Sensors and instruments
Microtechnology for our planet and space
Here, microtechnology is used to either minituaturise standard instruments, making them up to 1000 times smaller, or to enable measurments with still unused techniques, or to measure in harsh environments. Some examples:
- Optogalvanic spectroscopy
- Micromagentometers
- Sensors for high temperatures
Optogalvanic spectroscopy
Measurements of trace gases and isotopic ratios are important tools when studying the history and evolution of the solar system. A majority of past planetary exploration missions have carried different kinds of spectrometers to perform such measurements, and the demand for this kind of instruments is expected to continue in future missions, although they will have to meet more demanding requirements in terms of mass, power consumption, integrability and sensitivity.
This research program revolves around a laser-based IR spectrometer, more precisely one based on the optogalvanic effect, which is capable of both trace-gas sensing and isotope-ratio measurements. Such an instrument can be robust yet extremely sensitive – two promising features when aiming for space applications – and can be used to study a wide variety of molecules. One of the major aims of the program is to study the possibility of creating a miniaturized version of the instrument by employing microsystems technology. A miniaturized optogalvanic spectrometer would not only be small, but also power efficient, and, hence, ideal for future planetary exploration missions to, e.g., Mars, Venus, the Moon, comets, and the moons of the Jupiter and Saturn.
In more concrete terms, the program aims at investigating how a novel optogalvanic sensor cell, invented by the applicant, can be combined with a quantum cascade laser, into a powerful, yet versatile platform for optogalvanic spectrometry of trace-gases and isotope ratios, and how this platform can be qualified for space.
Magnetometers
The aim of the project is to investigate how magneotresistive sensors can be applied to space. These sensors are based on the same technology that is used to read the information of a computer hard drive, and can be made extremely small. Our smallest sensors are only a fraction of a millimeter, and together with some electronics they can be integrated in to a complete system for magnetic field measurements – a magnetometer – well suited for use in space.
The question of why such an instrument is should be launched into space is of course relevant. Most people know that Earth has its own magnetic field, but fewer know that this field creates a magnetic bubble that protects us form harmful radiation primarily from the Sun. However, close to the magnetic poles the bubble is weaker, and sometimes cosmic radiation slips through and reaches the atmosphere, which causes what we know as an aurora. Even though most of us experience the aurora simply as an exciting celestial phenomenon, it actually can be quite harmful, especially for different kinds of electrical systems. Apart from causing power failures, the strong magnetic fluctuations associated with auroras have been found to affect the safety systems of railroads and cause problems for both airplanes and satellites. Hence, our modern society requires a good understanding of the interactions between Earth’s magnetic field and space.
We have developed several different types of magnetometers, one of which made its maiden journey on the Vietnamese satellite F-1 in 2011 (picture), and another one is currently being prepared to follow the Japanese satellite RISESat into space
Sensors for high temperatures
En av bristerna hos kisel, som är det mest använda materialet i mikrosystemteknik, är att det mjuknar vid höga temperaturer. I sig behöver detta inte innebära problem, men om kiselbaserade komponenter samtidigt utsätts för mekanisk påverkan eller, vilket alltid är nödvändigt, innehåller också andra material som skapar interna spänningar, förstörs komponenten eller åtminstone förloras prestanda. Det medför att en rad intressanta och angelägna behov inte kan tillfredsställas. Till exempel kan inte vulkanologer använda sig av konventionella mikrosensorer för på-platsen-mätningar i aktiva vulkaner. Och inte heller finns det bra alternativ för den som behöver mäta tryck, temperatur och gasflöden i jetmotorer eller andra förbränningsmiljöer.
Avdelningen studerar och utvecklar därför komponenter i mer beständiga material, till exempel zirkoniumoxid och aluminiumoxid. Det är ett mödosamt arbete som ofta kräver att kiselteknikens mogna processteknik måste överges och helt nya verktyg tas fram innan man ens har komponenter att studera.
ÅSTC forskar på temperatur-, tryck- och flödessensorer för temperaturer kring 1000°C. Inte sällan råder god synergi med forskningen på raketmotorer i mikroskala där komponenterna integreras i mikrofluidala system för att dessa nyckelparametrar ska kunna mätas kontinuerligt under drift. I ett annat fall integreras de i provhanteringssystem där ett prov ska förbrännas och analyseras spektroskopiskt.
Figuren visar ytterligare ett exempel. Där är sensorn försedd med en antenn så att ett tryck på många bar kan läsas av trådlöst vid höga temperaturer. På så sätt undviker man problem som uppstår i anslutningar och genomföringar.