Therapeutic microsystems are designed to alleviate certain symptoms and help in the treatment of a disease. In this category, we will describe two such microsystems. The first one is a drug delivery microchip designed to administer small quantities of potent drugs upon receiving a command signal from the outside. The second device is a passive micromachined glucose transponder, which can be used to remotely monitor glucose fluctuations allowing a tighter blood glucose control through frequent measurements and on-demand insulin delivery (pump therapy or multiple injections)
Figure 10.5 shows the central component of the drug delivery microchip [52, 53]. It consists of several micro-reservoirs (25 nl in volume) etched in a silicon substrate. Each micro-reservoir contains the targeted drug and is covered by a thin gold membrane (3000 A), which can be dissolved through the application of a small voltage (1V vs. SCE), Figure 10.5. The company marketing this technology (MicroCHIPS Inc.) is in the process of designing a wireless transceiver that can be used to address individual wells and release the drug upon the reception of the appropriate signal . Another company (ChipRx Inc.) is also aiming to develop a similar microsystem (Smart Pill), Figure 10.6 . Their release approach however is different and is based on conductive polymer actuators acting similar to a
FIGURE 10.5. MicroCHIP drug delivery chip (top), a reservoir before and after dissolution of the gold membrane (bottom) .
Control Circuitry Biosensor mm
Drug Release Holes
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