Design, fabrication and application of magnetically actuated micro/nanorobots: a review.

Magnetically actuated micro/nanorobots are typical micro- and nanoscale artificial devices with favorable attributes of quick response, remote and contactless control, harmless human-machine interaction and high economic efficiency. Under external magnetic actuation strategies, they are capable of achieving elaborate manipulation and navigation in extreme biomedical environments. This review focuses on state-of-the-art progresses in design strategies, fabrication techniques and applications of magnetically actuated micro/nanorobots. Firstly, recent advances of various robot designs, including helical robots, surface walkers, ciliary robots, scaffold robots and biohybrid robots, are discussed separately. Secondly, the main progresses of common fabrication techniques are respectively introduced, and application achievements on these robots in targeted drug delivery, minimally invasive surgery and cell manipulation are also presented. Finally, a short summary is made, and the current challenges and future work for magnetically actuated micro/nanorobots are discussed.

[Effects of postconditioning on autophagy of lung ischemic reperfusion injury in rats].

OBJECTIVE: To explore the effects of postconditioning on autophagy of lung injury in situ during lung ischemic reperfusion. METHODS: Twenty-four male Sprague-Dawley rats were randomly divided into 3 groups of sham-operated (S), ischemic-reperfusion (I/R) and ischemic postconditioning (IpostC) (n = 8 each). All underwent left thoracotomy after anesthesia. In the S group, a line was only placed around left hilum but not fastened. In the I/R group, a line was fastened to block the blood flow of left lung for 30 min and then loosened for reperfusion for 120 min. In the IpostC group, after blocking the blood flow of left lung for 30 min, left hilum was fastened for 30 sec and loosened for 30 sec. Lung tissues were measured by Western blot. Histopathological changes of lung tissues were observed, lung injury scores calculated and autophagic vacuoles determined by electron microscope. RESULTS: The relative expression levels of mammalian target of rapamycin (mTOR) and phosphorylated mTOR (p-mTOR) in group I/R (0.40 ± 0.03, 0.33 ± 0.10) were not different with those of group S (0.37 ± 0.07, 0.31 ± 0.10) (both P > 0.05). However, both significantly increased in group IpostC (0.46 ± 0.09, 0.55 ± 0.07) (both P < 0.05). As compared with group S, the relative expression level of LC3-IIand lung injury score significantly increased in groups I/R and IpostC (0.53 ± 0.08, 0.38 ± 0.03 vs 0.25 ± 0.06; 15.79 ± 1.33, 11.67 ± 1.55 vs 5.58 ± 0.39) while obviously declined in group IpostC versus group I/R (all P < 0.05). In group I/R, neutrophil infiltration, interstitial edema, atelectasis and hyaline membrane formation were observed microscopically in lung tissues and the formation of autophagic vacuoles was evident under electron microscope. The changes of group IpostC were milder than those of group I/R. CONCLUSIONS: Ischemic postconditioning has protective effects on lung ischemic reperfusion injury by attenuating autophagy. It may be related with strengthening mTOR.

Self-Patterning of Highly Stretchable and Electrically Conductive Liquid Metal Conductors by Direct-Write Super-Hydrophilic Laser-Induced Graphene and Electroless Copper Plating.

Stretchable electrodes are desirable in flexible electronics for the transmission and acquisition of electrical signals, but their fabrication process remains challenging. Herein, we report an approach based on patterned liquid metals (LMs) as stretchable electrodes using a super-hydrophilic laser-induced graphene (SHL-LIG) process with electroless plating copper on a polyimide (PI) film. The LMs/SHL-LIG structures are then transferred from the PI film to an Ecoflex substrate as stretchable electrodes with an ultralow sheet resistance of 3.54 mΩ per square and excellent stretchability up to 480% in elongation. Furthermore, these electrodes show outstanding performances of only 8% electrical resistance changes under a tensile strain of 300%, and strong immunity to temperature and pressure changes. As demonstration examples, these electrodes are integrated with a stretchable strain sensing system and a smart magnetic soft robot toward practical applications.

Laser-Sculptured Hierarchical Spinous Structures for Ultra-High-Sensitivity Iontronic Sensors with a Broad Operation Range.

