Issue 10

Advanced Healthcare Biomaterials

Jingan Li

Advanced Materials Letters, 2020, Volume 11, Issue 10, Pages 1-2
DOI: 10.5185/amlett.2020.101560

Biomedical field is developing towards advanced healthcare direction, including the regeneration and reconstruction of damaged tissues and organs, the restoration and enhancement of physiological functions, personalized and minimally invasive treatment, and early detection and diagnosis, etc. Traditional medical materials such as metal, macromolecule and bioceramics cannot meet the needs of rapid development of medicine. 

Piezoelectric Alternative Energy Sources as a Part of the Global Energy Concerns – Future Prospects in the Science and Market

Mariya Aleksandrova

Advanced Materials Letters, 2020, Volume 11, Issue 10, Pages 1-4
DOI: 10.5185/amlett.2020.101561

Portable and smart electronic devices are powered by batteries whose life is limited. On the other hand, in recent years the idea of renewable energy and methods of its obtaining by environmentally friendly technologies gained popularity. The conversion of energy from various sources in the surrounding environment (energy harvesting) solves the problem of battery-less power supply and satisfies the modern concepts of "clean" energy. One of the mechanisms for electrical energy generation is the piezoelectric effect, which relies on mechanical activation (vibrations, pressure, force) and the corresponding devices are piezoelectric energy harvesters. This article has overviewed the global situation, efforts, and prospects of the development of piezoelectric materials and harvesting devices in terms of research interest, industrial implementation, sectors of application and market forecasts.

Rectify the Injury-Induced Microenvironment Imbalance in Peripheral Nerve Repair

Zhiwen Yan; Yun Qian

Advanced Materials Letters, 2020, Volume 11, Issue 10, Pages 1-3
DOI: 10.5185/amlett.2020.101562

Peripheral nerve injury poses a great threat to the involved individuals’ life quality. Given the situation that the current clinical treatments have limitations, it is urgent to seek for alternative therapies. Artificial nerve guide conduits can bridge nerve gaps and the underlying mechanism is worth studying. In this perspective, we propose that a high-performance nerve guide conduit repairs peripheral nerve by rectifying the injury-induced microenvironment imbalance. And we analyse four different ways to stabilize the disturbed microenvironment: (i) nourish the distal nerve end, (ii) stabilize the immune response, (iii) rectify the energy metabolic disturbance, (iv) restore the bioelectrical signal conduction.

A Mini Review on Biodegradable Magnesium Alloy Vascular Stent

Changsheng Liu; Yachen Hou; Jingan Li

Advanced Materials Letters, 2020, Volume 11, Issue 10, Pages 1-5
DOI: 10.5185/amlett.2020.101563

Biodegradable magnesium alloy stents are a new generation of vascular stents which can open up blocked blood vessels at an early stage, then degrade and be absorbed by the body at a suitable rate after the vascular has been repaired. Mg alloys are excellent materials for vascular stents benefit from their sufficient mechanical properties and good biocompatibility. At present, Mg alloy is also used as a green material in the research of vascular stents due to its biodegradable property. In this paper, based on the research situation of degradable Mg alloy stents in recent years, the research history, degradation mechanism, structural design and basic research experiments of Mg alloy stents are reviewed.

Prospective Applications of Marine Oriented Materials in the Repair of Peripheral Nerve Injury

Yunxiao Gu; Xiaoyun Ma; Xu Wang; Cunyi Fan

Advanced Materials Letters, 2020, Volume 11, Issue 10, Pages 1-3
DOI: 10.5185/amlett.2020.101564

Peripheral nerve injury is a thorny problem for many years because it is difficult to find out appropriate drugs or materials that can maximize healing effects and minimize damages to human body. Among various methods, the use of biomaterial scaffolds on injured nerves has been favoured due to the biocompatibility, accessibility, and effectiveness. Marine oriented materials have attracted huge attention with their unique pro-regenerative potential. This article reviews the application of marine biological materials in the repair of peripheral nerve injury.

Design and Implementation of Dynamic FPAA Based Interface Circuit for Thin Film Lead-Free Piezoelectric Sensors

Ivailo M. Pandiev; Mariya P. Aleksandrova

Advanced Materials Letters, 2020, Volume 11, Issue 10, Pages 1-6
DOI: 10.5185/amlett.2020.101565

In this paper, we propose interface electronic circuit for thin film piezoelectric sensing structures. An interface electronic prototype based on dynamically programmed Field Programmable Analog Array (FPAA) is configured to implement Root-Mean-Square (RMS) to DC (RMS-to-DC) conversion process, based on direct method. The studied piezoelectric sensors are prepared by conventional microfabrication technology, involving new lead-free piezoelectric polymer-oxide composite, consisting of gallium doped zinc oxide and polyvinylidene fluoride. The devices show sensitivity to low frequency, weak mechanical loads and exhibit excellent stability at multiple vibrational cycles. It was found that a mass load of 80 g causes DC voltage of 111.8 mV with instability of less than 10 mV, which is sufficient for detection purposes.

