Table 2. Mechanical stimulus delivery methods.

	Tool or devicea	Stimulus amplitude	References
Classical or qualitative	Eyebrow hair	Variable, 20–800 µN	Sulston et al. (1975), Chalfie and Sulston (1981), Nekimken et al. (2017b)
	Wire pick	Unknown	Way and Chalfie (1989)
	Plate tap	Unknown	Rankin and Broster (1992)
Quantitative approaches	Flexible glass probe (open loop)	Force, nN - µN	O’Hagan et al. (2005)
	Stiff glass probe (open loop)	Displacement, µm	Suzuki et al. (2003)
	Microcantilever (feedback control, closed-loop)	Displacement (µm) or force (nN-µN)	Park et al. (2007), Petzold et al. (2013), Eastwood et al. (2015)
	Pneumatic, microfluidic devices	Pressure-induced displacement (µm)	Cho et al. (2017), Nekimken et al. (2017a)

^aSee also Chalfie et al. (2014).