Tactile pressure sensing over a wide operation range (>1 MPa) is challenging for a variety of applications in fields such as aviation, oceanography, and biomedicine. Recently, innovative strategies have been utilized to improve the performances of tactile sensors using specially designed structures, dielectric layers, and electrodes. Here, a hierarchical structural design based on ionic gel films has been utilized to build iontronic pressure sensors with ultrahigh sensitivities and broad operation ranges. Sculptured patterns made by a controlled CO2 laser scanning process have been produced on polyimide films to achieve two kinds of protrusion structures for high specific surface areas and strength to withstand high pressure. The iontronic sensor has been constructed by adding two screen-printed electrodes of high surface areas to achieve an ultrahigh sensitivity of 2593 kPa-1 and a wide pressure range from 0 Pa to 3.36 MPa. The prototype device also has a fast response and recovery time of 26 and 13 ms, respectively, and an excellent mechanical durability in the endurance test of over 2700 repeated loading and unloading cycles under a pressure of 1 MPa. Several application examples have been demonstrated, including the detection of physiological signals on human volunteers, the feedback control of intelligent robots, the grasping operation of underwater soft grippers, and the environmental wind-speed monitoring. As such, this work demonstrates a versatile and economical methodology to produce high-performance flexible sensors for various potential applications.

Noninvasive quantification of local cerebral metabolic rate of glucose for clinical application using positron emission tomography and 18F-fluoro-2-deoxy-D-glucose.

Until now, input function is still required in quantification of local cerebral metabolic rate of glucose (LCMRGlc) using positron emission tomography (PET) and (18)F-fluoro-2-deoxy-D-glucose (FDG). Some image-derived methods were developed to get input function noninvasively instead of the arterial blood sampling method, but they needed to make complicated corrections manually, so they cannot always be applied in clinic directly. Here, we propose a simple method based on the Patlak approach by using a reference tissue region and without using any information of input function. This simulation study revealed that the present method was in good agreement with Patlak method; the difference between two methods was less than 5%. The statistical errors with two methods were also obtained, and the results showed the accuracy of LCMRGlc estimated with present method was better than that with Patlak method slightly. The simulation results indicated that the calculation of LCMRGlc with present method was quite stable and independent of the choosing of reference tissue region. All of these show that the present method is a good approximation to Patlak method. The calculation with this method is very simple and easy to perform voxel by voxel; therefore, it can be widely used not only in laboratory studies but also in clinical applications although it only provides the relative rates.

A new concept of endoscopic lung cancer resection: Single-direction thoracoscopic lobectomy.

Although video-assisted thoracoscopic surgery was introduced in the early 1990s, its use in the treatment of lung cancer has been limited. We examined the effectiveness of a simplified surgical method for thoracoscopic lobectomy in patients with lung cancer from May 2006 to October 2007. This novel single-direction thoracoscopic lobectomy was characterized by incisions convenient for the placement of instruments and the lobectomy proceeded progressively in a single direction from superficial to deep structures. The procedure was completed successfully in 26 of 28 patients, with no perioperative deaths. The average operation time was 135min (range, 100-200min), average blood loss was 125mL (range 10-500mL) and average number of lymph nodes dissected was 11.8 (range, 6-23). The average postoperative hospital stay was 7.4 days (range, 5-10 days). Single-direction thoracoscopic lobectomy is a simple, safe, and effective procedure for lobe resection with clear procedural steps. It overcomes the difficulty in manipulation of incomplete lung fissures and potentially extends the indications of thoracoscopic lobectomy.

Correlation of behavior changes and BOLD signal in Alzheimer-like rat model.

To explore a potential means for the early diagnosis of Alzheimer disease, we studied the relationship of resting T2* signal and tau hyperphosphorylation/spatial memory deficit. The rat model with tau hyperphosphorylation and spatial memory deficit was established by bilateral hippocampi injection of isoproterenol (IP). Then, the correlative alteration between resting T2* signal and spatial memory retention was assessed with blood oxygenation level dependent (BOLD) functional magnetic resonance imaging (fMRI) study and Morris Water Maze test, and Western blot was employed to confirm tau hyperphosphorylation. The analysis showed following results. (1) Tau phosphorylation at Ser396/Ser404 and Ser199/Ser202 was significantly increased in IP-injected rats as detected by PHF-1 and tau-1, respectively. (2) An AD-like spatial memory retention disturbance was induced at 24 h after isoproterenol injection. (3) A sensitivity threshold of resting T2* signal intensity, which separated the IP-treated rats from vehicle control, was obtained by applying linear regression analysis, and an estimated sensitivity statistical threshold was at 32.62. These results suggest that resting T2* signal may serve as a noninvasive quantitative marker in predicting AD-like spatial memory deficits and tau hyperphosphorylation.