SH-SAW Biosensor for Point-of-Care

1. Background, Motivation and Objective : Point of care testing (POCT) which is defined as diagnostic testing at or near the site of patient care has been required for future home healthcare. There are various important requirements for the biosensor platform for POCT, such as portable, cost per test, maximum achievable sensitivity and specificity, ease of use and wireless connectivity. 2. Statement of the Contribution/Methods : This paper describes an immunoassay-based shear horizontal surface acoustic wave (SH-SAW) biosensor for POCT. A 250MHz delay-line SH-SAW sensor device was designed on 36Y-90X quartz substrate and fabricated. Three attractive design techniques for SH-SAW biosensors are used. The first is a reflection type design technique to reduce the device size. The reflection type sensor device has one input/output IDT and a grating structure at the end of the device. The second is a reference channel design technique to compensate temperature drifts and viscosity variations of the liquid samples.The third is a technique using “membrane” such as paper or nitrocellulose on the sensor surface of the SH-SAW device. Although a membrane is placed on the surface of the sensor device directly, the sensor device can work as well as a conventional sensor device without membranes. The membrane techniques can provide some attractive functions, such as keeping sample solutions on the sensor surface, filtering the speci-men (separation of blood plasma) and having gold conjugated-antibodies inside. Figure 1 shows a two-channel reflectiontype SH-SAW biosensor device with a mem-brane.