Random-start ovarian stimulation in an oocyte donation programme: a large, single-centre, experience.

RESEARCH QUESTION: Do live birth rates differ between recipients matched with donors using conventional ovarian stimulation compared with those using random-start protocols? DESIGN: Retrospective analysis of 891 ovarian stimulations in egg donors (January-December 2018) and clinical outcomes in matched recipients (n = 935). Donors commenced ovarian stimulation on day 1-3 of the menstrual cycle (n = 223) or in the mid/late-follicular (n = 388) or luteal phase (n = 280) under a conventional antagonist protocol. Live birth rate of matched recipients was the main outcome. RESULTS: Duration of stimulation and total gonadotrophin dose were comparable between conventional versus random-start groups. The number of collected eggs were similar (17.6 ± 8.8 versus 17.2 ± 8.5, P = 0.6, respectively). Sub-group analysis showed that stimulation length (10.2 ± 1.8 versus 9.8 ± 1.7 versus 10.4 ± 1.7, P < 0.001) and gonadotrophin consumption (2041.5 ± 645.3 versus 2003.2 ± 647.3 versus 2158.2 ± 685.7 IU, P = 0.01) differed significantly between the conventional, mid/late follicular and luteal phase groups, respectively. In matched recipients receiving fresh oocytes and undergoing fresh embryo transfer, the biochemical pregnancy (63.8% and 63.3%; P = 0.9), clinical pregnancy (54.6% and 56.1%; P = 0.8) and live birth rates (47.7% and 46.6%; P = 0.7) per embryo-transfer were similar between conventional versus random groups. Similar results were obtained in recipients receiving vitrified eggs. Euploidy rate was also comparable. CONCLUSIONS: No notable variations were found in clinical outcomes using oocytes obtained from random-start protocols and those proceeding from conventional ovarian stimulation in oocyte donation treatments. Luteal-phase stimulation seems to require longer stimulation and higher FSH consumption. Random-start stimulation strategy does not impair the potential of the oocyte yield or clinical outcomes in oocyte donation cycles.

Does mRNA COVID-19 vaccination in oocyte donors impact ovarian stimulation parameters or IVF outcomes for recipients?

RESEARCH QUESTION: What is the effect of mRNA severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination in young oocyte donors in terms of ovarian response to stimulation, fertilization rate, embryo development and clinical outcomes in recipients? DESIGN: This retrospective, multicentre cohort study evaluated 115 oocyte donors who had undergone at least two ovarian stimulation protocols (before and after complete SARS-CoV-2 vaccination) between November 2021 and February 2022. Comparisons were made of the primary outcomes of days of stimulation, total dose of gonadotrophins and laboratory performance in ovarian stimulation in oocyte donors before and after vaccination. A total of 136 cycles in matched recipients were analysed as secondary outcomes and, from those, 110 women received a fresh single-embryo transfer, with analysis of biochemical ß-human chorionic gonadotrophin concentrations and rates of clinical pregnancy with heartbeat. RESULTS: Longer stimulation was required in the post-vaccination than pre-vaccination group (10.31 ± 1.5 versus 9.51 ± 1.5 days; P < 0.001) along with higher gonadotrophin consumption (2453.5 ± 740 versus 2235.5 ± 615 IU; P < 0.001) with a similar starting dose of gonadotrophins in both groups. More oocytes were retrieved in the post-vaccination group (16.62 ± 7.1 versus 15.38 ± 7.0; P = 0.02). However, the number of metaphase II (MII) oocytes was similar between groups (pre-vaccination 12.61 ± 5.9 versus post-vaccination 13.01 ± 6.6; P = 0.39) and the ratio of MII/retrieved oocytes favoured the pre-vaccination group (0.83 ± 0.1 versus 0.77 ± 0.2 post-vaccination; P = 0.019). In recipients with a similar number of provided oocytes, the fertilization rate, total number of obtained blastocysts, number of top-quality blastocysts, and rates of biochemical pregnancy and clinical pregnancy with heartbeat were not significantly different between groups. CONCLUSIONS: This study shows no adverse influence of mRNA SARS-CoV-2 vaccination on ovarian response in a young population.

