This study presents the design, fabrication, and assembly of a microfluidic chip with embedded electrical traces, produced through injection molding, to enable electrochemical diagnostics in small liquid volumes. Traditional PCB-based electronic devices face limitations in compactness and sealing reliability, particularly for lab-on-a-chip applications where fluids must interact with sensors without compromising electrical components. To address this, we employed in-mold electronics (IME) technology to integrate electrical traces directly within the microfluidic structure, eliminating the need for a separate PCB and enhancing design flexibility and durability. The microfluidic chip comprises microchannels, fluidic ports, and embedded electrical traces that transmit signals from a sensor pad through a mechanical interconnection facilitated by L-shaped cantilever structures. The microchannels, designed to prevent leakage, guide the sample to the reaction site. Electrical traces were fabricated using a blanking process and assembled into an injection mold where they were encapsulated within the polycarbonate microfluidic plate. The design of the L-shaped cantilever structure ensures reliable electrical contact through mechanical pressure, without the need for soldering, while a double-sided adhesive film seals the microfluidic channels to the sensor pad plate. Experimental tests confirmed that the microfluidic chip achieves both effective channel sealing and secure electrical interconnection, suitable for applications requiring electrochemical or impedance-based biomarker detection. This work demonstrates the feasibility of injection-molded, electrical trace-embedded microfluidic chips as diagnostic platforms for biochip and lab-on-a-chip applications, offering a promising approach for compact, reliable electrochemical diagnostics.