The novel DC-AC inverter topology with high frequency isolation transformer consists of an input DC-DC converter with high frequency isolation transformer and an output full-bridge unfolding converter with four transistors provides the output AC voltage from a DC source. Also provided herein are methods of eliciting an immune response in a subject using the antigen-presenting platelets described herein. The product, system and method can be applied to various industries, including, power generation, petro-chemical, manufacturing and refining facilities. Then, the solder bumps are formed on the pins of the devices so that the devices are fixed on the printed circuit board. Each of the plurality of blocks included in at least one of the block rows includes at least three closed grooves including at least one first closed groove and at least one second closed groove.