This paper presents a new field-effect based sensor for biosensing applications. The sensor composed of a new structure that is based on the junction field-effect transistor or JFET which is a well-known electronic transistor. To prepare the JFET for biosensing and solution-based sensing, the p-type JFET is opened from one side (the n-type layer is removed) that allowing applying a solution containing biochemical substances on top. The opened-gate area consists of silicon with a very thin layer of SiO2 which is naturally grown on silicon when is exposed to the environment. The p-type channel length between a source and drain is about 100 µm and its thickness is 1.6 µm with 1000 µm wideness. A common source design is introduced containing seven channels that further improve the sensing area (≈ 0.7 mm2). To demonstrate the biomolecular sensing capability of the open-gate junction field-effect transistor (OG-JFET), dried-DNA is used. An almost linear response is resulted showing a sensitivity of 30 µA/DNA-Concentration (ng/nL).