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HOME > Encouragement of Learning > The Charm of Diamonds goes beyond Jewelry -The Highly Sensitive Sensor Diamond Electrode

The Charm of Diamonds goes beyond Jewelry -The Highly Sensitive Sensor Diamond Electrode

EINAGA, Yasuaki (Ph.D)

This is a diamond created at our research group. It is a highly sensitive sensor.

Diamonds will grow in this plasma.

Arsenic and other things are analyzed in water by using diamond electrode.

The grey thing held by the tweezers does not have “eternal shine”… (In fact, it is grey!) However, this is a genuine “diamond”.
This dark, board-shaped thing in which micron-sized diamond particles are deposited can actually function as a highly sensitive sensor that can measure uric acid and glucose in blood and urine, and also the concentration of arsenic, metal and environmental hormones in underground water instantly, correctly, detecting even the tiniest amounts. This is the “diamond electrode”, a brand-new material that is currently in the spotlight.

At our research group, we make this kind of diamond using microwave plasma CVD. For the source, we use gas or a solution containing carbon. Alcohol also can be used. We introduce these sources into the plasma (figure 2), then, the diamond is deposited on the substrate.

A technique called high-pressure synthesis is often employed in order to synthesize artificial diamonds, but because this device needs to recreate conditions the same as inside the earth with an atmospheric pressure of ten thousand and temperatures of 2000 degrees centigrade the device is huge, taking up a whole room. However, the CVD device in our research group occupies only space of one tatami mat. Furthermore, when switched on in the morning, high sensitive sensor diamond can be completed by the evening. Other than the size, the way this diamond differs from diamonds used in jewellery is that it shows electric conductivity. When the source is mixed with boron (doping), conductive diamonds will be completed during the manufacturing process.

This diamond electrode has a most useful electrochemical property such as wide potential window and very low background current. This means that when inputting electric voltage into water (or in fact blood, urine, underground water etc) and reading the current, it is possible to accurately measure the level of uric acid, glucose or the concentration of arsenic, metal or environmental hormones.

We are enjoying furthering this fascinating research, in the knowledge that one day soon it will play an important part in medical establishments and institutions carrying out environmental analysis.