"node" which can hold different values to be read by a sensor?
The first thing that comes into my mind with what you have said is RFID. Your "nodes" would be passive tags which get powered up when the reader gets close (thanks to wireless power transmition). Then your node answers to the reader sending an ID.

You say your "nodes" are electrically passive, but want them to be able to transmit complex and programmable information. So another option would be using small button-baterry powered microcontrollers which could last several years on a single battery charge. You could even take it a step further and use one of the many sorts of energy harvesting technologies to remove the battery all together.

Could you please elaborate your requieremnts? We will try to provide you with the best answer once we know your specific requirements :)



EDIT 02-10-2016

Let me see if I got it right ;)


  You have an array of "smart" sensors, each of which is consist of the
  actual sensor and some smart electronics that can be programmed to
  inform about the sensor output and of its unique ID (and maybe other
  variable/programable data). 
  
  These sensors are laid out in front of the user, which accesses them
  with a reader. In case of RFID it could be the actual RFID reader, but
  becaouse they are so close together and you want to avoid
  interferences, you prefer a conductive stick.
  
  When the user touches one of the sensors with the stick, you want the
  sensor to send it's data through that stick to an end device. This
  end-device could be your smartphone, and the stick is connected to it
  through the USB port.


Some more daditional info would help me a lot here to decide which approach to take. But if a client of mine really wanted such a setup I would encourage him to reconsider.

If you want to send data over a conductive stick, this data has to be sent preferably using a single wire serial port, like RS-232 (UART). 

Which is actually possible. Once you make electrical contact, you can receive data. Nevertheless, small bounces (while making contact) would make this circuit unreliable.

I would do something different, with a similar end result:


  Have all smart-sensors carry a small button on top. Then interconnect
  them using an appropriate communications bus, like I²C in multi-master
  mode. Finally, ad to your multi-node system a node with Bluetooth
  which connects to your smart-phone.
  
  Once a smart-sensor detects you have pressed its button, its sends to
  the Bluetooth node all information you want, which you can then
  receive on your smart-phone.


I hope you find this useful, but your question is really complicated and I would need more details. For example, why don't you upload a simple pseudo-schematic of what your want, or a small flow diagram :)

Good luck!