An Аpproach for Nanostructuring of Piezoelectric Materials by Template-assisted Growth in Porous Aluminum Oxide

Tsvetozar Tsanev; Mariya Aleksandrova; Boriana Tzaneva; Valentin Videkov

Advanced Materials Letters, 2020, Volume 11, Issue 10, Pages 1-7
DOI: 10.5185/amlett.2020.101566

This paper is devoted to the approach for nanostructuring piezoelectric materials to enhance their electrical signal producing ability from a small area of mechanical activation for potential application as energy harvesting. The geometrical structuring of the piezoelectric material leads to higher piezoelectric voltage per unit volume in comparison with a non-structured thin film. Template properties of porous anodic aluminium oxide (AAO) allow this approach. AAO layers with a variety of pore diameters (from 80nm to 100nm) were produced without overheating degradation of the substrates. The thickness of the studied layer was 19 1µm. It was realized sputtering of potassium niobate deposition into AAO to a maximum penetration of piezoelectric material into the pores. The obtained final structure was observed by scanning electron microscopy and Energy Dispersive X-Ray spectroscopy. The registered piezoelectric effect reaches to 454 mV for the reanodized membrane with pores widening. In this work, we continue to explore and further development of our previous research for template-assisted growth in porous aluminium oxide.

Study of Sputtered Barium Strontium Titanate Films for Energy Harvesting Applications

Mariya Aleksandrova; Tatyana Ivanova; Sascha Koch; Frank Hamelmann; Daniela Karashanova; Kostadinka Gesheva

Advanced Materials Letters, 2020, Volume 11, Issue 10, Pages 1-7
DOI: 10.5185/amlett.2020.101567

Thin films of BaSrTiO3 (BST) were deposited by radio frequency (RF) sputtering with sputtering voltage varied between 0.5 and 0.7 kV. BaSrTiO3 films are investigated regarding their suitability for use in flexible energy harvesting devices. Analysis of the spectra and micrographs showed the piezoelectric features and the polycrystalline nature for the films grown at higher sputtering voltage. Meanwhile, the presence of an amorphous phase with a lack of characteristic bonds was found out for BaSrTiO3 films grown at the lower sputtering voltage. The electrical measurements of Al/BaSrTiO3/Al harvester on plastic substrate in the low-frequency range revealed superior piezoelectric voltage and 40% exceeding power density for the samples prepared at 0.7 kV as compared to the other thin films deposited at 0.5 kV. These results are achieved by simple architecture of single layer harvester with small size (0.4 cm 2 ) and small film thickness (0.5 µm), containing lead-free material. It was proved that the sputtered BaSrTiO3 films are suitable for thin film piezoelectric nanogenerators and their performance could be easily tuned by the sputtering voltage. Possible applications of the proposed element are low-frequency vibrational harvesting and a strain gauge.

The Effect of Bias on Properties of DLC Coatings for Artificial Joints

Ren Ying; Wang Renjie; Cheng Qiaohuan; Chen Qianqian; Xu Zhigao

Advanced Materials Letters, 2020, Volume 11, Issue 10, Pages 1-5
DOI: 10.5185/amlett.2020.101568

Diamond-like carbon (DLC) coatings, due to excellent tribological and biological properties, were used wildly to improve the wear resistance and corrosion resistance of the metal-based artificial joints. In this work, DLC coatings were deposited by a vacuum arc using the anode-cathode diameter ratio of da/dc=3/1 with the negative bias applied to the P2000 steel substrate. The relation between the substrate bias and properties of DLC coatings was investigated. The study showed that DLC coating had lower ratio of sp < sup > 2 /sp < sup > 3 and lower friction coefficient at higher bias of – 750 V. With increasing bias, the wear particle size of DCL coatings tended to move towards the distribution of smaller particles. Comparing with the uncoated P2000, P2000 coated with DLC deposited at – 750 V had better biocompatibility. It was revealed that DLC coating deposited by a vacuum arc technique in conjunction with high substrate DC biasing can improve the tribological property and biocompatibility of P2000.

Fabrication of Tens-micron-sized Functionalized Polystyrene Microspheres for Utilization in Chiral Drug Isolation

Wang Renjie; Ren Ying; Chen Qianqian; Cheng Qiaohuan; Wang Shun

Advanced Materials Letters, 2020, Volume 11, Issue 10, Pages 1-4
DOI: 10.5185/amlett.2020.101569

Functionalized polystyrene (PS) microspheres are promising materials for the isolation of the chiral drugs due to their properties, such as a large surface area, high chemical stability and tunable morphology. Considering 10-100 μm microspheres are suitable as the matrix materials of the chiral stationary phase, and there are few reports on this. Here we report a facile synthesis of the tens-micron-sized carboxylated PS microspheres by a technology between the dispersion and suspension polymerization. The relation between the reaction solutions and the size of the carboxylated PS microspheres were investigated. The study showed that, the more H2O were used in the reaction solutions, which lead the principle of the reaction more close to the suspension polymerization, the larger size of the carboxylated PS microspheres. In addition, more acrylic acid would destroy the stability of the sphere morphology. Comparing the particle size distribution and morphology, it was revealed that tens-micron-sized carboxylated PS microspheres with narrow size distribution can be fabricated with the ratio of H2O/Ethanol 30/20 and the proportion of carboxyl groups reached to ~11%.