FSH receptor genotype and its influence on the results of donor ovarian stimulation using corifollitropin alfa.

RESEARCH QUESTION: Does the FSH receptor (FSHR) genotype influence the results of donor ovarian stimulation using corifollitropin alfa? DESIGN: A prospective cohort study was performed including 152 oocyte donor ovarian stimulations: group 1 (n = 80) using a single dose of 150 µg of corifollitropin alpha; and group 2 (n = 72) using in addition to corifollitropin alpha, continued stimulation using recombinant FSH 225 IU daily. Allelic discrimination was used to genotype the FSHR p.N680S polymorphism. Linear regression analysis was performed to study the differences between groups. RESULTS: No differences in clinical characteristics between genotypes were reported. Overall, the results of ovarian stimulation were better in oocyte donors with SN and NN genotypes compared with SS in terms of the number of retrieved oocytes (15.78 versus 10.83; P = 0.008) and retrieved metaphase II (MII) oocytes (12.34 versus 9.00; P = 0.032). Corresponding differences were also observed in group 1 for the number of retrieved oocytes (13.83 versus 7.50, P = 0.018) and retrieved MII oocytes (10.24 versus 5.42; P = 0.038). However, in group 2 no significant differences were found for oocytes retrieved (17.55 versus 13.06, P = 0.064) or MII oocytes (14.25 versus 11.39; P = 0.12). CONCLUSIONS: This study suggests that ovarian stimulation protocols with corifollitropin alfa in women with the SS genotypes could be associated with fewer oocytes and MII oocytes retrieved. Despite the fact that corifollitropin alfa has a longer half-life, the results for the SS genotype do not match those for the other genotypes, so other factors must be involved. Therefore, to tailor treatments, it would be advisable to genotype women at p.N680S of the FSHR.

Evaluation of the tert-butyl group as a probe for NMR studies of macromolecular complexes.

The development of methyl transverse relaxation optimized spectroscopy has greatly facilitated the study of macromolecular assemblies by solution NMR spectroscopy. However, limited sample solubility and stability has hindered application of this technique to ongoing studies of complexes formed on membranes by the neuronal SNAREs that mediate neurotransmitter release and synaptotagmin-1, the Ca2+ sensor that triggers release. Since the 1H NMR signal of a tBu group attached to a large protein or complex can be observed with high sensitivity if the group retains high mobility, we have explored the use of this strategy to analyze presynaptic complexes involved in neurotransmitter release. For this purpose, we attached tBu groups at single cysteines of fragments of synaptotagmin-1, complexin-1 and the neuronal SNAREs by reaction with 5-(tert-butyldisulfaneyl)-2-nitrobenzoic acid (BDSNB), tBu iodoacetamide or tBu acrylate. The tBu resonances of the tagged proteins were generally sharp and intense, although tBu groups attached with BDSNB had a tendency to exhibit somewhat broader resonances that likely result because of the shorter linkage between the tBu and the tagged cysteine. Incorporation of the tagged proteins into complexes on nanodiscs led to severe broadening of the tBu resonances in some cases. However, sharp tBu resonances could readily be observed for some complexes of more than 200 kDa at low micromolar concentrations. Our results show that tagging of proteins with tBu groups provides a powerful approach to study large biomolecular assemblies of limited stability and/or solubility that may be applicable even at nanomolar concentrations.

Luteal phase stimulation versus follicular phase stimulation in poor ovarian responders: results of a randomized controlled trial.

