Evaluating Performance of Polymeric Biosensor by a Single Multichannel Micro Electrode Array in a Portable Monitoring System for Preventing Drug Resistance Epilepsy Defects

Introduction: There are several proven methods to investigating neural activities of electro genic cells in different points of human’s body. Within these methods, performing electronic tools such as biosensors for monitoring different signals of brain, heart and other pulses such as breath simultaneously during daily routines in different balance of cautions can improve the choice of treatment progress in some neuro disorders such as drug resistance epilepsy. Therefore, in this research attach to technical science of production a polymeric biosensor with a multichannel micro electrode array (MEA) with capability of touch the brain signals on scale, it was attempt to make a portable monitoring system to record and investigating signals by navigating them into a smart cellphone. Through this method by detecting critical signals on threshold of seizures in aura state can prevent most defects even SUDEP with release an alert on cellphone rather start recording the seizure activities through interictal spikes to post investigations. However, localizing electrode on the specific point close to seizure prediction horizon (SPH) with no need to electrolyte gel can obtain a non-invasive method with suitable accuracy to touch and scanning brain signals on scale. Modelling and methods: The set-up which contains a 64-channel MEA with capability of infrastructural electromagnetic waves amplification and an interface circuit with four main parts i.e. Power supply, Opamp, (HPF/LPF) Filters and Voltage convertor for external wave amplification and noise cancelation are used to convert brain signals to a single analysable signal for processing unit within cellphone. Wave navigation was followed by 3.5(mm) stereo jack that more than two signals further main brain signal can navigated with this as mentioned earlier. The accuracy of MEA can be improved by thin layering a biocompatible conductive polymer such as PEDOT: PSS on a flexible substrate to increase touch surface area of electrode with skin. Now, after calculating a parameter known as signal to noise ratio (SNR) with detection probability of signal and noise (Pi): (Eq.1) if SNR~N, then according to wave law: → (Eq.2) Therefore, by defining distinct value for landa as λn,crit then seizure possibility index (SPI) to release a command by processor after detecting this critical point by signal analysis is: (Eq.3) Results and discussion: Brain activity with 10-20 (mV) amplitude by 100 (μV) oscillating and frequency bellow 30 (Hz) can be sensed by conventional electrodes and electrolyte gel beneath the contact surface, but this amplitude could increase up to 1 (V) with dry MEA with own of symmetric shape of electrode. On the other hand, using an Opamp this value can be increased more by signal amplification between each channel with other ones. whereas the mentioned MEA has 4 main sites with 16 channels in each site, after oscillography and detecting the reference channel, output signal of each site should be amplified with each other too that results showed that wave amplification between two cross sites was better than two adjacent sites. However, by eliminating artifacts and strong signals after weak signals respectively by HPF and LPF can attach a suitable signal that using mathematic methods such as FFT algorithm can detect seizure critical peaks on it even on amplitude vs. time area in 3D mode. Figure1. (a) the final set up; (b) the electrode localization; (c) The signal in two and three dimensional modes; (d) Electrode structure with four main 16-channel sites. Fig2. Comparison of efficiency and accuracy coefficients, for MEA, amplified signal between cross-sites, and conventional electrodes whether before and after noise cancelation. Conclusion: Though, comparing the efficiency of MEA with conventional wet electrodes showed perfect value for MEA, but accuracy vice versa. Nevertheless, close accuracy whether after and before noise cancellation during repeated experiments showed good performance of this biosensor for brain signals scanning.