Grounding scheme for multiple PCB's

I am working on a project called biochemistry analyzer in which there are many PCBs like Main Board, Photo detector (ADC) board, Printer PCB, LCD, Smart card board etc. In this application, power supply regulator IC's are on Main Board from which Gnd is shared between multiple PCB's through jumper.

There are various possibilities how I deal with Ground trace and plane.

Possibility 1: Complete bottom layer of Gnd plane on Main Board ( where regulator chips are located ) and through jumper taking gnd to another board and then using trace ( instead of plane)

Possibility 2: Assigning plane on All PCB's but this will be little cumbersome and I don't know whether it's good idea or not.

If there is any other option which will be best suited because this instrument is analytical analyzer where precise ADC is required and photodiode is used.

So please suggest good grounding scheme.

Wide flat braid between boards with ground planes and true differential balanced I/Os with controlled impedance will help.

This may require choosing between remote signal processing , and more shielding and isolation from noise generators and to all high impedance inputs with ferrite baluns.

Good EMI design considers the elimination of interference :fight: by isolation and attenuation of both the conducted and radiated noise and susceptibility of each interface. Isolation, orientation and both differential and common-mode noise. :fight:

Consider a laptop teardown and examine how braid and flex circuit shielding is done for each of the peripherals.