I am a research scientist working in a university in bioinformatics in the US. To be honest, I am promoting my website, because I do believe it is super useful to you in PhD applications.
The site is called ProfessorNet, and it is designed to provide insights into professors' research fields, department structure, collaboration network and descipline trends over years. It uses public OpenAlex publication records and updates regularly.
Let's say you are in the process of hunting for labs of your interests, for example, neurobiology, you can go to the "Search Popular" page to search that. You will see a list of ranked department with that field/topic. The first one is from John Hopkins University, generally the number one in medicine in the US. Click on it and you will see the research structure of the department, including professor groups, fields, topics, each professor's publication and collaboration. This is much easier and presentable than the department directory. There is also a ranking of top professors, connections and groups. You can further search which professors are excellent in the fields you are interested and see their works.
Furthermore, you might want to choose a research field that is promising in the near future, you can check which topics are rising recently in departments. The trend mode is your friend. It will analyze the dynamics of research fields and professors' adjustment to reflect the trend of decipline. You might want to choose a rising field/subfiled rather than a falling one.
Here is an example of Biostatistics in Harvard. It analyzes the past 12 years (divided into 4 periods) in professors' research dedication and publications. Apparently, the subfield artificial intelligence has risen from 1% in 2015 to 10% this year. That trend is still moving forward today, hah? If you are interested in this department, you might want to choose this topic because it is valued by the department. Right, remember to check the trend mode results.
https://professornet.pikably.com/trend/harvard-university/department-of-biostatistics/2015-2026/3
That's my sharing of today. If you have any question or suggestion, please feel free to talk to me. I appreciate it.