Sakuichiro Adachi

Electroosmosis injection of blood serum into biocompatible microcapillary chip fabricated on quartz plate.

A chip which allows the detection of various human health markers from a trace amount of blood has been studied. As a goal, a microcapillary with a 30 × 30u2005μm cross‐section was fabricated using all‐dry etching technologies on a 2 × 2u2005cm SiO2 chip. The coating of the biocompatible 2‐methacryloyloxyethylphosphorylcholine (MPC) polymer on the inner quartz wall of the microcapillary demonstrated a sufficiently long adsorption suppression of proteins in the serum on the quartz surface, while rapid stopping occurred for serum injected into the microcapillary with a bare quartz surface. The latter rapid stopping corresponded well to fast electroosmosis flow due to the negatively increasing zeta‐potential by the adsorption of proteins on the quartz surface. The electroosmosis pump arranged a downstream of the microcapillary was also developed to inject serum into it. As a preliminary application, a given concentration‐standard solution was injected into the ion‐sensitive field‐effect transistor (ISFET) embedded in the chip, employing the electroosmosis pump arranged downstream of the sensor position. Hence, the pH and Na+ and K+ cation concentrations were measured.

Low-Voltage Electroosmosis Pump and Its Application to on-Chip Linear Stepping Pneumatic Pressure Source

Low-voltage EOF pumps which consist of narrow gap channels and cascade configuration were microfabricated on quartz chips. A pressure of 500 rnmH2O (∼5000Pa) was obtained at 40V using a 120nm gap single stage pump, and it was confirmed that the pressure increase with cascade stage numbers without accumulating voltage. For an example of applications of these pumps, a linear stepping actuator was demonstrated as a pressure source of stand-alone pneumatic-driven microfluidics chips.

Development of elemental technologies for fabricating the health care chip

To create the health care chip, which is an intelligent micro analytical system to detect various human health markers from a small droplet of blood, we are now developing a measurement system of the markers in electroosmosis injected serum employing chemical sensors conjugated to the microcapillary made by a quartz plate. The complete system requires a painlessly collection of the blood by a needle, separation of serum from such small amount of blood, biocompatibility of the capillary inner surface and implementation of these technologies to the real health care chip. This paper reports recent studies regarding these elemental issues.

Glucose Measurement in Blood Serum Injected by Electroosmosis into Phospholipid Polymer Coated Microcapillary

The “health care chip” which enables us to detect various human health markers has been studied. Amperometric and potentiometric ISFET sensors were arranged on a upstream flow path of a microcapillary of 30x30,μ m crosssection fabricated by all dry etching processes onto a 2x2 cm SiO2 chip. The capillary inner wall were coated by a biocompatible 2-methacryloyloxyethylphosphorylcholine (MPC) polymer to surpress to adsorption proteins on the bare quartz wall. The serum was injected into the capillary by the electroosmosis pumping which was operated by applying voltage in the downstream region of the capillary to avoid the electric field effect on electro-chemical sensors. The MPC coating which reduced protein adsorption on the capillary inner wall led to smooth injection of the serum in contrast with the uncoated case. Measurements of pH, and concentration of Na+, K+ and glucose were sucessfully performed by the pumping of the serum injected the electric-field-free region.

Biochips aiming at advanced medical treatment

Publisher Summary This chapter aims at “the advanced medical treatment fitted to individuals” from the current medical treatment carried out by “the greatest common measure” that the same medicine is provided to every individual. The healthcare chips are planned to enable one to check daily health condition from analyzing a trace amount of whole blood collected by a painless needle. The semiconductor micro/nano fabrication and volume production technologies are indispensable for this goal. Close contact with other scientific and technological research fields allows a person to design one chip, which can perform the present clinical inspection functions. If the chip measures many markers at the same time, then one can check easily and rapidly health and disease conditions at home by referring a lot of databases stored in the clinic centers through IT network. This demonstrates a fusion of the electronics and biotechnologies, which have developed independently.

Electrophoresis Velocity Measurement of Lymphocytes Under Suppression of pH Change of PBS in Microcapillary

pH changes in PBS(Phosphate Buffer Solution) in a microcapillary including reservoir and waste were measured using embedded ISFETs (ion sensitive field effect transistor). The pH change was measured in the capillary suppressed by inserting salt bridges near the reservoir, thus allowing to measure electrophoresis velocity of lymphocytes in the capillary