BACKGROUND: In young women with poor ovarian response, luteal-phase ovarian stimulation (LPOS) is a potential method for collecting competent oocytes. The aim of this study was to assess the efficacy of LPOS compared with follicular phase ovarian stimulation (FPOS) in young women with poor ovarian response (POR). METHODS: This single-center, prospective, randomized pilot study compared LPOS and FPOS in women with POR fulfilling Bologna criteria who underwent in vitro fertilization at the Instituto Bernabeu. The primary outcome was the number of metaphase II (MII) oocytes obtained by follicular puncture. RESULTS: Sixty women were included in the study, with 27 women completing LPOS and 30 undergoing FPOS. There was no statistically significant difference in the number of MII oocytes obtained between the LPOS group and the FPOS group (2.1 ± 2.0 vs. 2.6 ± 2.2, p = 0.31). Length of stimulation was also similar in both groups (8.35 ± 2.8 vs. 8.15 ± 4.1 days, p = 0.69). Similarly, there was no significant difference in the follicle-stimulating hormone total dose, number of cumulus-oocyte complexes, survival rate, fertilization rate, or cancellation rate between groups. A significantly higher Ovarian Sensitivity Index was observed in the LPOS group versus the FPOS group (0.96 vs. 0.57, p = 0.037). CONCLUSION: LPOS was comparable with FPOS in terms of efficacy and may improve ovarian responsiveness in young women with POR. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT02625532; EudraCT identifier: 2015-003856-31.

Ovarian hyperstimulation syndrome following GnRH agonist trigger for final follicular maturation in a patient undergoing random start ovarian stimulation for egg-donation cycle with an inadvertent concomitant early pregnancy.

We report the first case of OHSS following GnRH agonist trigger for final follicular maturation in random start ovarian stimulation for egg-donation cycles during inadvertent concomitant early pregnancy. As an additional note, the sustained activity exerted by the increasing endogenous hCG production seemed to be responsible for the suboptimal performance in terms of oocyte yield in the current case. OHSS can occur in random-start stimulations protocols even after the use of a GnRH agonist for triggering in case of concomitant unnoticed early pregnancy especially if stimulation is commenced in the periovulatory/luteal phase. The present case report introduces a note of extreme caution when proceeding with this protocol in an otherwise fertile population (egg-donors, elective or oncologic oocyte cryopreservation).

The relevance of the individual screening for genetic variants in predicting ovarian response.

OBJECTIVE: To investigate if polymorphisms of some genes involved in folliculogenesis predict ovarian response. METHODS: This prospective randomized study includes 124 egg donors genotyped for six SNPs ESR1 (rs2234693), AMHR2 (rs2002555), GDF-9 (rs10491279 and rs254286), AMH (rs10407022) and LHCBR (rs229327) genes and four STRs in ESR1 rs3138774), SHBG (rs6761), CYP19A1 (rs60271534) and AR genes (CAG repeats in exon 1). All donors followed standard ovarian stimulation protocol using a daily dose of 225 UI. The genotypes obtained were compared with the ovarian stimulation outcome. RESULTS: Regarding the number of retrieved oocytes, we found statistical differences for the ESR1 SNP and STR (19.3 ± 8.9 for TT vs 15.3 ± 6.2 for CC/CT, P = 0.027; 19.1 ± 8.3 for <17repeats vs 14.7 ± 6.2 for >17repeats, P = 0.020). Moreover, women carrying TT in the ESR1 at position c.-397T>C with ESR1 (TA)n=17 retrieved the highest number of oocytes (20.4 ± 9.3) (P = 0.001). Concerning AMHR2, we observed an association with the length of stimulation (9.1 ± 1.4 d for AA vs 9.7 ± 1.3 d for AG/GG, P = 0.021) and gonadotropin received (2050 ± 319 for AA vs 2188 ± 299 for AG/GG, P = 0.017). No significant differences were observed for the other polymorphisms (P > 0.05). CONCLUSION: The polymorphisms in ESR1 and AMHR2 genes showed a clear association with the number of retrieved oocytes and the stimulation data, respectively. Our results suggest that polymorphisms in the genes for key reproductive hormones receptors could be used to predict the ovarian response and to personalize the stimulation prior the treatment.

Comparison of two closed carriers for vitrification of human blastocysts in a donor program.

