an aptamer - based solid - state electrochemical biosensor for label - free detection of salmonella enterica serovars utilizing immobilized aptamers . the device is realized by forming a matrix array of parallel capacitors , thus allowing the realization of low - cost , portable , fully integrated devices . protein - aptamer binding modulates the threshold voltage of a circuit , changing the impedance of the circuit . this circuit is further characterized by an electrode coded with a p - si substrate , enhancing the affinity between the salmonella outer membrane proteins and the aptamer . an aptamer embedded detection plate is configured within a testing lid device that fits a standard , commercially available polymer specimen jar . a sample is mixed with broth for incubation and cultivation of any present salmonella bacteria to obtain acceptable concentration of the pathogen for testing . the information obtained can then be transmitted by wireless network .