The application of superelastic SMAs in less invasive haemostatic forceps

A new application of stress-induced transformation of superelastic shape memory alloys (SMAs) for atraumatic haemostatic forceps has been proposed. In conventional haemostats the pressure on the clamping jaws directly reflects the passive response of biological tissues, exhibiting an exponential increase during grasping, thus making control within a safe range difficult. The proposed new concept of haemostatic forceps is to embed superelastic shape memory alloys in conventional forceps and to limit the clamping pressure of the forceps within a safe range via the unique stress–strain characteristics of superelastic SMA during its stress-induced transformation. In the present paper, the potential of such an idea for practical use is demonstrated with a newly developed prototype. It is shown that the critical pressure was successfully controlled in the range of 200–800 mm Hg, where superelastic SMA wires of 0.2 and 0.3 mm in diameter were employed.