Fig. 5. SAR values in the low frequency range of aqueous suspension of (a) ε-Fe₂O₃ polymer coated NPs and (b) γ-Fe₂O₃ polymer coated NPs in as a function of health parameter Hf. SAR values in the high frequency range of aqueous suspensions of (c) ε-Fe₂O₃ polymer coated NPs and (d) γ-Fe₂O₃ polymer coated NPs. In the insets, details of the SAR in the health safety range of Hf. Shaded areas mark the health safety region in (a–d).