A trigate field effect transistor is a transistor along with three gates that wraps three of the four sides of a substrate. A trigate junction less transistor (TGJLT) is a kind of field effect transistor that works in the absence of conventional p-n junctions found in conventional transistors. The trigate junction less transistor characteristics a 3-D gate structure that surround around the channel on three sides. In this paper, comparison analysis of field effect transistor including conventional trigate field effect transistor and trigate junctionless field effect transistor device-based biosensor has been investigated. The main focus toward this work is to utilize permittivity of conventional trigate and trigate junctionless field effect transistor device-based biosensor for sensing the neutral biomolecules. Performance parameters include threshold voltage, subthreshold swing of the conventional trigate and trigate junctionless field effect transistor devices are presented. In this work in the end, the characteristics of device is calculated by its sensitivity. It is observed that the sensitivity of trigate junctionless field effect transistor device for different biomolecules having dielectric constant, k is more efficient than conventional trigate field effect transistor devices. The preferred device has been achieved through simulation from a 3-D device simulator, the visual TCAD from Cogenda Pvt. Ltd.