Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userAll-carbon multi-electrode array for real-time in vitro measurements of oxidizable neurotransmitters
183
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
We report on the ion beam fabrication of all-carbon multi electrode arrays (MEAs) based on 16 graphitic micro-channels embedded in single-crystal diamond (SCD) substrates. The fabricated SCD-MEAs are systematically employed for the in vitro simultaneous amperometric detection of the secretory activity from populations of chromaffin cells, demonstrating a new sensing approach with respect to standard techniques. The biochemical stability and biocompatibility of the SCD-based device combined with the parallel recording of multi-electrodes array allow: i) a significant time saving in data collection during drug screening and/or pharmacological tests over a large number of cells, ii) the possibility of comparing altered cell functionality among cell populations, and iii) the repeatition of acquisition runs over many cycles with a fully non-toxic and chemically robust bio-sensitive substrate.
rate research
Read More
Cell-based biosensors constitute a fundamental tool in biotechnology, and their relevance has greatly increased in recent years as a result of a surging demand for reduced animal testing and for high-throughput and cost-effective in vitro screening platforms dedicated to environmental and biomedical diagnostics, drug development and toxicology. In this context, electrochemical/electronic cell-based biosensors represent a promising class of devices that enable long-term and real-time monitoring of cell physiology in a non-invasive and label-free fashion, with a remarkable potential for process automation and parallelization. Common limitations of this class of devices at large include the need for substrate surface modification strategies to ensure cell adhesion and immobilization, limited compatibility with complementary optical cell-probing techniques, and need for frequency-dependent measurements, which rely on elaborated equivalent electrical circuit models for data analysis and interpretation. We hereby demonstrate the monitoring of cell adhesion and detachment through the time-dependent variations in the quasi-static characteristic current curves of a highly stable electrolyte-gated transistor, based on an optically transparent network of printable polymer-wrapped semiconducting carbon-nanotubes.
Single photon avalanche diode (SPAD) arrays have proven themselves as serious candidates for time of flight positron emission tomography (PET). Discrete readout schemes mitigate the low-noise requirements of analog schemes and offer very fine control over threshold levels and timing pickup strategies. A high optical fill factor is paramount to timing performance in such detectors, and consequently space is limited for closely integrated electronics. Nonetheless, a production, daily used PET scanner must minimize bandwidth usage, data volume, data analysis time and power consumption and therefore requires a real-time readout and data processing architecture as close to the detector as possible. We propose a fully digital, embedded real-time readout architecture for SPAD-based detector. The readout circuit is located directly under the SPAD array instead of within or beside it to remove the fill factor versus circuit capabilities tradeoff. The overall real-time engine reduces transmitted data by a factor of 8 in standard operational mode. Combined with small local memory buffers, this significantly reduces overall acquisition dead time. A prototype device featuring individual readout for 6 scintillator channels was fabricated. Timing readout is provided by a first photon discriminator and a 31 ps time to digital discriminator, while energy reading and event packaging is done using standard logic in real-time. The dedicated serial output line supports a sustained rate of 170k counts per second (CPS) in waveform mode, while the standard operational mode supports 2.2 MCPS.
The detection of quantal exocytic events from neurons and neuroendocrine cells is a challenging task in neuroscience. One of the most promising platforms for the development of a new generation of biosensors is diamond, due to its biocompatibility, transparency and chemical inertness. Moreover, the electrical properties of diamond can be turned from a perfect insulator into a conductive material (resistivity Ohm cm) by exploiting the metastable nature of this allotropic form of carbon. A 16 channels MEA (Multi Electrode Array) suitable for cell culture growing has been fabricated by means of ion implantation. A focused 1.2 MeV He+ beam was scanned on a IIa single-crystal diamond sample (4.5x4.5x0.5 mm3) to cause highly damaged sub-superficial structures that were defined with micrometric spatial resolution. After implantation, the sample was annealed. This process provides the conversion of the sub-superficial highly damaged regions to a graphitic phase embedded in a highly insulating diamond matrix. Thanks to a three-dimensional masking technique, the endpoints of the sub-superficial channels emerge in contact with the sample surface, therefore being available as sensing electrodes. Cyclic voltammetry and amperometry measurements of solutions with increasing concentrations of adrenaline were performed to characterize the biosensor sensitivity. The reported results demonstrate that this new type of biosensor is suitable for in vitro detection of catecholamine release.
A microstructured graphitic 4x4 multielectrode array was embedded in a single crystal diamond substrate (4x4 {uG-SCD MEA) for real-time monitoring of exocytotic events from cultured chromaffin cells and adrenal slices. The current approach relies on the development of a parallel ion beam lithographic technique, which assures the time effective fabrication of extended arrays with reproducible electrode dimensions. The reported device is suitable for performing amperometric and voltammetric recordings with high sensitivity and temporal resolution, by simultaneously acquiring data from 16 rectangularly shaped microelectrodes (20x3.5 um^2) separated by 200 um gaps. Taking advantage of the array geometry we addressed the following specific issues: i) detect both the spontaneous and KCl-evoked secretion simultaneously from several chromaffin cells directly cultured on the device surface, ii) resolve the waveform of different subsets of exocytotic events, iii) monitoring quantal secretory events from thin slices of the adrenal gland. The frequency of spontaneous release was low (0.12 Hz and 0.3 Hz respectively for adrenal slices and cultured cells) and increased up to 0.9 Hz after stimulation with 30 mM KCl in cultured cells. The spike amplitude as well as rise and decay time were comparable with those measured by carbon fiber microelectrodes and allowed to identify three different subsets of secretory events associated to full fusion events, kiss and-run and kiss-and-stay exocytosis, confirming that the device has adequate sensitivity and time resolution for real-time recordings. The device offers the significant advantage of shortening the time to collect data by allowing simultaneous recordings from cell populations either in primary cell cultures or in intact tissues.
Active ring laser gyroscopes (RLG) operating on the principle of the optical Sagnac effect are preferred instruments for a range of applications, such as inertial guidance systems, seismology, and geodesy, that require both high bias stability and high angular velocity resolutions. Operating at such accuracy levels demands special precautions like dithering or multi-mode operation to eliminate frequency lock-in or similar effects introduced due to synchronisation of counter-propagating channels. Recently proposed bidirectional ultrafast fibre lasers can circumvent the limitations of continuous wave RLGs. However, their performance is limited due to the nature of the highly-averaged interrogation of the Sagnac effect. In general, the performance of current optical gyroscopes relies on the available measurement methods used for extracting the signal. Here, by changing the paradigm of traditional measurement and applying spatio-temporal intensity processing, we demonstrate that the bidirectional ultrafast laser can be transformed to an ultrafast gyroscope with acquisition rates of the order of the laser repetition rate, making them at least two orders of magnitude faster than commercially deploy
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
