this doesn't mean that it sounds too good to be true.
edit: fixed units - dont have easy access to micro, thanks for pointing that out.
You can spell it out, like "91 micronewtons".
You can also use exponential notation like 91e-6 N or 91x10^(-6) N.
To be fancy you can copy-and-paste unicode characters and write 91×10⁻⁶ N.
(I follow the subject by browsing news now and then at http://talk-polywell.org/ which really is about the small fusion projects. That place should have more details then at Wired.)
Use 'μ' for micro, 'm' is for milli.