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ADUCM350 Recommended for New Designs
The ADuCM350 is a configurable Impedance Converter and Potentiostat with current and voltage measurement capability for both Electrochemical sensors and...
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ADUCM350 on Analog.com

AD8226 Production
The AD8226 is a low cost, wide supply range instrumentation amplifier that requires only one external resistor to set any gain between 1 and 1000. The...
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AD8226 on Analog.com

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Using electrodes with ADuCM350 4 Wire BioZ board

		
	
				

			

									
					    Majo
					
							

            
            			
				
									
											
			
			
				
			
			
			    	
			                    
                
				                on May 2, 2016 
				
			
			
		

		
		                     
				
        		

		    
		    		    
		    			

			    
Hi Eoghan, 

 
I would like to ask you for advice.

 
I do not know if I am doing again something wrong. 

 
Today I wanted to try measure with 4 electrodes system. 

 
I found on the analog device site (4Wire-Isolated-Bioimpedance ADuCM350 Connections To Sensor), that when I want to measure with 4 electrodes I have to remove all links besides (LK7 - LK10) and all R_access resistors. So, I did this. I put the wires on that places and I connected the AD8226 as is pictured in pdf (http://www.analog.com/media/en/technical-documentation/application-notes/AN-1302.pdf - page 14 to 15). 

 
The measured output is different that I expected. When I increase the frequency the impedance is increasing. And I also tried to measure the output from AFE8 with oscilloscope and I am not able to measure anything. Maybe the measured impedance is therefore wrong because there is no output or lots of noise. 

 
Thanks in advance

 
Best regards

 
Marian

			

			
									
		                             
                        

    

                                            
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    •  Analog Employees  
    
            
						
                            
            
            				
            
                on May 3, 2016 3:14 AM
            
            
						
			            		
    
		
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    Hi Marian,
    
 
    What frequency did you use for this measurement? Did you change any other parameters?
    
 
    Measuring the AFE output using a standard oscilloscope probe will lead to errors in the measurement. The additional load of the scope probe will affect the measurement. If you want to measure the AFE response, you should measure outside the loop (e.g. the TIA output, TIA_O) or use active scope probes (a force-sense measurement).
    
 
    Rgds,
    
 
    Eoghan.
    
			
    

		
			
	      

		
		
	
    
	
    
		
    
			
		
    
	
    
	
    
		
						
						
				
						
				
				
		
		
    
			
		
    
	
    

    

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    •  Analog Employees  
    
            
						
                            
            
            				
            
                on May 3, 2016 3:14 AM
            
            
						
			            		
    
		
										0
					
	
    

		
		
    
		
    
                                
                                                            
    
					
    Hi Marian,
    
 
    What frequency did you use for this measurement? Did you change any other parameters?
    
 
    Measuring the AFE output using a standard oscilloscope probe will lead to errors in the measurement. The additional load of the scope probe will affect the measurement. If you want to measure the AFE response, you should measure outside the loop (e.g. the TIA output, TIA_O) or use active scope probes (a force-sense measurement).
    
 
    Rgds,
    
 
    Eoghan.
    
			
    

		
			
	      

		
		
	
    
	
    
		
    
			
		
    
	
    
	
    
		
						
						
				
						
				
				
		
		
    
			
		
    
	
    

    

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