challenges controlling the size of DNA microstructures and embedding them with fast and ample structural response are addressed. For size-control, arrested phase separation and microfluidic confinement are combined to produce monodisperse all-DNA particles. For responsiveness, a light controlled coil-globule transition of the microgel DNA network powered by an azobenzene cationic surfactant is implemented. The photoinduced trans-cis isomerization of the azobenzene moiety reduces its affinity for DNA which results in fast, large amplitudes microgel swelling. Finally, the assembly of light responsive microgel superstructures is demonstrated as proof-of-concept hierarchical all-DNA materials.     

Remote Steering of Self‐Propelling Microcircuits by Modulated Electric Field

The principles and design of “active” self‐propelling particles that can convert energy, move directionally on their own, and perform a certain function is an emerging multidisciplinary research field, with high potential for future technologies. A simple and effective technique is presented for on‐demand steering of self‐propelling microdiodes that move electroosmotically on water surface, while supplied with energy by an external alternating (AC) field. It is demonstrated how one can control remotely the direction of diode locomotion by electronically modifying the applied AC signal. The swimming diodes change their direction of motion when a wave asymmetry (equivalent to a DC offset) is introduced into the signal. The data analysis shows that the ability to control and reverse the direction of motion is a result of the electrostatic torque between the asymmetrically polarized diodes and the ionic charges redistributed in the vessel. This novel principle of electrical signal‐coded steering of active functional devices, such as diodes and microcircuits, can find applications in motile sensors, MEMs, and microrobotics.