Purpose: This study discusses the design, fabrication and testing of MEMS based impedance biosensors for onsite detection of three Salmonella serogroups simultaneously with high selectivity and sensitivity at low concentration within 30 minutes in poultry products.
Methods: The biosensor consists of three microfluidic channels, each includes (1) a region for concentrating and directing Salmonella cells toward the sensing microchannel using AC signal at specific frequency, (2) a region for bacteria detection based on impedance measurements. The three detection electrode surfaces were functionalized with three mixtures of premixed Salmonella antibody (type B, D and E)-cross-linker (Sulfo-LC-SPDP) solution, one for each channel and without causing any cross-contamination. The poultry samples were spiked with Salmonellatype B and introduced via the sample inlet towards the focusing region. The antigen-antibody binding results in change in impedance. The biosensor was fabricated on a glass substrate using surface micromachining technology.
Results: The biosensor demonstrates capability to selectively detect Salmonella type B with a concentration as low as 7 cell/ml, and 10 cell/ml in turkey ready-to-eat (RTE) and raw chicken samples, respectively, with detection time of 30 minutes. The other two channels that were coated with Salmonellaantibody type E and D have weak signals. The addition of focusing region has improved the signal strength by a factor ranged between 4 and 18.
Significance: Our biosensor allows poultry industry to test their products in-shift enabling them to delay the sanitation cycle e.g., from 1 day to 2 days increasing the production line’s running hours.