Flexible fiber batteries for applications in smart textiles

Here we discuss two alternative approaches for building flexible batteries for applications in smart textiles. The first approach uses well-studied inorganic electrochemistry (Al-NaOCl galvanic cell) and innovative packaging in order to produce batteries in a slender and flexible fiber form that can be further weaved directly into the textiles. During fabrication process the battery electrodes are co-drawn within a microstructured polymer fiber, which is later filled with liquid electrolyte. The second approach describes Li-ion chemistry within solid polymer electrolytes that are used to build a fully solid and soft rechargeable battery that can be furthermore stitched onto a textile, or integrated as stripes during weaving process

Independence in activities after injury in humanitarian settings : assessment, change over time and associated factors

Background: Injury represents a significant burden in humanitarian settings, overwhelming the limited trauma care resources. Trauma care in these settings mainly focuses on saving lives and limbs, and not on recovery in daily activities. Rehabilitation, including physiotherapy, is often delayed and not systematic. Moreover, the lack of adequate measures of recovery of independence in activities limits the understanding of patients’ needs beyond survival. This thesis aimed at assessing recovery over the first six months after an acute orthopedic, visceral, and/or skin injury in different humanitarian settings, first revising and evaluating a measure of independence in activities, the Activity Independence Measure–Trauma (AIM-T). Methods: The three studies were conducted in eight health facilities supported or run by Médecins Sans Frontières in humanitarian settings, located in Burundi, Central African Republic, Cameroon, Iraq, Haiti, and Yemen. Study I used routine clinical data to run an inter-item correlation matrix and assess floor and ceiling effects of the initial AIM-T (AIMT1), aiming for a shortened version (AIM-T2). Then, the adequacy of the AIM-T2 was evaluated through semi-structured interviews with patients and healthcare professionals (HCPs), informing additional revisions for AIM-T3. Study II evaluated the construct validity and reliability of the AIM-T3. Study III assessed recovery at four time points (hospital admission, discharge, three and six months after injury), with different measures of recovery, including the AIM-T3. Factors associated with independence in activities (AIMT3) were identified using multivariable logistic regressions for each of three time points (i.e., discharge, three and six months). Results: In Study I (n=635), the identified redundant AIM-T1 items were removed, leading to AIM-T2. All remaining items were considered adequate by the 60 patients and 23 HCPs interviewed. Some items were revised to improve the adequacy of the content, and one item added to provide AIM-T3. In Study II (n=195), the AIM-T3 construct validity was supported, and inter-rater reliability was found to be good to excellent within a subset of 77 patients. In Study III (n=554), patients improved in all aspects of recovery across the four time points. Factors significantly associated with increased independence at one or several time points were age, type and location of injury, baseline independence and trauma care interventions, including early inpatient physiotherapy. Conclusions: The AIM-T was considered adequate to assess independence in activities after acute injury in humanitarian settings, and its validity and reliability were supported. The AIM-T has thus potential for use as an indicator of recovery in humanitarian settings. Regarding recovery, most patients still experience difficulties at six months. The association of early physiotherapy with better recovery of independence suggests that physiotherapy may be beneficial and may potentially be a modifiable factor to enhance recovery in humanitarian settings

Kinked silicon nanowires-enabled interweaving electrode configuration for lithium-ion batteries

A tri-dimensional interweaving kinked silicon nanowires (k-SiNWs) assembly, with a Ni current collector co-integrated, is evaluated as electrode configuration for lithium ion batteries. The large-scale fabrication of k-SiNWs is based on a procedure for continuous metal assisted chemical etching of Si, supported by a chemical peeling step that enables the reuse of the Si substrate. The kinks are triggered by a simple, repetitive etch-quench sequence in a HF and H2O2-based etchant. We find that the inter-locking frameworks of k-SiNWs and multi-walled carbon nanotubes exhibit beneficial mechanical properties with a foam-like behavior amplified by the kinks and a suitable porosity for a minimal electrode deformation upon Li insertion. In addition, ionic liquid electrolyte systems associated with the integrated Ni current collector repress the detrimental effects related to the Si-Li alloying reaction, enabling high cycling stability with 80% capacity retention (1695 mAh/gSi) after 100 cycles. Areal capacities of 2.42 mAh/cm2 (1276 mAh/gelectrode) can be achieved at the maximum evaluated thickness (corresponding to 1.3 mgSi/cm2). This work emphasizes the versatility of the metal assisted chemical etching for the synthesis of advanced Si nanostructures for high performance lithium ion battery electrodes

Protein adsorption on preadsorbed polyampholytic monolayers

The adsorption behaviour of five different globular proteins on pure silicon substrates and on preadsorbed polyampholytic monolayers has been investigated as a function of protein concentration. The prelayers were prepared by adsorption of the ampholytic diblock copolymer poly(methacrylic acid)-block-poly ((dimethylamino)ethyl methacrylate) (PMAA-b-PDMAEMA). This polyampholyte adsorbs in densely packed micelles directly from aqueous solution. Ellipsometry was used to determine the amount of adsorbed polyampholyte and protein. While ATR-IR spectroscopy gives information about the adsorption and desorption behaviour of the preadsorbed polyampholytic layer, the lateral structures of the dried films were investigated by scanning force microscopy (SFM). The amount of protein adsorbed was found to be strongly influenced by the preadsorbed polyampholyte compared to the adsorption on the pure silicon substrates. No displacement of the polyampholyte by the proteins was detected. In most cases the protein adsorption was reduced by the preadsorbed polyampholytic layer. The observed trends are explained by the change in electrostatic and hydrophilic characteristics of the substrates. Furthermore, the entropy of adsorption has to be taken into account.Peer reviewe

A modified Doyle-Fuller-Newman model enables the macroscale physical simulation of dual-ion batteries

Dual-ion batteries are being considered a feasible approach for electrochemical energy storage. In this battery technology both cations and anions are involved in the redox reactions, respectively, at the anode and the cathode. However, the participation of both ions in the redox reactions means that enough salt must be added in the electrolyte to ensure proper battery functioning, which present a limiting factor in battery design. Herein, a modified version of the standard pseudo-2D Doyle-Fuller-Newman model is proposed to account for the different redox reactions that occur in dual-ion batteries and simulate the variation of average salt concentration in the electrolyte during charging and discharging. The model has been validated against galvanostatic cycling and electrochemical impedance spectroscopy experimental data from dual-ion batteries based on poly(2,2,6,6-tetramethyl-1-piperidinyloxy methacrylate) (PTMA). Such a model can be helpful to design practical dual-ion batteries that respect the constraints imposed by their working mechanism and maximize the obtainable capacity and energy density