Provided is a data communication method and apparatus based on a sequential response protocol that is applicable to a multiple user multiple input and multiple output system. On a substrate of a liquid-crystal device, a sampling circuit for sampling an image signal, and a data line driving circuit for supplying a sampling control signal simultaneously to each group of sampling switches connected to plural adjacent data lines are provided. The apparatus further includes an active electrode and a return electrode, wherein the return electrode comprises the shaft in combination with the introducer needle. An integrator responsive to the digital comparator produces an input signal to the ADC, which generates a corresponding digital output sample.