Modular photoinduced electron transfer (PET) sensors bearing two phenylboronic acid groups, one or two fluorophores: pyrene(a), phenanthrene(b), anthracene(c), 1-naphthalene(d), 2-naphthalene(e) and alkylene linkers, from trimethylene(3) to octamethylene(8), have been evaluated. Systems with a single pyrene fluorophore 3 4a, 3 5a and 3 6a bind the strongest with D-glucose (3 6a also binds well with D-melibiose). Whilst 3 7a and 3 8a bind the strongest with D-galactose. Changing the fluorophore, also, influences the binding, 3 6a, 3 6b and 3 6c are D-glucose selective, whilst 3 6d and 3 6e are D-galactose selective. Systems with two fluorophores 3 6a-a and 3 6a-b show an overall decrease in binding efficiency. Energy transfer in 3 6a-b results in enhanced sensitivity and selectivity towards D-glucose.