The survival of human blastocysts to vitrification with two different carriers is compared. Both vitrification carriers used in this study are in the category of closed carriers, as they completely isolate the samples from direct contact with liquid nitrogen or its vapours during cooling and storage, until warming. This characteristic is appealing because it reduces or eliminates the theoretical risk of cross-contamination during that period of time. The two closed vitrification systems used present very different design and features: in the High Security Vitrification device, the carrier straw containing the embryos is encapsulated inside an external straw before plunging in liquid nitrogen, resulting in thermal insulation during cooling. On the other hand, in the SafeSpeed carrier embryos are loaded in a thin-walled, narrow capillary designed to maximize the thermal transference. Both closed carriers achieved comparable outcomes in terms of survival of blastocysts to the vitrification process, with 97.5% vs. 96.1% survival with HSV and SafeSpeed, respectively. In conclusion, the cooling and warming rates at which these carriers operate, in combination with the cytosolic solute concentration in the cells of the cryopreserved blastocysts attained after a cryoprotectant-loading protocol, result in successful vitrification of human blastocysts for human assisted reproduction.

Metabolites involved in cellular communication among human cumulus-oocyte-complex and sperm during in vitro fertilization.

BACKGROUND: Fertilization is a key physiological process for the preservation of the species. Consequently, different mechanisms affecting the sperm and the oocyte have been developed to ensure a successful fertilization. Thus, sperm acrosome reaction is necessary for the egg coat penetration and sperm-oolema fusion. Several molecules are able to induce the sperm acrosome reaction; however, this process should be produced coordinately in time and in the space to allow the success of fertilization between gametes. The goal of this study was to analyze the metabolites secreted by cumulus-oocyte-complex (COC) to find out new components that could contribute to the induction of the human sperm acrosome reaction and other physiological processes at the time of gamete interaction and fertilization. METHODS: For the metabolomic analysis, eighteen aliquots of medium were used in each group, containing: a) only COC before insemination and after 3 h of incubation; b) COC and capacitated spermatozoa after insemination and incubated for 16-20 hours; c) only capacitated sperm after 16-20 h in culture and d) only fertilization medium as control. Six patients undergoing assisted reproduction whose male partners provided normozoospermic samples were included in the study. Seventy-two COC were inseminated. RESULTS: The metabolites identified were monoacylglycerol (MAG), lysophosphatidylcholine (LPC) and phytosphingosine (PHS). Analysis by PCR and in silico of the gene expression strongly suggests that the cumulus cells contribute to the formation of the PHS and LPC. CONCLUSIONS: LPC and PHS are secreted by cumulus cells during in vitro fertilization and they could be involved in the induction of human acrosome reaction (AR). The identification of new molecules with a paracrine effect on oocytes, cumulus cells and spermatozoa will provide a better understanding of gamete interaction.

Smart TV-Smartphone Multiscreen Interactive Middleware for Public Displays.

A new generation of public displays demands high interactive and multiscreen features to enrich people's experience in new pervasive environments. Traditionally, research on public display interaction has involved mobile devices as the main characters during the use of personal area network technologies such as Bluetooth or NFC. However, the emergent Smart TV model arises as an interesting alternative for the implementation of a new generation of public displays. This is due to its intrinsic connection capabilities with surrounding devices like smartphones or tablets. Nonetheless, the different approaches proposed by the most important vendors are still underdeveloped to support multiscreen and interaction capabilities for modern public displays, because most of them are intended for domestic environments. This research proposes multiscreen interactive middleware for public displays, which was developed from the principles of a loosely coupled interaction model, simplicity, stability, concurrency, low latency, and the usage of open standards and technologies. Moreover, a validation prototype is proposed in one of the most interesting public display scenarios: the advertising.

Lateral window sinus augmentation: complications and outcomes of 101 consecutive procedures.

