DC current limiter micro-amps
Siliconix Application Note AN103 may be of interest.


  The combination of low associated operating voltage and
  high output impedance makes the FET attractive as a
  constant-current source. An adjustable-current source (Figure
  1) may be built with a FET, a variable resistor, and a
  small battery. For optimum thermal stability, the FET should
  be biased near the zero temperature coefficient point.




Figure 1. Simple FET current source.

The application note goes into considerable detail so you may find something suitable.