This paper presents the system design of a real-time hyperspectral imager based on tunable Fabry-Pérot interferometer (FPI) filter technology. This passive hyperspectral instrument is able to capture spectral data at a rate corresponding to video-like image feed. The instrument is designed to be suitable for handheld operation as well as for missions carried out using uncrewed aerial vehicles. The frame rate of individual spectral channels of an FPI-based camera, and subsequently the acquisition speed of hyperspectral data, depends on the actuation speed of the FPI filter, exposure time of the sensor, data transfer rate, and all delays between the consecutive operations. In order to minimize the delays when switching between the spectral channels, the large FPI of this instrument is enclosed in a low-pressure housing to reduce air resistance, which would otherwise slow down the mechanical movement of the filter. As various applications require different sets of wavelengths and a variable number of spectral channels to be recorded, the imager enables selecting the desired wavelengths programmatically from within the complete spectral range of the instrument. FPI-based hyperspectral cameras produce a full two-dimensional image for each spectral channel. The spatial information contained in the images may be used to compensate for any desired or undesired movement of the imager. The spatial information available for individual channels can also be used for data analysis, and it enables employing conventional machine vision algorithms for example to detect and track the objects of interest.

The MOEMS Fabry-Perot interferometer (MFPI) based hyperspectral cameras have the advantage of being low cost and highly compact, but the performance characteristics determine if particular device can be used in given application. This paper describes the performance test results of exceptionally compact cubic-inch sized VNIR hyperspectral camera. This camera prototype was developed in a project supported by European Space Agency (ESA) and its long-term goal of this project was to develop reliable, compact and lightweight hyperspectral camera for space exploration vehicles, such as drones, landers and rovers. The camera operates in 650 nm - 950 nm range and the field of view is ca. 12.5° × 10° with image size of 640 × 480 pixels. The prototype was tested for operation in space environment. This involved test in a thermal vacuum chamber as well as a vibration test. The MFPI, developed by VTT, was also separately tested in near vacuum to evaluate its actuation speed and resonance characteristics. In addition to environmental tests, the camera completed wavelength and temperature calibration. The data acquisition speed and spectral characteristics were also determined. The results of these tests and other procedures are presented in this paper.

VTT has previously developed Fabry-Pérot interferometer-based hyperspectral cameras which have been fixed focal length cameras. In some applications it would be beneficial to have zoom capability to first search the target and then zoom in to the target to collect the data. This paper describes hyperspectral camera design with zoom optics and first test result of the camera. Hyperspectral camera has two operation modes; wide mode and tele mode. Optics design is done so that only one lens group need to move which makes mechanics and operation of the camera simpler.

Recently developed tunable MEMS Fabry- Perot interferometers based on Ag thin-film mirrors[1] have enabled building highly miniaturized spectral imagers covering almost the complete VNIR wavelength range. The level of miniaturization required by modern smartphone industry has created extremely compact, high performance electronics and camera technologies and by utilizing these technologies together with the novel MEMS FPI’s, it is possible to create extremely compact spectral imagers while still achieving good performance. This paper presents a spectral imager design that can be fit inside an envelope of 1 cubic inch (25.4 × 25.4 × 25.4 mm3 ) and it will be capable of recording images at freely selectable wavelengths within the range of ca. 650 nm - 950 nm. The imager field of view is ca. 12.5° × 10° and the image size is 640 × 512 pixels. Nominally the imager will be focused from ca. 0.5 m to infinity, but with additional optics it is possible to use the imager as a microscope. The compact size of the imager allows the easy integration to almost any available platform, including small drones, nanosatellites or planetary rovers, where small size is essential. It is also possible to integrate the imager to handheld devices, so the potential field of applications will be extensive.

Biosensors detect signals using biological sensing components such as redox enzymes and biological cells. Although cellular versatility can be beneficial for different applications, limited stability and efficiency in signal transduction at electrode surfaces represent a challenge. Recent studies have shown that the Mtr electron conduit from Shewanella oneidensis MR-1 can be produced in Escherichia coli to generate an exoelectrogenic model system with well-characterized genetic tools. However, means to specifically immobilize this organism at solid substrates as electroactive biofilms have not been tested previously. Here, we show that mannose-binding Fim pili can be produced in exoelectrogenic E.coli and can be used to selectively attach cells to a mannose-coated material. Importantly, cells expressing fim genes retained current production by the heterologous Mtr electron conduit. Our results demonstrate the versatility of the exoelectrogenic E.coli system and motivate future work that aims to produce patterned biofilms for bioelectronic devices that can respond to various biochemical signals.

Small, tunable MEMS Fabry-Perot interferometer (FPIs) have recently been demonstrated to enable hyperspectral imaging in mobile devices, so far using Bragg reflector mirror technologies, which however limit the device tuning range. This paper presents the realization of a novel MEMS FPI structure based on Ag thin film mirrors (AgMFPI), which allows tuning the entire visible - very near infrared (VNIR) wavelength range (for example 450 - 900 nm) with one single component. The characterized transmission of the components is 12 - 45% with full-width-half-maximum values (FWHM) between 11 - 18 nm using 2 mm optical aperture, while using 3 mm optical aperture results in FWHM values of 12 - 20 nm. A very compact hyperspectral imager can thus be built to cover this spectra by combining this AgMFPI and a typical RGB type of image sensor.

