All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
The need for the woman to preserve her chastity is given priority over her need to eat and drink. So, the husband should satisfy his wife's sexual need with kindness as he should satisfy her need for expenditure.
Now if the husband travels abroad for work or other purposes, he should come back to his wife every six months as most of the time, the woman cannot stand being away from her husband for a period exceeding six months. This is what the Sharee’ah orders. As for masturbation (by hand or other means), it is forbidden for both the man and the woman and it is a form of transgression. Allah Says (what means): {And those who guard their chastity (i.e. private parts, from illegal sexual acts).} [Quran 23: 5]
From the above, we say that it is unlawful for you to buy this device for your wife because doing so is considered a help in sin and Allah Says (what means): {…but do not help one another in sin and transgression. ….} [Quran 5: 2]
Allah Knows best.