Making a electrical signal detector (Inputs from multiple source)
I'd use an analog multiplexer in combination with a 2D matrix. An example:


Matrix of 64 sensors in an 8*8 configuration
An eight-channel analog multiplexer with three-bit address input, each input channel connected to a row of the matrix
A means of applying a voltage to each column in turn (for example, an 8-bit shift register and some transistors)
A microcontroller with built-in ADC


Connect output pins of the uC to the address pins of the multiplexer and the input, shift, reset pins of the shift register.
Connect an ADC analog input pin of the uC to the multiplexer's output
Scan the matrix by shifting columns using the shift register and reading all eight sensors on that column using the multiplexer.



Note that this assumes the variable output of each sensor is a voltage. If linearity isn't required (or you're OK with software compensation), you can build a simple voltage divider with each sensor to achieve this.