Germanium coated silicon nanowires as human respiratory sensing device

We report on germanium coated silicon nanowires structures synthesized with metal assisted chemical etching and qualify their functionality as human respiratory sensor. The sensors were made from p-type single-crystalline (100) silicon wafers using a silver catalyzed top-down etching, afterwards coated by 50 nm germanium thin layer using a magnetron sputtering. The germanium post-treatment was performed by rapid thermal annealing at 450 and 700° C. The sensors were characterized by X-ray diffraction diffractogram and scanning electron microscopy. It is demonstrated that the sensors are highly sensitive as human breath detectors, with rapid response and frequency detectability. They are also shown to be a good candidate for human respiratory disease diagnoses.