This paper presents the design of an extremely low-energy biosensing platform that utilizes voltage to time conversion and time-mode signal processing to sense and accommodate electrophysiological biosignals that will be later sent remotely using a simple and low power communication scheme. The electrode input is fed to a chain of monostable multivibrators used as analog-to-time converters, which create time pulses whose widths are proportional to the input signal. These pulses are transmitted to an external receiver by means of single-pulse harmonic modulation as the communication scheme, at a carrier frequency of 10 MHz. The platform is designed to be implemented in a standard 0.18μm IC process with an energy dissipation per sample per channel of 42.72 pJ, including communication, operating from a supply voltage of 0.6V with an input referred noise of 12.3 μVrms. The resulting SNR for OSR=256 is 35.19 dB, and the system’s power consumption at a sampling and communication rate of 256 Hz is 10.94 nW.