A novel planar interdigital sensor based sensing system has been developed for detection of dangerous marine biotoxins in seafood. Our main objective is to sense the presence of dangerous contaminated acid in mussels and other seafoods. Initial studies were conducted with three peptide derivatives namely Sarcosine, Proline and Hydroxylproline. These three chemicals are structurally closely related to our target molecule. The proline molecule is arguably the most important amino acid in peptide conformation, contains the basic structural similarity to the domoic acid. Three novel interdigital sensors have been designed and fabricated. All sensors have the same effective area but having different sensor configurations. The initial results show that sensors respond very well to the chemicals and it is possible to discriminate the different chemicals from the output of the sensor. The sensors were also being tested with three seafood products. Results from the analysis have shown that sensor with configuration #1 (Sensor-1) has better sensitivity compared to other sensors. Sensor-1 was chosen for experiment using proline and mussels. The changes in sensor sensitivity were analysed with mussels before and after adding the proline. The presence of proline on the mussel surface and also injected proline to the mussels was very clearly detected by the sensor. Further experiment was conducted with small amount of domoic acid (0.5 μg to 5.0 μg) injected to a mussel and it was found that Sensor-1 was able to detect small amount of domoic acid (1.0 μg) injected into the mussel sample. The result shows that Sensor-1 was able to detect approximately 12.6 μg/g of domoic acid in mussel meat. Three threshold levels of particular sample thickness have been established for detection of domoic acid. The first prototype of a low cost sensing system known as SIT (Seafood Inspection Tool) has been developed. The outcomes from the experiments provide chances of opportunity for further research in developing a low cost miniature type of sensors for reliable sensing system for commercial use.