Bioinspired Superwettable Microspine Chips with Directional Droplet Transportation for Biosensing.

Directional droplet transportation without extra energy input remains a challenge in microfluidic biochips for clinical detections. Herein, inspired by the water-collecting behaviors on the cactus spine, we fabricate nanomaterial-based superwettable microspine (SMS) chips. The bioinspired SMS chips are capable of spontaneous and directional droplet transportation by synergistically combining geometric asymmetry and surface superhydrophilicity. Based on theoretical models, the gradient of the Laplace pressure arising from the geometric asymmetry of the SMS chip can dominate the directional transportation of the droplet, and the superhydrophilicity of the nanomaterial-based microspine can also contribute to the droplet self-transportation. The multimicrochannel SMS chips provide a simple and energy efficient technology to realize accurate detection of serum prostate-specific antigen (PSA) from prostate cancer patients, showing great potential as a biosensing platform for clinical applications. We believe that our bioinspired superwettable two-dimensional conical surface will offer effective means for the design of smart microfluidic devices and have great potential applications in multicomponent biosensing and clinical detection.