Healthcare Chip for Checking Health Condition from Analysis of Trace Blood Collected by Painless Needle

A healthcare chip for checking the health condition at home has been studied based on the analysis of a trace amount of blood collected by a painless needle. A microcapillary as the main component for the blood flow was fabricated by molding its reverse pattern made of a quartz plate on a cheap and disposable poly(ethylene terephthalate) (PET) plate with an area of 2 cm × 2 cm. The painless needle was fabricated by polishing the tip of a stainless steel tube (SUS) with a 100 µm diameter at an angle of 10 degrees using chemical mechanical polishing (CMP) and subsequently finishing it by electropolishing. Coating the 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer on the inner surface of the capillary effectively suppressed the adsorption of corpuscles. A quartz electroosmosis flow pump embedded in the PET plate introduced the blood into a U-shaped capillary through the needle and the blood was centrifugally separated into the corpuscles and plasma on the chip. The plasma was then conveyed to ion-sensitive field-effect transistors (ISFETs) set on the capillary and the Na + and K + ion concentrations were measured with high selectivity. Finally, a series of chip operations from blood collection to measurements of the pH, Na + and K + ion concentrations was demonstrated.