I am a doctor. Part of my job is to prescribe medical devices to patients. The companies that sell these devices offer me some money to prescribe their own products. Is this money Halal, considering that I do not prescribe except the devices that benefit the patients and the companies do not increase the price of the device beyond its regular one?

Praise be to Allah, the Lord of the World; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.

If a doctor prescribes medical devices or medicines of some company that gives him some money for such work, and these devices and medicines are equal to other companies' products in quality and price, then there is no objection to receive such money, which in fact is a form of commission.
From the point of view of Fiqh, a broker is a middleman who acts between a seller and purchaser to facilitate business transactions. Such work is legal according to the Maliki school of thought and others. Also, such legality is reported from Ibn 'Abbas , Ibn Sireen and al-Bukhari .
On the other hand, if such medical devices and medicines, that are prescribed by the doctor, are less in quality or dearer in price than the other companies' products (of the same kind), then it is Haram for him (doctor) to receive any commission.
In addition, such work contradicts the nature of a doctor's profession that is based on mercy, advice and sympathy with the patient. In reality, this constitutes a form of cheating about which the Prophet (Sallallahu Alaihi wa Sallam) said: "Whoever cheats is not of my followers" . [Reported by Imam Muslim ].
Here, we add that the company is also a partner in cheating and in sin with the doctor.
The Prophet (Sallallahu Alaihi wa Sallam) said: "Allah has cursed the briber and bribee" . [ Ahmad and al-Tirmizi ].
Allah knows best.