The dual-tip optode has an increase detection area of 2x when compared to the single one. This means that there is an increase around 2x on sensitivity and a reduction in the gain average which improves signal quality.
Each LED emits two wavelengths (760 nm and 850 nm) with 25 mW power and has 3 mm tip.
The increase on sensitivity increases slightly the dark noise level. Taking this into consideration, for NIRSport the acquisition software (NIRStar) requires that the user chooses when using the dual tip which adjusts the thresholds for dark noise.
For the participant preparation, the smaller diameter and gap between the tips helps to separate the hair. It is also possible to rotate the optode to aid hair separation as seen in the figure below.