Start typing and press Enter to search

This website does not support Internet Explorer. For a correct visualization we recommend to use Microsoft Edge or Google Chrome.

新闻

Measurements of the initial deflection of a nano pressure sensor for biological applications

未分类
| Other articles

巴塞罗那微电子研究所 (IMB) 是国家微电子中心 (CNM) 在巴塞罗那的所在地,也是西班牙研究理事会的成员机构。除了微技术和纳米技术、组件和系统教育和培训外,IMB-CNM 还专注于基础和应用研究与开发。我们的使命是扩展此领域的可用知识,助力实施基于这些技术的解决方案和新产品,从而解决当今社会面临的种种挑战。

With this technique, it’s possible to obtain a fast and non-destructive measure of the deflection of the released membrane before and after sealing

In the fabrication of nano pressure sensors for biological applications, the sacrificial layer etching and the sealing of the two membranes separated by a vacuum gap to form a Fabry–Pérot resonator is critical.

Knowing the exact timing of the initial deflection of the membrane after the fabrication process is also key.

cs2 CNM - nano pressure sensor 1
Figure 1. SEM image of the fabricated pressure sensors (Bar scale 1 µm)

The pressure sensor is a 6×10 µm chip comprised of a mechanical sensor defined by two polysilicon membranes separated by a vacuum gap, and an optical reference area.

The membranes act as parallel reflecting mirrors, constituting a Fabry–Pèrot resonator that is partially transparent for some wavelengths. An external pressure P deflects the membranes and changes the gap. This device was designed to measure pressure changes inside the different components of a living cell

cs2 CNM - nano pressure sensor 2
Figure 2. Device with a non-collapsed membrane (top) and a device with a collapsed membrane (bottom) (Bar scale 1 µm)

Currently, membrane deflection measurements are carried out using Scanning Electronic Microscopy (SEM) before being internalized, but in the SEM, samples must be under vacuum pressure which may alter their initial state.

Using a Sensofar optical profiler we were able to measure, in a quick and non-intrusive way, the deflection of the membranes after manufacturing. The dimensions of the chip are only a few microns, but the curvature of the membrane is closer to tens of nanometres, so it’s necessary to use a high magnification lens.

cs2 CNM - nano pressure sensor 3
Figure 3. Profile analysis of several pressure sensors
cs2 CNM - nano pressure sensor 4
Figure 4. 3D topography of a pressure sensor’s array before the release from substrate

With this technique, it’s possible to obtain a fast and non-destructive measure of the deflection of the released membrane before and after sealing to check if membranes have collapsed. Previously, they had to be inspected by SEM which produced changes in the deflection of the membrane due to the vacuum and the value of the deflection was not as reliable.

These measurements were obtained with a Plµ 2300 using a confocal technique with a 100X brightfield objective. Sensofar equipment provides non-contact 3D surface profilers based on three technologies: Confocal, Interferometry and Focus Variation techniques. With Sensofar equipment, high-resolution measurements can be made quickly and in a non-destructive way, and user-friendly software provides technical support as needed.

cs2 CNM - nano pressure sensor 5
Figure 5. 3D topography of a 6x10 µm released pressure sensor

Related products

Leave a comment

cs6 USC - laser for microfluidic Hcs7 KIT - OLED H