How can you improve interaction between team members?
Tell the team that you see this as a problem and ask them to solve it Moving people around and redesign the office space can improve interaction between team member and it is well documented:
Ask the team if they would like to do something recreational together and offer to organize it
Move people's workstation around in the team room to create new social possibilites
Since no one has come to you with a compliant, assume that the limited interaction works for everyone