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Supplemental Digital Content is Available in the Text. Acupuncture treatment for 6-month period altered DNA methylation patterns, particularly in the prefrontal cortex, in a mouse model of chronic neuropathic pain., Chronic pain reduces life quality and is an important clinical problem associated with emotional and cognitive dysfunction. Epigenetic regulation of DNA methylation is involved in the induction of abnormal behaviors and pathological gene expression. We examined whether acupuncture can restore epigenetic changes caused by chronic pain, and identified the underlying mechanisms in neuropathic pain mice. Acupuncture treatment for 6 months (3 days/week) improved mechanical/cold allodynia and the emotional/cognitive dysfunction caused by left partial sciatic nerve ligation (PSNL)-induced neuropathic pain. The effects of acupuncture were associated with global DNA methylation recovery in the prefrontal cortex (PFC). Analysis of DNA methylation patterns in PFC indicated that 1364 overlapping genes among 4442 and 4416 methylated genes in the PSNL vs sham and PSNL vs acupuncture points groups, respectively, were highly associated with the DNA methylation process. Acupuncture restored the reduced expression of 5-methylcytosine, methyl-cytosine-phospho-guanine binding protein 2, and DNA methyltransferase family enzymes induced by PSNL in PFC. Methylation levels of Nr4a1 and Chkb associated with mitochondrial dysfunction were decreased in PFC of the PSNL mice, and increased by acupuncture. By contrast, high expression of Nr4a1 and Chkb mRNA in PSNL mice decreased after acupuncture. We also found that acupuncture inhibited the expression of Ras pathway-related genes such as Rasgrp1 and Rassf1. Finally, the expression of Nr4a1, Rasgrp1, Rassf1, and Chkb mRNA increased in the neuronal cells treated with Mecp2 small interfering RNA. These results suggest that acupuncture can relieve chronic pain-induced comorbid conditions by altering DNA methylation of Nr4a1, Rasgrp1, Rassf1, and Chkb in the PFC.

The piezoelectric energy generation properties of transparent flexible devices (TFD) based on PbZr 0.52 Ti 0.48 O 3 (PZT) films, which were fabricated by laser lift-off (LLO) process, were studied for a piezoelectric energy harvester. Through the introduction of indium-tin-oxide (ITO) and polyethylene terephthalate (PET) substrates, TFDs were implemented, respectively. The TFDs based on PZT films generated an AC-type output signal and output power of 8.4 nW/cm 2 , at periodically bending and releasing motion. In addition, inverted output signals were observed when the manufactured TFDs were connected to the measuring equipment in reverse and were bended to the reverse direction, demonstrating that the generating signals originated from the piezoelectric effect of TFDs. The experimental results clearly showed that the TFDs based PZT film have potential for use in next generation of electronic devices applications such as flexible devices, transparent electronics, and energy harvester.

The ferroelectric properties of flexible devices based on 0.05Pb(Al 0.5 Nb 0.5 )O 3 –0.95Pb(Zr 0.52 Ti 0.48 )O 3 + 0.7 wt.%Nb 2 O 5 + 0.5 wt.%MnO 2 (PAN-PZT) thin films, which were fabricated using a laser lift-off (LLO) process, were investigated. The flexible devices based on PAN-PZT thin films were coated with a sacrificial layer, which prevented or minimized damage during LLO process. The structural and electrical properties of the PAN-PZT thin films before and after LLO process demonstrated that the crystallographic and ferroelectric properties of the device were retained after LLO process. Flexible devices based on PAN-PZT thin films coated with a sacrificial layer may be fabricated using the LLO process for the production of flexible electronic devices.

(Ba,Sr)TiO 3 (BST) thin film with a perovskite structure has a potential for the practical applications in various functional devices. Normally, the BST thin films derived from sol–gel and sputtering are amorphous or partially crystalline when processed below 700 °C. For the purpose of integrating BST thin film directly into system-on-package (SoP), it is necessary to process the BST film below 350 °C. The electrical properties of low-temperature crystallized BST film were studied in this paper. The BST thin films have been crystallized at 300 °C by excimer laser annealing (ELA). The BST films were exhibited in a single perovskite phase and have well-defined electrical properties such as high dielectric constant, low dielectric loss and low leakage current density. As a result, we demonstrated crystallized BST thin film which has permittivity of 143, dielectric loss of 0.028 and leakage current density of 0.9 μA/cm 2 below 300 °C.

Bilayer TiOx (oxygen rich, region 1)/TiOy (oxygen poor, region 2) homojunctions were evaluated as resistive switching elements where the TiOx layers were designed with various oxygen contents. Depending on the oxygen ion content, controllable memory windows were observed by changing the off-state (high-resistance state), while the on-state (low resistance) was left with very little change. The cause of the variable memory windows in resistive switching phenomena appears to be the increasing amounts of movable oxygen ions between the TiOx and TiOy layers. In addition, the X-ray photoelectron spectroscopy measurements of the initial, low resistance, and high-resistance states in the homojunctions demonstrated the possible change of metallic and insulating Ti sub-oxide phases at the interfaces and oxygen ion rich region due to the migration of oxygen ions.

The bipolar resistive switching characteristics in polycrystalline TiO2 thin films after regular forming process were studied using two different top or bottom TiN electrodes (Sample A: top TiN/TiO2/Pt, Sample B: Pt/TiO2/TiN bottom). The sample A and B clearly showed two different switching directions of counter-clockwise (CCW) and clockwise (CW) bipolar switching behaviors, respectively, depending on the relative position of the TiN electrode. These switching characteristics in both samples could be understood by considering the forming and rupture of the conducting path due to the migration of oxygen ions between the TiO2 layer and the TiN electrode, which acts like the oxygen reservoir. In addition, both samples clearly display high reliable memory switching characteristics, such as stable switching speed (μs), endurance behaviors (>104), and long retention times (>104 s).