PURPOSE: To report the complications experienced and the outcomes of simultaneous or staged dental implants placed during 101 consecutive sinus augmentation procedures through the lateral window approach. PATIENTS AND METHODS: Sixty-eight consecutive patients underwent a total of 101 sinus augmentations. Thirty-nine patients were operated on unilaterally and 29 bilaterally. A total of 141 implants were installed, 65 simultaneously and 76 in a second stage. RESULTS: In 13 of the 101 sinuses, the Schneiderian membrane was perforated. Three patients developed maxillary sinusitis. Two patients suffered perioperative hemorrhages. One patient had a wound dehiscence, and 3 patients developed graft infections. Of the 141 implants, 121 integrated and 14 failed. There was a statistical difference between the losses of implants placed simultaneously versus nonsimultaneously (P = 0.003). The overall postloading success rate for dental implants reached 90% after a follow-up period between 12 and 120 months. CONCLUSION: The lateral window approach is associated with a high rate of success. Yet, some complications can influence the outcome of clinical treatment. Simultaneous placement of implants during sinus augmentation significantly affects their chance of success.

Androgen receptor CAG repeat length is associated with ovarian reserve but not with ovarian response.

The human androgen receptor (AR) gene contains a highly polymorphic CAG repeat sequence within exon 1. In-vitro studies have shown a relationship between CAG repeats in the AR gene and its transactivation potential. This variation in length may play a role in anovulatory infertility. The objective of this study was to investigate whether CAG polymorphism of the AR gene has a predictive value for ovarian reserve, response and cycle outcome in an egg donor programme. CAG length of the AR gene was determined in 147 oocyte donors. All donors underwent ovarian stimulation with a gonadotrophin-releasing hormone antagonist protocol (n = 355). No differences were reported in days of stimulation, gonadotrophin doses, and number of oocytes retrieved. Clinical outcomes were not affected by the CAG repeat length of the AR gene; the primary end-point, antral follicle count, was significantly affected (P < 0.05). In conclusion, in a population of fertile egg donors AR gene CAG polymorphism does not affect ovarian response to gonadotrophins. Antral follicle count was associated with the CAG polymorphism genotype. This suggests that genetic factors may increase susceptibility to poor ovarian reserve, and that AR gene genotype could play a role in the natural ovarian ageing process.

A modified transoral approach for carotid artery type Eagle syndrome: technique and outcomes.

OBJECTIVE: This article aimed to summarize our clinical experience with a standardized tonsil-sparing transoral surgical approach used for treatment of styloid process-carotid artery Eagle's syndrome. METHODS: Eleven consecutive patients, from 2007 to 2013, underwent surgical treatment to remove elongated styloid apophyses transorally. Outcomes were assessed in terms of intraoperative and postoperative complications and patients' evolution. RESULTS: No patient experienced any intraoperative or postoperative complications. All patients have been followed up to present and 10 of them have shown complete relief of the symptoms and improvement of functional ability. CONCLUSION: The tonsil-sparing transoral surgical approach described is suitable for treating patients with elongated styloid apophyses.

Desmoplastic fibroma of the mandible: report of a misdiagnosed case.

Several odontogenic and non-odontogenic tumors and related lesions affecting the jaws share clinical presentation and imaging appearance. However, all cases have to be approached and treated on an individual basis, based on a reliable anatomic pathology diagnosis. The present paper describes a case of a desmoplastic fibroma, which was misdiagnosed as an odontogenic keratocyst, and spotlights the potential benefit and conclusive role of a second opinion in oral and maxillofacial pathology diagnosis. A brief review of the literature is also provided.

Chronic venous disease: What if everything started with early care? A discussion with experts.

Chronic venous disease (CVD) is an umbrella term for a group of morphological and functional disorders of the venous system. Clinical signs of CVD may range from telangiectasia and reticular veins to active venous ulcers; therefore, earlier diagnosis and management of CVD may delay disease progression and reduce the burden of CVD on patients, caregivers, and healthcare systems. In this podcast discussion, Professor Andrew Nicolaides, Professor Stavros Kakkos, and Dr Gerardo Estrada-Guerrero share the key highlights from their symposium at the 2023 European Venous Forum. This symposium, titled "Chronic venous disease: what if everything started with early care?", discussed the clinical significance of "functional CVD," evidence and risk factors for CVD progression, and real-world strategies to facilitate earlier diagnosis and management of CVD. Together, these topics highlight the importance of early care to improve long-term outcomes for people with CVD.

