The apparatus comprises a vacuum tank with a front-mounted collection means thereunder The collection means is a V-shaped scraper with a height adjustable suction inlet at the apex thereof. The method comprises reacting a dry etch plasma with a layered microstructure; the layered microstructure having an etch mask, a sacrificial layer and a device layer arranged between the etch mask and the sacrificial layer. The assay is based on a sample selected from the group consisting of body secrete, sputum, blood, urine, uterus secretes and cells. The contact pad coupled to the circuit block is configured to swing from a voltage of the negative rail to a voltage of the positive rail.