The Marine Benthic Algae Diversity of Gabon: Case of the Rocky Foreshore of Cap Estérias

This study has allowed to classify the marine macroalgae from the intertidal zone on the Atlantic side of Cap Estérias (Gabon). This area has a rich biodiversity but very few studies in the knowledge of benthic macroalgae have been done. The first study on the knowledge of the algae of the Gabonese coast was made in February 1974 by John and Lawson. This article has been revised to transcribe books and our study would aim to update the existing collection. The algae census is spread over a year from August 2020 to August 2021 and is the first detailed study carried out over a year, with regard to this part of the Gabonese coast. This study has allowed to know the specific diversity, to determine the structure of the flora and its spread out over time. The results show a significant algal diversity of thirty five (35) identified species. Three classes of macroalgae were determined and the percentage of species in the class (%EC): Floridaophyceae at 50% EC, Phaeophyceae at 30% EC and Ulvophyceae at 20% EC. The red algae are the most common in the area with sixteen (16) species determined against twelve (12) species of brown algae and seven (7) species of green algae. The Phaeophyceae class presents the Dictyotaceae family which is the most diverse with 7 species found. Some species seen appear in the collection of John et al., but others are new species encountered in Gabon such as Caulerpa sertularioides, Bryopsis plumosa (two Ulvophytes), Padina arborescens which is a Pheophyte and Galaxaura filamentosa, Digenea simplex,Hildenbrandia rubra, Asparagopsis armata and Caulacanthus ustulatus which are Rhodophytes. Some species are permanently present, they are found in all seasons but with significant abundance from July to September.

Highly conformable chip-in-foil implants for neural applications

Demands for neural interfaces around functionality,high spatial resolution,and longevity have recently increased.These requirements can be met with sophisticated silicon-based integrated circuits.Embedding miniaturized dice in flexible polymer substrates significantly improves their adaptation to the mechanical environment in the body,thus improving the systems’structural biocompatibility and ability to cover larger areas of the brain.This work addresses the main challenges in developing a hybrid chip-in-foil neural implant.Assessments considered(1)the mechanical compliance to the recipient tissue that allows a long-term application and(2)the suitable design that allows the implant’s scaling and modular adaptation of chip arrangement.Finite element model studies were performed to identify design rules regarding die geometry,interconnect routing,and positions for contact pads on dice.Providing edge fillets in the die base shape proved an effective measure to improve die-substrate integrity and increase the area available for contact pads.Furthermore,routing of interconnects in the immediate vicinity of die corners should be avoided,as the substrate in these areas is prone to mechanical stress concentration.Contact pads on dice should be placed with a clearance from the die rim to avoid delamination when the implant conforms to a curvilinear body.A microfabrication process was developed to transfer,align,and electrically interconnect multiple dice into conformable polyimide-based substrates.The process enabled arbitrary die shape and size over independent target positions on the conformable substrate based on the die position on the fabrication wafer.

Bringing sensation to prosthetic hands-chronic assessment of implanted thin-film electrodes in humans

Direct stimulation of peripheral nerves with implantable electrodes successfully provided sensory feedback to amputees while using hand prostheses.Longevity of the electrodes is key to success,which we have improved for the polyimide-based transverse intrafascicular multichannel electrode(TIME).The TIMEs were implanted in the median and ulnar nerves of three trans-radial amputees for up to six months.We present a comprehensive assessment of the electrical properties of the thin-film metallization as well as material status post explantationem.The TIMEs stayed within the electrochemical safe limits while enabling consistent and precise amplitude modulation.This lead to a reliable performance in terms of eliciting sensation.No signs of corrosion or morphological change to the thin-film metallization of the probes was observed by means of electrochemical and optical analysis.The presented longevity demonstrates that thin-film electrodes are applicable in permanent implant systems.

A flexible protruding microelectrode array for neural interfacing in bioelectronic medicine

Recording neural signals from delicate autonomic nerves is a challenging task that requires the development of a lowinvasive neural interface with highly selective,micrometer-sized electrodes.This paper reports on the development of a three-dimensional(3D)protruding thin-film microelectrode array(MEA),which is intended to be used for recording low-amplitude neural signals from pelvic nervous structures by penetrating the nerves transversely to reduce the distance to the axons.Cylindrical gold pillars(O 20 or 50μm,~60μm height)were fabricated on a micromachined polyimide substrate in an electroplating process.Their sidewalls were insulated with parylene C,and their tips were optionally modified by wet etching and/or the application of a titanium nitride(TiN)coating.The microelectrodes modified by these combined techniques exhibited low impedances(~7 kΩ at 1 kHz for ∅ 50μm microelectrode with the exposed surface area of~5000μm^(2))and low intrinsic noise levels.Their functionalities were evaluated in an ex vivo pilot study with mouse retinae,in which spontaneous neuronal spikes were recorded with amplitudes of up to 66μV.This novel process strategy for fabricating flexible,3D neural interfaces with low-impedance microelectrodes has the potential to selectively record neural signals from not only delicate structures such as retinal cells but also autonomic nerves with improved signal quality to study neural circuits and develop stimulation strategies in bioelectronic medicine,e.g.,for the control of vital digestive functions.