On-site detection of biomarkers in biofluids found at the crime scene is critically important forensic analysis. However, it remains difficult due to the lack of portable, fast and cheap on-site analytical devices. Traditional methods including polymerase chain reaction (PCR) and electrophoresis requires complicated instrumentation and critical environment. Optical analytical methods can be affected by intrinsic adsorption of complicated sample such as serum. In response, we developed a smartphone-interfaced electrochemical chip device for on-site gender verification. The detection is based on the known difference of biomarkers (creatine kinase (CR) and alanine transaminase (ALT)) between male and female groups. Enzyme cascade reaction converted the enzyme level in biofluids to the consumption of NADH, which can be electrochemically detected by our designed electrochemical chip. Our device retained the capability of gender verification when used in serum and serum stains. The detection can be completed in 20 min. Gender verification of real samples (39 serum samples) demonstrated excellent sensitivity and specificity of this smartphone based device. (C) 2016 Elsevier B.V. All rights reserved.