A spill-resistant container lid that gives the user the feeling that there is no lid at all. Each antenna element communicates an RF signal in a direction that corresponds with an outer face of a housing of the assembly. Monitoring, and processing means to interpret the results are comprised in an external coagulometer device. Two types of coding are utilized in order to reduce the amount of data; inter-coding, which takes into account a corresponding block in a previous picture and intra coding, which is independent from a previous picture.