Amino acids, essential compounds of life, are found in a variety of foods and pharmaceuticals, presenting a special importance for humans. The intake of amino acids contributes to the treatment of disorders such as: anxiety, depression, ADHD, insomnia etc. Prevention of these diseases can be achieved by using modern amino acid detection devices, such as biosensors. Simplicity, portability, fast response time, high specificity and sensitivity are just some of the advantages of these versatile devices. Because biosensors for the detection of amino acids involve in the preparation process the use and immobilization on the electrode surface of an enzyme, in the case of detection of phenylalanine, tyrosine and tryptophan, the researchers most frequently used laccase, tyrosinase, L-amino acid oxidase. These enzymes have improved the performance of biosensors, obtaining low detection limits, high reproducibility, and long-term stability. The methods that showed increased efficiency for the detection were the electrochemical ones, respectively cyclic voltammetry, differential pulse voltammetry and linear sweep voltammetry.