The Harmonic scalpel is a cutting instrument used during surgical procedures to simultaneously cut and coagulate tissue.
The Harmonic brand is manufactured and distributed by Ethicon Endo-Surgery a subsidiary of Johnson & Johnson.
The instrument is similar to a Bovie, but superior in that it can cut through thicker tissue, creates less smoke, and may offer greater precision. However, the harmonic scalpel is not as easily maneuverable as the Bovie, and takes longer to cut and coagulate tissue. Additionally, while a Bovie can be used to coagulate bleeding tissue at any time, the Harmonic scalpel only coagulates as it cuts.
The 'Harmonic scalpel" causes less lateral thermal damage than the "Bovie".
Whereas a Bovie performs its action via an electrical current (and production of heat), the Harmonic scalpel cuts via vibration. The scalpel surface itself cuts through tissue by vibrating in the range of 55,500 Hz. The vibration cuts through the tissue and seals it using protein denaturization, rather than heat. A good analogy is whisking an egg white; denaturation of the protein by vibration rather than heat.