TECHNIQUE	SCALE	ADVANTAGES	LIMITATIONS	REFERENCES
	Molecular	+ Ability to measure forces at molecular level in intact tissues	− Difficult validation process − Unable to obtain directional information − Molecular scale may not reflect cell- or tissue- scale tensions	(Conway et al., 2013; Saeger et al., 2012)
	Molecular	+ Ability to tether proteins and cells at nanometer resolution and under physiologica conditions.	− Receptor- ligand bond strengths may differ from in vivo due to complex biological interactions. − Difficult to run experiments at high velocities due to viscous drag from cantilevers.	(Puech et al., 2005)
	Molecular	+ Detection of bond rupture forces with picoNewton sensitivity. + Micron sized trapped beads allow for more	− Receptor- ligand bond strengths may differ from in vivo due to complex biological interactions. − Limited rangel of detectable forces (large forces yield non-linear force- deformation Irelationships	(Perret et al., 2004) (Bayas et al., 2006)
	Molecular- Cell	+ Isolation of single molecules + Precise control of force application.	− Receptor- ligand bond strengths may differ from in vivo due to complex biological interactions. − Requires optically homogeneous and highly purified samples. − Local heating of sample, potentially perturbing mechanics	(Litvinov et al., 2002)
	Cell	+ Ability to grasp and move cells into contact with other cells or substrate	− Requires substantial deformation of cells. − Cells removed from native environment	(Maitre et al., 2012)
	Cell	+ Obtain cell surface tensions	− Dependent on contact time between cell pairs − Cells removed from native environment	(Maitre et al., 2012) (Manning et al., 2010)
	Cell-tissue	+ Can be done in vivo + Genotype to phenotype relationship	− Not mechanically quantitative − May change cell identity over time course of experiment	(Kafer et al., 2007) (Dray et al., 2013)
	Tissue	+ Directly measure tissue relaxation after application of known loads	− Requires spherical aggregates − Risk of changing cell identities over time course of experiment	(Foty et al., 1994a)
	Tissue	+ Simple prep + Obtain whole tissue surface tension measureme nts	− Requires spherical aggregates − Risk of changing cell identities over time course of experiment	(Kalantarian et al., 2009)