Inexpensive disposable sensor platforms have the ability to revolutionize personalized cancer diagnostics. Monitoring levels of specific biomarker proteins in serum can provide further insight into a patient’s disease status enabling for physicians to diagnose and treat patients on the spot. Electrochemical sensors are among the most popular for point –of-care use due to ease of detection, low instrumentation cost, and the ability to be miniaturized and automated. A typical electrochemical cell consists of a counter, working, and reference electrodes. Miniaturization and production cost of electrodes have been improved by patterning electrodes on a substrate surface. Common methods however, are time consuming and costly therefore limiting rapid prototyping. Described here is an inexpensive commercially scalable way to integrate these electrodes on a single test chip to detect clinically relevant breast cancer biomarker Human Epidermal Growth Factor Receptor 2 (HER-2) in serum. The sensor platform consists of an inkjet printed gold nanoparticle -working 8-electrode array (WEA) and counter electrode (CE), along with an inkjet printed silver electrode that was chlorinated with bleach to produce a Ag/AgCl quasi-reference electrode (RE). The WEA featured an excellent nanostructured surface to build immunoassays. Therefore, capture antibodies were bound to a chemically modified surface on the WEA and placed into a simple microfluidic device. A full sandwich immunoassay was assembled following a simultaneous injection of HER-2, biotinlyated antibody, and polymerized horseradish peroxide labels into the microfluidic device housing the WEA. A clinically relevant detection limit of 12 pg mL^-1 was achieved in a total assay time of under 20 mins. Excellent reproducibility and sensitivity of the biosensor were observed through recovery assays preformed in human serum, containing hundreds to thousands of competing proteins. Following this rapid assay protocol these sensor platforms could easily be adapted for multiplex detection of a panel of proteins for breast cancer screening