创新背景

研究人员经常使用可穿戴传感器在较长时间内收集患者的医疗数据。它们的范围从皮肤上的粘合剂绷带到器官上的可拉伸植入物，并利用复杂的传感器监测健康或诊断疾病。

这些设备包括被称为互连的扁线，以及传感器、电源和天线，用于向智能手机应用程序或其他接收器传输数据。为了保持完整的功能，它们必须与皮肤和器官一起拉伸、弯曲和扭曲，而不能产生损害回路的张力。

创新过程

为了实现低应变的灵活性，工程师们使用了“岛桥”结构。这些岛屿容纳了刚性电子和传感器组件，如商用电阻、电容器和实验室合成的组件，如碳纳米管。这些桥把岛屿彼此连接起来。它们的螺旋形和之字形像弹簧一样伸展，以适应较大的变形。

在过去，研究人员使用光刻技术建立了这些岛桥系统，这是一个多步骤的过程，利用光在半导体晶圆上创建图案。以这种方式制造可穿戴传感器需要一个干净的房间和复杂的设备。制造传感器首先要将聚对苯二甲酸乙二醇酯(PET)胶粘剂片粘在聚酯薄膜衬底上。

然后，乙烯切割机用两种切割方式将它们塑形。第一种是隧道切割，它只切开PET的最上面一层，而不伤及聚酯基板。第二种是直切式，可以把两层都切开。这足以生产岛桥传感器。

由双模式切割制造工艺制成的可拉伸“智能网格”。该装置可应用于皮肤安装的汗液提取和传感。

首先，在上部胶粘剂PET层中使用隧道切割来跟踪互连的路径；然后切割的PET片段剥落，留下图案的互连暴露的聚酯薄膜表面。接下来，整个塑料板涂上一层金（也可以使用另一种导电金属）。剩余的顶部PET层被剥离，留下一个具有明确互连的聚酯薄膜表面，以及暴露的金属开口和岛屿上的接触垫。然后将传感器元件连接到接触垫上。对于电子器件，如电阻器，使用导电膏和普通热板来固定键合。一些实验室合成的成分，如碳纳米管，可以直接应用到衬垫上而不需要任何加热。这一步完成后，乙烯切割机使用贯穿切口雕刻传感器的轮廓，包括螺旋、之字形和其他特征。

为了演示这项技术，研究人员开发了各种可拉伸元件和传感器。其中一个安装在鼻子下面，根据传感器前后之间产生的微小温度变化来测量人类呼吸。另一个原型由一系列防水超级电容器组成，它像电池一样储存电能，但释放电能的速度更快。超级电容器可以为某些类型的传感器提供电力。

创新关键点

这项新技术用乙烯切割机取代了光刻技术——一种在洁净室中制作电脑芯片的多步骤工艺。

创新价值

这种新方法将制造小批量传感器的时间缩短了近90%，同时降低了近75%的成本。大多数从事医疗设备研究的人员都没有光刻学背景，新方法使他们可以在电脑上更改传感器设计，然后将文件发送到乙烯切割机制作。新技术更简单、更快、更经济，特别是医学研究人员通常需要做一到二十多个样本时。

Innovative use of ethylene cutting machine to create wearable sensors

To achieve low-strain flexibility, the engineers used an "island bridge" structure. These islands house rigid electronic and sensor components such as commercial resistors, capacitors and laboratory-synthesized components such as carbon nanotubes. These Bridges connect the islands to each other. Their helices and zigzags extend like springs to accommodate large deformations.

In the past, researchers have built these island-bridge systems using lithography, a multi-step process that uses light to create patterns on semiconductor wafers. Making wearable sensors in this way requires a clean room and sophisticated equipment. The sensor is made by first sticking a polyethylene terephthalate (PET) adhesive sheet to a mylar substrate.

The vinyl cutter then shapes them using two cuts. The first is tunnel cutting, which cuts through only the top layer of PET without harming the polyester substrate. The second is the straight cut, which cuts through both layers. That's enough to produce an island-bridge sensor.

First, tunnel cutting was used in the upper adhesive PET layer to track the path of the interconnect; The cut PET segments then peel off, leaving the interconnect of the pattern exposed to the mylar surface. Next, the entire plastic sheet is coated with gold (another conductive metal can also be used). The remaining top PET layer is stripped away, leaving a mylar surface with clear interconnections, as well as exposed metal openings and contact pads on the islands. The sensor element is then connected to the contact pad. For electronic devices such as resistors, a conductive paste and a common hot plate are used to hold the bond in place. Some lab-made components, such as carbon nanotubes, can be applied directly to the liner without any heating. After this step is complete, the ethylene cutter uses the through-cut to carve the outline of the sensor, including spirals, zigzags, and other features.

To demonstrate the technology, the researchers developed a variety of stretchable elements and sensors. One, mounted under the nose, measures human breathing based on tiny temperature changes generated between the front and back of the sensor. Another prototype consists of a series of waterproof supercapacitors that store electricity like a battery but release it much faster. Supercapacitors can provide power for some types of sensors.