Flexible Paper-Based Li-ion Batteries: A Review

Lithium-ion (Li-ion) batteries have been fabricated in various ways to improve flexibility. Flexibility could be enhanced via active materials, separators, electrodes, and electrolytes, which could then be integrated to form flexible electronic devices with promising electrochemical properties compared to traditional non-flexible Li-ion batteries. Recent progress towards flexible Li- ion batteries fabrication, materials, and their electrochemical properties are investigated in this review. Additionally, recent developments in electronic devices utilizing flexible batteries and their future applications are explored. Portable and wearable electronics, as the primary beneficiaries of the flexible, rechargeable, and high-performance Li-ion batteries, are examined. In the end, various applications and challenges of flexible batteries in healthcare and various energy storage systems, considering practical implementation, are argued.

A Parametric Study of Mechanical Cross-Coupling in Parallel-Kinematics Piezo-Flexural Nano-Positioning Systems

Piezo-electric nano-positioning stages are being widely used in applications in which precision and accuracy in the order of nano, and high scanning speeds are paramount. This paper presents a Finite Element Analysis (FEA) of the parallel piezo-flexural nano-positioning (PPNP) stages to investigate motion interference between their different axes. Cross-coupling is one of the significant contributors to undesirable runouts in the precision positioning of PPNP actuators. Using ABAQUS/CAE 2018 software, a 3D model of a PPNP stage was developed. The model consists of a central elastic body connected to a fixed frame through four flexural hinges. A cylindrical stack of multiple piezoelectric disks is placed between the moving central body and the fixed frame. Extensive simulations were carried out for three different friction coefficients in the piezoelectric disks’ contact surfaces, different frame materials, and different geometrical configurations of the stage and the hinges. As a result, it was observed that the primary root cause of the mechanical cross-coupling effect could be realized in the combination of the slip and rotation of the piezoelectric disks due to their frictional behavior with the stage moving in the tangential direction, concurrent with changes in the geometry of the stage.

An Assessment of the Relationship between Nonunion and Device Failure Following the Treatment of Intertrochanteric Fracture, by Dynamic Hip Screw (DHS) Using Arbeitsgemeinschaft fur Osteosynthesfrogen/Orthopedic Trauma Association (AO/OTA) and Dorr Classification

Background: Intertrochanteric fractures are of intense interest globally. They are the most frequently operated fracture type, have the highest postoperative fatality rate of surgically treated fractures, and have become a serious health resource issue due to the high cost of care required after injury. A number of problems exist when determining the best option for treatment for intertrochanteric fractures. The classification systems do not work well enough for preoperative planning and the reduction criteria have not been well defined. Methods: All patients who presented to Firoozgar Hospital, Tehran with intertrochanteric fracture, between March 20th 2013 and December 21st 2015, underwent DHS implementation, after 6-month follow-up period. Demographic data, preoperative radiographic fracture, bone quality typing (AO/OTA and Dorr classification), American Society of Anesthesiologists (ASA) score and evaluation of their correlation with the complication of fixation including nonunion and device failure were recorded and analyzed. Result: 101 patients including 54 males (53.5%) and 47 females (46.5%) underwent DHS implementation. Mean population age was 73.06 ± 16.36 years with an age range of 30 to 94 years;the most frequent age period was 76 - 85 years, injured by low-energy trauma mechanism and 23.8% patients were injured in a high-energy trauma. 56 patients completed the 6-month follow-up evaluation which ranged from 1 to 80 weeks. According to AO/OTA classification, the most common type among the patient population was A2, 27 patients (51.5%);while the most common group from Dorr classification turned to be group B (39.6%). Classification by ASA score revealed Class II to be most frequent among the patient population (56.4%). Nonunion was seen in eight of patients (14.3%). Three patients (5.4%) had device failure, two cases showed side plate breakage, and another one had screw cut out. There was no significant relationship between AO/OTA classification with the both complications i.e. the development of device failure (P = 0.85) and nonunion (P = 0.99). Non-significant correlation was found between Dorr classification with device failure (P = 0.06) and nonunion (P = 0.11). Conclusion: Regarding recent studies, more effective factor on the outcome is patient’s medical condition before surgery compared to the radiographic findings including AO/OTA and Dorr classification.