Development of in-vivo pH Measurement Chip in Digestive System

人们非常关注用于医疗诊断和治疗的“饮用”或“体内”生物芯片的开发。为了创造一种药物输送系统（DDS），通过检测消化系统中目标的pH值来释放药物，我们还计划开发一种“体内”pH传感芯片。为了实现该芯片，必须开发天线、低压驱动泵、电容式电池以及它们的三维集成。为了提高从外部线圈向内部线圈传输数据的S/N比，研究了片剂结构和胶囊结构作为内部线圈。所研究的片剂结构的尺寸为直径4.5mm和高度4 mm。囊体直径2.5mm，长15 mm。通过计算两种结构的耦合因子，发现片剂结构比胶囊结构更适合。由于传输距离短于信号波长，因此传输信号由电通量和磁通量承载。关于渗透特性，我们采用电磁耦合传输而不是电磁波传输。脉冲间隔调制比幅移键控、频移键控和相移键控具有上级性能。采用0.18mm硅CMOS工艺，研制了一种有源区面积为150 × 150 μm^2、工作速率为kbps/Mbps的小型通信芯片。该通信芯片在108.48MHz时的功耗为0.6mW。我们开发的DDS能够控制药物的释放时间。并对药物在胃中的漂浮和滞留系统进行了研究.药物释放的时滞和速度可以通过等离子体干燥工艺进行表面处理来控制。

Much attention is paid for the development of "drinking" or "in-vivo" biochips for medical diagnostics and treatments. To create a drug delivery system (DDS) releasing a medicine by sensing the pH of the target in the digestive system, we also plan to develop an "in-vivo" pH sensing chip. To realize the chip, an antenna, a low voltage driven pump, a capacitor type battery and their three-dimensional integration has to be developed. To improve the S/N ratio of transmitting the data from the external coil to the internal coil, a tablet structure and a capsule structure were investigated as the internal coil. The size of the investigated tablet structure is 4.5mm in diameter and 4 mm in height. The size of the capsule structure is 2.5mm in diameter and 15mm in length. From calculating the coupling factor in both structures, it is found that a tablet structure is suitable better than a capsule structure. The transmission signal is carried by electric and magnetic fluxes because the transmission distance is shorter than the signal wavelength. With regard to permeation characteristics, we adopted the electromagnetic coupling transmission rather than the electromagnetic wave transmission. The pulse interval modulation is superior to amplitude shift keying, frequency shift keying and phase shift keying. A small communication chip with an active area of 150 x 150 μm^2 allowing kbps/Mbps has been developed using 0.18mm Si CMOS(complementary metal-oxide semiconductor) process. The communication chip showed consumption power of 0.6 mW at 108.48MHz. We developed DDS enabling to control the time of releasing a medicine. And we also studied the system a medicine floats and remains in stomach. The time lag and the speed of releasing a medicine can be controlled employing surface treatment by plasma dry process.