Large array of GFETs for extracellular communication with neuronal cells

Graphene has already shown its high ability for biosensing. Solution-gated graphene field effect transistors, which showed very high sensitivity in electrolytes [1], have another biologically important application: recording neuronal activity. Such devices exhibit very high signal-to-noise ratio for extracellular measurements [2]. The aim of this work is to optimize and scale both fabrication procedure and measurement system. When working with biological samples, there is a need in a large number of devices. High density of the devices is also preferable. Therefore we fabricate the devices on 4’’ wafer, resulting in 50 chips, 11*11mm each. Each chip consequently embodies an array of 32 graphene FETs (see fig.1). The active area of the chip is around 2 mm2 while each GFET’s channel differs between 5 and 20 um with altered configurations. Such devices, when used with the already developed multichannel measurements system make possible simultaneous measurement and stimulation of all 32 transistors in a time-scale. This makes possible to measure not just discrete spikes, but even propagation of the action potential through the neuronal network

Intra-Genomic Ribosomal RNA Polymorphism and Morphological Variation in Elphidium macellum Suggests Inter-Specific Hybridization in Foraminifera

Elphidium macellum is a benthic foraminifer commonly found in the Patagonian fjords. To test whether its highly variable morphotypes are ecophenotypes or different genotypes, we analysed 70 sequences of the SSU rRNA gene from 25 specimens. Unexpectedly, we identified 11 distinct ribotypes, with up to 5 ribotypes co-occurring within the same specimen. The ribotypes differ by varying blocks of sequence located at the end of stem-loop motifs in the three expansion segments specific to foraminifera. These changes, distinct from typical SNPs and indels, directly affect the structure of the expansion segments. Their mosaic distribution suggests that ribotypes originated by recombination of two or more clusters of ribosomal genes. We propose that this expansion segment polymorphism (ESP) could originate from hybridization of morphologically different populations of Patagonian Elphidium. We speculate that the complex geological history of Patagonia enhanced divergence of coastal foraminiferal species and contributed to increasing genetic and morphological variation

A many-analysts approach to the relation between religiosity and well-being

The relation between religiosity and well-being is one of the most researched topics in the psychology of religion, yet the directionality and robustness of the effect remains debated. Here, we adopted a many-analysts approach to assess the robustness of this relation based on a new cross-cultural dataset (N=10,535 participants from 24 countries). We recruited 120 analysis teams to investigate (1) whether religious people self-report higher well-being, and (2) whether the relation between religiosity and self-reported well-being depends on perceived cultural norms of religion (i.e., whether it is considered normal and desirable to be religious in a given country). In a two-stage procedure, the teams first created an analysis plan and then executed their planned analysis on the data. For the first research question, all but 3 teams reported positive effect sizes with credible/confidence intervals excluding zero (median reported β=0.120). For the second research question, this was the case for 65% of the teams (median reported β=0.039). While most teams applied (multilevel) linear regression models, there was considerable variability in the choice of items used to construct the independent variables, the dependent variable, and the included covariates

A Many-analysts Approach to the Relation Between Religiosity and Well-being

The relation between religiosity and well-being is one of the most researched topics in the psychology of religion, yet the directionality and robustness of the effect remains debated. Here, we adopted a many-analysts approach to assess the robustness of this relation based on a new cross-cultural dataset (N = 10, 535 participants from 24 countries). We recruited 120 analysis teams to investigate (1) whether religious people self-report higher well-being, and (2) whether the relation between religiosity and self-reported well-being depends on perceived cultural norms of religion (i.e., whether it is considered normal and desirable to be religious in a given country). In a two-stage procedure, the teams first created an analysis plan and then executed their planned analysis on the data. For the first research question, all but 3 teams reported positive effect sizes with credible/confidence intervals excluding zero (median reported β = 0.120). For the second research question, this was the case for 65% of the teams (median reported β = 0.039). While most teams applied (multilevel) linear regression models, there was considerable variability in the choice of items used to construct the independent variables, the dependent variable, and the included covariates

Wafer-scale fabrication of graphene-based field effect transistor arrays for extracellular measurements

The work is focused on the fabrication and analysis of graphene-based, solution-gated field effect transistor arrays (GFET arrays) in a large scale. The GFETs show extremely high electrolyte-gated transconductance promising exceptional biosensing capability. Signal-to-noise ratio (SNR) of the GFETs is analysed for different graphene areas. In the future we will apply these GFETs for extracellular recordings from neuronal and cardiac cells

Wafer-scale fabrication of graphene field effect transistors for neuronal interfacing

There are plenty of invasive methods for studying a neuronal network’s activities [1]. Of course, the invasiveness of the processes makes them undesired. In recent years, there has been vast research in the field of non-invasive neuronal interfacing and extracellular neuronal recordings [2]. Different methods (passive – MEAs and active – FETs) and different materials (carbon, silicon, PEDOT:PSS) have been used for the purpose.Graphene’s excellent electrical, mechanical and biological properties make it a perfect candidate for such a role. Firstly, liquid-gated graphene field effect transistors (GFETs, see fig. 1) show very high transconductance, and therefore sensitivity [3]. Secondly, graphene is a very stable and biocompatible material (fig.2). Thirdly, flexibility and bendability of graphene make it the most promising material for future bio-implantable devices [3].Therefore we established our 4-inch wafer fabrication process based on CVD-grown graphene (fig. 3a). Each fabricated wafer results in 52 biocompatible chips (fig. 3b). Each chip comprises 32 GFETs (fig. 3c). The size of graphene active area is varied in order to study the noise of the system. Each chip is measured on a multi-channel measurement system, which allows us to measure all the GFETs simultaneously. Thus, it is possible to measure not just single action potentials of the electrogenic cells, but even propagation of the potential through the network

Planar reference electrodes on multielectrode arrays for electrochemical measurements of ionic currents

We describe the fabrication process and characterization of polymer coated multielectrode array chips featuring 64 planar Ag/AgCl electrodes for electrophysiological and electrochemical measurements of ionic currents. The multielectrode chip consists of platinum feedlines and microelectrodes fabricated on an oxidized silicon substrate. The feed lines are passivated with a polyimide layer. Silver is deposited electrochemically on the platinum electrodes and chlorinated afterwards resulting in stable micro Ag/AgCl reference electrodes that are recessed within picoliter cavities. We envisage the chip as a platform for high-throughput investigation of lipid bilayers