We have in the figure as a monostable a proximity switch where our body capacitance (estimated at 200 pF) can be used to pass a signal that can trigger the 4013 integrated circuit. The 4001 (or 4011) is switched on as an inverter and It is used as a trigger to provide a 60 Hz rectangular signal to the 4013. The rectangular signal comes from the noise of the power grid picked up by our body and transferred to the sensor as we approach it. A sensitivity control for this circuit can be designed by placing a potentiometer connected to the sensor as a voltage divider. The 44 M ohm resistor can be obtained by connecting two 22 M ohm resistors in series or four 10 M ohm resistors.