Chronic venous disease (CVD) occurs when the blood vessels that carry blood back to the heart are damaged. In the early stages of CVD, people may have visible or swollen veins in their legs and feet, and may feel pain, heaviness, burning, itching, and cramping. Without treatment, people with CVD may develop open sores (ulcers) that are hard to heal and could get infected, so it is important that CVD is diagnosed and treated early. In this podcast, three doctors who specialize in CVD answer questions about a presentation they gave at a recent medical conference. In their presentation, the doctors talked about people who experience feelings of CVD but without any visible signs, and looked at programs that might help doctors diagnose CVD earlier. The doctors agree that it is important to diagnose and treat CVD early, so that people can avoid the long-term effects of this disease.

Exome sequencing in genuine empty follicle syndrome: Novel candidate genes.

OBJECTIVE(S): Empty follicle syndrome (EFS) is a condition in which no oocytes are retrieved in an IVF cycle despite apparently normal follicular development and meticulous follicular aspiration following ovulation induction. The EFS is called genuine (gEFS) when the trigger administration is correct. The existence of gEFS is a subject of controversy, and it is quite rare with an undetermined etiology. Genetic defects in specific genes have been demonstrated to be responsible for this condition in some patients. Our objective was to identify novel genetic variants associated with gEFS. STUDY DESIGN: We conducted a prospective observational study including 1,689 egg donors from July 2017 to February 2023. WES were performed in patients suffering gEFS. RESULTS: Only 7 patients (0.41 %) exhibited gEFS after two ovarian stimulation cycles and we subsequently performed whole exome sequencing (WES) on these patients. Following stringent filtering, we identified 6 variants in 5 affected patients as pathogenic in new candidate genes which have not been previously associated with gEFS before, but which are involved in important biological processes related to folliculogenesis. These genetic variants included c.603_618del in HMMR, c.1025_1028del in LMNB1, c.1091-1G > A in TDG, c.607C > T in HABP2, c.100 + 2 T > C in HAPLN1 and c.3592_3593del in JAG2. CONCLUSION: As a conclusion, we identified new candidate genes related to gEFS that expand the mutational spectrum of genes related to gEFS.This study show that WES might be an efficient tool to identify the genetic etiology of gEFS and provide further understanding of the pathogenic mechanism of gEFS.

Racial Disparities in Outcomes Following Surgical Fixation of Traumatic Thoracolumbar Fractures: A National Database Analysis.

OBJECTIVE: This study aims to assess race as an independent risk factor for postoperative complications after surgical fixation of traumatic thoracolumbar fractures for African American and Asian American patients compared with White patients. METHODS: The 2011-2021 American College of Surgeons - National Surgical Quality Improvement Program (ACS-NSQIP) dataset was used to identify patients undergoing fusion surgeries for thoracolumbar spine fractures. Patient comorbidity burden was assessed using a modified 5-item frailty index score (mFI-5). Chi-squared and ANOVA tests were used to compare baseline clinical characteristics between groups. Multivariate analysis was performed to compare African American and Asian American patients with White patients controlling for age, BMI, and American Society of Anesthesiologists (ASA) score. RESULTS: African American patients experienced longer operative times compared to Asian American and White patients (3.74 ± 1.87 hours vs. 3.04 ± 1.71 hours and 3.48 ± 1.81 hours, P < 0.001). African American and Asian American patients demonstrated higher comorbidity burden with mFI-5>2 compared to White patients (30.7% and 25.6% vs. 19.9%, P < 0.001). African American and Asian American patients had a higher risk of postoperative complications than White patients (22.4% and 20% vs. 19.7%, P < 0.001). African American race was an independent risk factor of postoperative 30-day morbidity (OR 1.19, CI 1.11-1.28, P < 0.001). CONCLUSIONS: African American and Asian American patients undergoing thoracolumbar fusion surgeries exhibit disproportionate comorbidity burden, longer LOS, and greater postoperative complications compared with White patients. Furthermore, the African American race was associated with an increased rate of 30-day postoperative complications.

