BIPOLAR.
A bipolar circuit uses two electrodes of equal size to create a dipole circuit. The bipolar circuit is the classical form of diathermic heating, in that the loss created in the dielectric is evenly dispersed between the electrodes. In electrosurgery, a high current density is applied through bipolar forceps, coagulating the small amount of tissue contained between the tips of the forceps with minimal effect on surrounding tissue. Both electrodes of the dipole are located at the site of coagulation (Fig. 1). Because the path of least resistance is the shortest distance between the electrodes, the probability of the current traveling via an alternate pathway is reduced.
Fig. 1. A bipolar circuit.
UNIPOLAR.
In unipolar electrosurgery, a small active electrode relative to the patient plate is used at the site of surgery. The high current density produced at the active electrode creates a pronounced diathermic effect, causing tissue destruction at the operative site. The patient plate's large size lowers the current density at its placement site, preventing unwanted burns. The term unipolar or monopolar is used because only one electrode of the dipole is located at the site of surgery (Fig. 2). Because the two electrodes (active and ground electrodes) and the patient's tissue form a circuit, the current's likely path is from the active electrode to the ground electrode and back to the electrosurgical generator, completing the circuit.
Fig. 2. A unipolar circuit.
Jinhua Huacheng Medical Appliance Co.,Ltd.
Manufactuer of disposable medical products: Electrosurgical pencil,grounding plate,skin stapler and ECG electrode
