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project:brain_hacking:tdcs [2013/03/12 11:15]
ata
project:brain_hacking:tdcs [2013/04/29 22:05] (current)
ata F3 locator (program)
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 **Ramping capacitor - possible problem ** **Ramping capacitor - possible problem **
-  *Yesterday i was bulding some tDCS with LM334 and try for first time use ramping capacitor. When i test device with load (5KOhms) all was ok ramping when i turn device on and ramping down when of. But when i change load (5kOhms potentiometer) during stimulation (testing) it create current peak up to 5 mA. I test it with few different capacitor and behavior is alwayes ​the same (only diffrent value of peak nad the time to return to normal ). Device without capacitor work witkout poroblem. In resuls ​of this i use instead of capacitor serail load (bid linear potentiometr 100kOhms ) allows me to do manual ramping (0,07mA to setup current).+  *Yesterday i was bulding some tDCS with LM334 and try for first time use ramping capacitor. When i test device with load (5KOhms) all was ok ramping when i turn device on and ramping down when off. But when i change load (5kOhms potentiometer) during stimulation (testing) it create current peak up to 5 mA. I test it with few different capacitor and behavior is allwayes ​the same (only diffrent value of peak nad the time to return to normal ). Device without capacitor work witkout poroblem. In result ​of this i use instead of capacitor serail load ( linear potentiometr 100kOhms ) allows me to do manual ramping (0,07mA to setup current).
  
