When a bundle with a drag coefficient of 200 nN · sec · m⁻¹ (Howard and Hudspeth, 1988) produced a 25 nm, triangle-wave twitch 5 msec in total duration (Fig. 12A), the energy dissipated against viscous drag was ~100 zJ (a zeptojoule is 10⁻²¹ J).
Source: wiktionary
The associated work is
W = 38.5 nm² × (10⁻⁹m/nm)² 35 pN/μm
(10⁻¹² N/pN) (μm/10⁻⁶ m) = 1.35 × 10⁻²¹ J
or about one zeptojoule.
Source: wiktionary
However, with zeptojoule scale switching energies and novel functionality, the BiSFET could add a substantial amount of road!
Source: wiktionary