Impact of Group vs Individual Embryo Culture Strategies on Blastocyst and Clinical Outcomes.

Embryo culture is one of the most important steps in an assisted reproduction laboratory. Embryos can be cultured individually, one embryo per media drop, or in groups, culturing several embryos in the same media drop. Due to the controversy generated on this subject, we wondered which embryo culture method would have the best results in terms of quality and blastocyst formation rate. We designed a prospective randomized study comparing two different embryo culture strategies: group and individual embryo culture. The data were obtained from 830 embryos from 103 egg donation treatments. The zygotes were randomized into two groups: individual culture (group 1) or group culture (group 2). The embryos were cultured in 35-µl drops until day 5 when they were classified morphologically. We observed a significant increase in the blastocyst formation rate and in the usable embryo rate in individual culture on day 5 compared to group culture. However, good embryo quality (A/B blastocysts), implantation, and pregnancy rates were similar regardless of the type of embryo-culture. As a conclusion, individual culture may increase blastocyst formation rate and may benefit embryo quality on day 5. Our results support previous reports suggesting that individual culture could improve embryo development.

Enhancing the Performance of Nanocrystalline SnO2 for Solar Cells through Photonic Curing Using Impedance Spectroscopy Analysis.

Wide-bandgap tin oxide (SnO2) thin-films are frequently used as an electron-transporting layers in perovskite solar cells due to their superior thermal and environmental stabilities. However, its crystallization by conventional thermal methods typically requires high temperatures and long periods of time. These post-processing conditions severely limit the choice of substrates and reduce the large-scale manufacturing capabilities. This work describes the intense-pulsed-light-induced crystallization of SnO2 thin-films using only 500 µs of exposure time. The thin-films' properties are investigated using both impedance spectroscopy and photoconductivity characteristic measurements. A Nyquist plot analysis establishes that the process parameters have a significant impact on the electronic and ionic behaviors of the SnO2 films. Most importantly, we demonstrate that light-induced crystallization yields improved topography and excellent electrical properties through enhanced charge transfer, improved interfacial morphology, and better ohmic contact compared to thermally annealed (TA) SnO2 films.

Grain Structure Engineering in Screen-Printed Silver Flake-Based Inks for High-Temperature Printed Electronics Applications.

We extensively studied serigraphic screen-printed commercial silver flake inks loaded with silicon inclusions in order to achieve pinning at the grain boundaries. Based on grain size measurements using electron backscattered diffraction (EBSD), commercial silver ink with silicon microparticle content of 5 wt.% shows significant grain growth retardation compared to pristine silver ink, which stabilizes electrical conductivity up to 700 °C via a Zener pinning mechanism. The modified silicon-loaded silver ink experiences a two-times increase in grain size when heated up to 700 °C, compared to a seven-times increase for pristine silver ink. In turn, this enables operation temperatures significantly higher than the conventional operational window of microparticle-based silver inks, which are usually limited to 400 °C. Using isothermal exposures of 10 min up to 4 h, this phenomenon is observed at temperatures ranging from 250 °C to 900 °C. The electrical conductivity stability, grain size evolution and oxide contents were studied up to 4 h. The activation energy of silver ink with silicon inclusions is 54% lower than for pristine silver ink due to the pining effect, which retards grain growth via the Zener mechanism. Most importantly, the electrical resistivity remains stable up to 700 °C, which is more than twice the operation limit for off-the-shelf screen-printable silver flake inks. Hence, we demonstrate that adding controlled amounts of silicon particles to silver inks for grain structure engineering can open new vistas of possibilities for screen-printed metallic inks.