 My question is can anybody test this capacitor problem maybe i do semething wrong , bad multimetter etc.. . If is this problem real is very bad idea use capacitor for ramping in use the resistance change is not to quick but stil can cause pretty high current peaks. My question is can anybody test this capacitor problem maybe i do semething wrong , bad multimetter etc.. . If is this problem real is very bad idea use capacitor for ramping in use the resistance change is not to quick but stil can cause pretty high current peaks.
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 NOT TESTED only ideas :  NOT TESTED only ideas : 
   * Polyimid resistive foil (50um , 100 Ohm/cm2 ) http://​www.gme.cz/​vodive-pryze/​polyimidova-odporova-folie-26x20cm-100ohm-p661-130/​   * Polyimid resistive foil (50um , 100 Ohm/cm2 ) http://​www.gme.cz/​vodive-pryze/​polyimidova-odporova-folie-26x20cm-100ohm-p661-130/​
-  * Carbon/grafite ​electrode for HD-tdcs , cleaned carbon ​electrode ​form old battery ​(Ohm/cm2 ? , stabilty ​?, clean enought ​? )  + 
 +---- 
 +7.4 2013 
 + 
 + 
 +Prof. Marom Bikson “Using Computational Models in tDCS Dose” 
 +http://​www.diytdcs.com/​2013/​04/​prof-marom-bikson-using-computational-models-in-tdcs-dose/​ 
 +  * about problems with extracephalic electrodes  
 +  * HD-tDCS electrodes - not use saline soaked sponge -) risk of burn  
 +    *i plan test skin tolerability and sensation limits for sponge based HD-tDCS electrodes ​  
 +  * direction of current (in , out , tangental , radial) 
 +  * Comparing cortical plasticity induced by conventional and high-definition 4x1 ring tDCS 
 +    *time course difference , longer effect 
 +  *focality of HD-tDCS 
 +  *Inter-subject variation in susceptibility >2x in TES 
 +  *Dose normalization:​ Determine role of individual variation and predict requisite adjustments in subject 
 +specific dose. 
 + 
 + 
 + 
 +Comparing cortical plasticity induced by conventional and high- 
 +definition 4x1 ring tDCS: a neurophysiological study  
 +Brain Stimulation 2012  
 +Kuo HI, Datta M, Bikson M, Minhas P, Paulus W, Kuo MF, Nitsche MA  
 + 
 +---- 
 +8.4 
 +Test of HD-tDCS electrodes  
 + 
 +   * problem with contact to polyimide foil  
 +   * current desity with no pain/tingeling  
 +    *270 uA/​cm2 ​ for saline soaked sponge  
 +    *320 uA/​cm2 ​ for TEN20 EEG gel  
 +    *(3,14cm2 electrodes on skin , cleaned by alcohol pad and abrasion by nuprep )  
 +   * voltage problem after skin preparation 8,3 V at 1mA (9V power suply ) to close to the device limit  
 +    --------) rebuild device to 18V version  
 + 
 +---- 
 + 
 +9.4 
 +  *rebuild to 18V version  
 +  *too strong abrasion by nuprep -) increased pain in stimulation (damaged skin by abarasion) 
 +  * current desity test up to 620uA/cm2 
 +    * its posible stimulate with 620uA/cm2 without any fealing but result are not stable and is needed electrode improvements  
 +    * better result for EEG gel than for saline soaked sponge  
 +    * saline soaked sponge : not even saline distribution ? , to dry ? ---) more tests  
 + 
 +to do: 
 +    *rebuild electrodes from 3,14cm2 to 4 cm2 ( to reduce current density , new info : soterix use 4cm2 ,easier counting of current density )   
 +    *lower height of elastic ring around electrode for EEG gel electrodes ( too much consumption of EEG gel )  
 +    *sponge electrodes : Filling tube for guaranteed the same moisture for whole stimulation 
 +      *sringe  
 +      *gravity autofilling (3cm filling tube) 
 +       *head movement caused spillage ? , end of the tube ?  
 +      *improve elastic ring (reduce spillage of saline) ​    
 +    * electrode cap for M1/SO 35cm2  
 +      *fixation to holder 
 +      *faster shape adjusting  
 +    * electrode ​cap for 4X1 M1 HD-tDCS   
 +      *EEG gel electrodes adhesion : usage witout cap ? 
 +    * EEG electrode cap for 4X1 M1 HD-tDCS  
 +      *hair problem in EEG cap --) find something to move away hair 
 +      *holder allows one by one electrodes adding (easier to move away hair than in version where all electrodes fimly fixed to 4x1 holder) 
 +    * TESTS painless/​sesationless current desities for all types of electrodes , alcohol Y/N ,abrasion Y/N , alcohol + abrasion  
 +      * arm or leg , forehead, hair area    
 + 
 +    *few interesting designs of caps 
 + ​{{http://​biomedicaloptics.spiedigitallibrary.org/​data/​Journals/​BIOMEDO/​926250/​JBO_18_2_027005_f001.png}} 
 + 
 +[[http://​biomedicaloptics.spiedigitallibrary.org/​article.aspx?​articleid=1567852]] 
 +  
 +{{ http://​www.wired.com/​images_blogs/​gadgetlab/​2011/​03/​3-22-11-mynd-eeg-headset.jpg }} 
 + 
 +{{http://​gearmedia.ign.com/​gear/​image/​article/​772/​772295/​gdc-2007-emotiv-systems-unveils-shocking-neural-interface-device-20070312035005901-000.jpg}} 
 + 
 +   * dry electrodes 
 +     * HD tdcs dry electrodes are crazy idea but worth some tests like current desity without iritation and hi-frequenci pulsed TDCS (4khz) 
 +       ​*comercial EEG dry electrodes  
 +{{http://​www.gtec.at/​var/​plain_site/​storage/​images/​media/​images/​products/​g.sahara/​gsaharalongpin/​26508-1-eng-GB/​gSAHARAlongpin.jpg}} 
 + 
 +{{http://​beweb.ucsd.edu/​courses/​senior-design/​projects/​2010/​project_17/​electrode.jpg}} 
 + 
 + 
 +------- 
 +11.4 
 +  
 +    *<​del>​rebuild electrodes from 3,14cm2 to 4 cm2 ( to reduce current density , new info : soterix use 4cm2 ,easier counting of current density ) </​del>​ **rebuild to 4,9cm2** 
 +     
 +    *<​del>​lower height of elastic ring around ​electrode ​for EEG gel electrodes ​too much consumption of EEG gel )</del> **OK (ring from tape)**  
 +    *<​del>​sponge electrodes : Filling tube for guaranteed the same moisture for whole stimulation</​del>​ **OK** 
 +           ​*<​del>​sringe</​del>​  
 +           ​*<​del>​gravity autofilling (3cm filling tube)</​del>​ **Change of design** 
 +           ​*<​del>​head movement caused spillage ​? , end of the tube ?</​del>​ **OK (capilar effect)** 
 +           ​*<​del>​improve elastic ring (reduce spillage of saline)</​del>​ **OK** ​    
 +    *<​del>​electrode cap for M1/SO 35cm2</​del>​ **OK** 
 +    *<​del>​fixation to holder</​del>​ **OK** 
 +    *<​del>​faster shape adjusting</​del>​ **OK**  
 +    
 +    <​del>​*electrode cap for 4X1 M1 HD-tDCS </​del>​  
 +    *<​del>​EEG gel electrodes adhesion : usage witout cap ?</​del>​ **OK** 
 +      *holder allows one by one electrodes adding (easier to move away hair than in version where all electrodes fimly fixed to 4x1 holder) 
 +    *<​del>​EEG electrode cap for 4X1 M1 HD-tDCS hair problem in EEG cap --) find something to move away hair</​del>​ **Hole in cap is too small to put in electrode from top** 
 +    * TESTS painless/​sesationless current desities for all types of electrodes , alcohol Y/N ,abrasion Y/N , alcohol + abrasion  
 +      * arm or leg , forehead, hair area    
 + 
 +**TO DO** 
 +    *elstic rings 
 +    <​del>​*filling tube 
 +    *elctrode holder 
 +    *HD-TDCS cap</​del>​ 
 +    *TESTS 
 + 
 +----------------- 
 + 
 +29.4 
 +**Usefull tool for locating DLPFC**  
 + 
 +An efficient and accurate new method for locating the F3 position for prefrontal TMS applications 
 + 
 +http://​www.ncbi.nlm.nih.gov/​pmc/​articles/​PMC2882797/​ 
 + 
 +http://​clinicalresearcher.org/​F3/​ 
  
 **My Email** **My Email**
 ORLIN1@seznam.cz ​ ORLIN1@seznam.cz ​
 
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