We systematically investigated the resistive switching properties of thin TiO₂ films on Pt/Ti/SiO₂/Si substrates that were embedded with a Co ultra thin layer. An in-situ sputtering technique was used to grow both films without breaking the chamber vacuum. A stable bipolar switching in the current-voltage curve was clearly observed in TiO₂ films with an embedded Co ultra thin layer, addressing the high and low resistive state under a bias voltage sweep. We propose that the underlying origin involved in the bipolar switching may be attributed to the interface redox reaction between the Co and TiO₂ layers. The improved reproducible switching properties of our novel structures under forward and reverse bias stresses demonstrated the possibility of future non-volatile memory elements in a simple capacitive-like structure.

The single-layer 400 μm × 200 μm sized Ba0.6Sr0.4TiO3 thin-film embedded chip capacitors with two external electrodes fabricated on the surface of the chip capacitors have been demonstrated. The structure of the external electrodes placed on the same surface allows the reduction of connection length, resulting in low parasitic loss and noise of elecronic devices. The fabricated chip capacitors exhibited excellent electrical properties such as high capacitance density and dielectric constant (1687 nF/cm2 and 452) and a low dielectric loss of 0.052 at 1 kHz, respectively. In addition, the chip capacitors exhibited the superior temperature stability of X5R (ΔC/C = ±15% at -55°C to +85°C) characteristics. Such a low leakage current density of ~ 0.15 μA/cm2 at 3 V and a high breakdown voltage of 19.75 V were obtained as well. In conclusion, the chip capacitors are suggested as a candidate for the applications of embedded passive components.

Resistance switching phenomena in an amorphous Ni-Ti-O film were investigated. Very clear bipolar resistive switching characteristics were observed with good reproducibility. Stable retention and on/off pulse switching operation was demonstrated. An analysis of x-ray photoelectron spectroscopy of the Ni-Ti-O film provided a clue that the observed unusual bipolar resistance switching in the film is due to a microscopic change in the Ni-O and Ti-O binding states at the Ni-Ti-O film/electrode interface.

We demonstrated a way to fabricate the crystalline Ba0.6Sr0.4TiO3 (BST) thin films using excimer laser annealing technique on the amorphous BST thin films fabricated by sol-gel process. The grain size of the laser-annealed films is larger than that of the conventionally thermal-annealed films. However, an uncrystallized, amorphous layer was observed near the film/substrate interface due to the limited laser absorption depth. The uncrystallized layer has a critical influence on out-of-plane dielectric property of BST films. The significant difference of the relative dielectric permittivity (er) between in-plane (1383) and out-of-plane (184) directions is observed.

Reversible counter-clockwise and clockwise resistive switching in a TiN/TiO2/TiN structure was studied by different polarities of bias voltage. The nature of the bipolar switching phenomenon is related to the creation and annihilation of filament paths caused by redox reactions at locally confined interfaces between the TiO2 layer and TiN electrode. The analysis of electron energy loss spectroscopy (EELS) confirmed the formation of interfacial TiOxN1−x layer between the TiO2 and TiN bottom electrode. The TiOxN1−x layer reduces current levels of ON and OFF states by partially blocking oxygen ion drift to the TiN bottom electrode.

TiO2 (oxygen rich, region 1)/TiO2−x (oxygen poor, region 2) multilayer homojunctions were studied as alternative resistive switching structures for both high and low resistance transitions. Stable bipolar resistive switching characteristics, including stable switching speeds (microseconds) and endurance behaviors, as well as long retention times (>104 s) were demonstrated. The nature of the resistive switching phenomenon in multilayer structures seems to be a combination of the conduction path and the redox reaction, resulting from the oxygen ions drifting between the oxygen rich and poor regions of the multilayer structures. A possible conduction sketch for bipolar switching behaviors is also discussed.

Stable bipolar resistive switching was demonstrated in polycrystalline TiO2 films involving two different top and bottom Al electrodes of two different structures (Al/TiO2/Pt and Pt/TiO2/Al) after a forming process. With an Al electrode, the transition to bipolar resistive switching was clearly observed, together with counterclockwise and clockwise switching directions, which depended on the position of the Al electrode. The transition from unipolar to bipolar resistive switching seems to be attributable to the redox reaction and trap/detrap at the interfaces between the Al electrode and TiO2 layer due to the migration of oxygen ions and electrons. However, current level analysis of devices reveals that the forming process method basically leads to the formation of conducting paths inside the TiO2 layers. The electrical device properties of the two different structures, the effects of compliance currents, and the operation voltages are also analyzed.

An in situ direct radiation annealing (IDRA) technique on the AlOx insulating barrier was performed to enhance the thermal stability of magnetic tunneling junctions (MTJs). Our method was found to improve the dielectric and structural properties of AlOx insulating barrier in MTJs. After the proper IDRA process, the conventional ex situ annealing process exhibited an additional enhancement of thermal stability by significantly reducing the interdiffusion process between Co80Fe20 electrode and AlOx insulating barriers. Experimentally observed tunneling magnetoresistance of MTJs after the IDRA process showed about 55% up to 350°C. Finally, a surface-plamon resonance spectroscope measurement observed that the dielectric constant of insulating barriers was increased from 2.7 to 3.2 after the IDRA process.