Scientists have developed a small pill for patients to swallow. It mixes synthetic biology and electronics to find bleeding in the stomach and other parts of the digestive tract.

The biological part of the pill uses bacteria engineered to light up when it comes in contact with heme， the iron-containing molecule in blood. The electronic side includes a small light detector， computer and computer chip. It also has a battery to provide power and a transmitter that sends information to a cellphone or computer.

“A major challenge for sensing in the gastrointestinal tract is， the space available for a device is very limited，”said electrical engineer Phillip Nadeau. Nadeau and other engineers using very low-power electronics to make the pill. It measures about 3 centimeters long by 1 centimeter wide. The pill is still too big to swallow， but Nadeau says it likely can be engineered to a third that size.

The engineered bacteria are in areas covered by a membrane. This thin， soft material lets small molecules in， but does not let the organisms out. The researchers say the bacteria can be engineered to die if they accidentally leak from the pill. Future models may just use the most important enzymes instead of whole bacteria.

In lab tests， the pill successfully identified pigs fed small amounts of blood from those not given blood. The pill has not been tested on human beings， but the team hopes to do so in the next year or two.

Researchers believe that， once ready， the final product would sell for tens to hundreds of dollars. And they say the same method could be used to identify markers for disease or to find chemicals in the environment.

科學家开发出了一种让病人吞服的小药片。这种药片是将合成生物学和电子学相结合而研制出来的，目的是发现胃内及消化道其他部位的出血。

药片的生物学部分使用了一种基因工程菌，这种细菌接触血液中含铁的血红素时会发光。药片中的电子学部分包括一个小型光探测仪、计算机和计算机芯片，还有一块电池提供动力，以及一个发送信息至手机或计算机的发射机。

“胃肠道传感所面临的主要挑战是能够容纳一个设备的空间极其有限。”电气工程师菲利普·纳多说。纳多和其他工程师使用非常小功率的电子设备来做这种药片。药片的尺寸大约三厘米长，一厘米宽。这药片还是太大了，无法吞下。但是纳多说有可能把药片的尺寸缩小到原来的三分之一。

这种基因工程菌处于被一层薄膜覆盖的区域。这种柔软的薄材料可以让小分子进来，却不能让生物体出去。研究者说，这种细菌可以通过基因工程而被改造为：如果它们意外地从药片里逃出来，那么只有死路一条。未来的模型可能会仅使用重要的酶来代替完整的细菌。

实验测试表明：这药片能够成功区分被喂过少量血液的猪和没有被喂过血液的猪。目前，对药片还没有进行过人体试验，但研究小组希望在未来的一两年内用人体做试验。

研究者认为，一旦一切就绪，最终产品的价格将在几十美金到几百美金。他们还说，可以使用同样的办法来识别疾病标记物或者发现环境中的化学物质。

（注意斜体句子的译法）