This paper presents a novel miniaturized hand-held hyperspectral imager for VNIR range of λ = 600 – 900 nm based on MEMS Fabry-Perot interferometer (MFPI) technology. In recent years, tunable MFPI optical filters have been utilized to demonstrate sensors for mobile applications, including CO2 smartphone sensor for mid infra-red region and hyperspectral iPhone for visible spectrum. This hand-held sensor module targets the VNIR range in order to enable food sensing, while utilizing low-cost camera technology to enable potential volume scalability for future sensing applications. The sensor module is wirelessly connected to a mobile device, which enables further application algorithms development and cloudbased solutions.

This paper demonstrates a mobile phone-compatible hyperspectral imager based on a tunable MEMS Fabry-Perot interferometer. The realized iPhone 5s hyperspectral imager (HSI) demonstrator utilizes MEMS FPI tunable filter for visible-range, which consist of atomic layer deposited (ALD) Al2O3/TiO2-thin film Bragg reflectors. Characterization results for the mobile phone hyperspectral imager utilizing MEMS FPI chip optimized for 500 nm is presented; the operation range is lambda = 450 - 550 nm with FWHM between 8 - 15 nm. Also a configuration of two cascaded FPIs (lambda = 500 nm and lambda = 650 nm) combined with an RGB colour camera is presented. With this tandem configuration, the overall wavelength tuning range of MEMS hyperspectral imagers can be extended to cover a larger range than with a single FPI chip. The potential applications of mobile hyperspectral imagers in the vis-NIR range include authentication, counterfeit detection and potential health/wellness and food sensing applications.

We have developed a microfluidics based sampling system for tissue analytics. The proof-of-concept of the sampling system was demonstrated by extracting lipid samples from tissue biopsies. The sample collection system consists of a disposable silicon based multiport microneedle integrated with polymer microfluidics. The polymethyl methacrylate polymer microfluidic chip has a 10 μl sample reservoir and actuation membranes for liquid pumping. A special automated robotic system was developed to control the positioning of the needle and the sampling procedure on preselected spots on the tissue. Real breast cancer tissue samples were used to test the feasibility of the sampling system. We successfully measured indicative cancer biomarkers from the tissue surface. Phosphatidylcholine and phosphoethanolamine were extracted from the tissue membrane with methyl tert-butyl ether solvent and detected by mass spectrometry. In the future, this tool could be used in characterization of preoperative biopsies and tumour tissues removed during surgery.

Restrictor valves allow proportional control of fluid flow but are rarely integrated in microfluidic systems. In this study, an optically actuated silicon membrane restrictor microvalve is demonstrated. Its actuation is based on the phase transition of paraffin, using a paraffin wax mixed with a suitable concentration of optically absorbing nanographite particles. Backing up the membrane with oil (the melted paraffin) allows for a compliant yet strong contact to the valve seat, which enables handling of high pressures. At flow rates up to 30 mu L min(-1) and at a pressure of 2 bars, the valve can successfully be closed and control the flow level by restriction. The use of this paraffin composite as an adhesive layer sandwiched between the silicon valve and glass eases fabrication. This type of restrictor valve is best suited for high pressure, low volume flow silicon-based nanofluidic systems.

The oil film pressure is one of the key parameters in journal bearings influencing the performance of the bearings. A fibre optic sensor was developed for online determination of actual oil film pressure under load without disturbing the actual tribological contact. Four optical sensors were integrated in a hydrodynamic journal bearing of a Wärtsilä Vasa 4R32 LN E medium-speed diesel engine with four cylinders, maximum power of 1,640 kW and rotating speed on 750 rpm. Online engine tests were carried out with different loads to study the sensor operation in real operating conditions. The engine tests were repeated six times over 4 years of operation reaching up to thousand hours of the engine use. The results showed differences in bearing pressure depending on the position of the sensor and on the operating cycle of the cylinders. The pressure peaks of all four cylinder work cycles could be identified in the measured pressure curves, and the pressure variations within the pressure curves fit well to the diesel engine’s work cycle and mass forces. The sensors had good repeatability over the whole test period.

The oil film pressure is one of the essential functional parameters in journal bearings. Until now, the oil film pressure has been estimated by theoretical calculations, since the measurement of oil film pressure has been a demanding or even unfeasible task in journal bearings, especially in bearings carrying dynamic loads. In this study a new approach has been developed for experimental determination of the oil film pressure.The sensor design utilizes the optical fibre technique and the sensor is integrated in the sliding surface of the bearing thus providing the possibility to measure the actual oil film pressure under load. The finite element method (FEM) calculations have been used for optimizing the design of the sensor and for ensuring the appropriate mechanical performance of the sensor design.The optical sensor was integrated in a hydrodynamic journal bearing made of bronze. A versatile bearing test rig was used for testing the journal bearing with integrated optical sensor. The tests were carried out with both static and dynamic loading. The oil film pressure was measured with different loads and speeds and the data was compared with simulated one. The results showed that the optical sensor was capable to measure the oil film pressure in journal bearing at real operating conditions and the sensitivity of the sensor was good enough to verify the speed and load effects on pressure.According to this work, it is possible to increase the knowledge of true operating conditions of journal bearings by using the optical sensor for oil film pressure measurement. The knowledge can be utilized in the development work of safer and more efficient machines and engines with journal bearings carrying high and dynamic loads. The optical sensor can be used also in other applications for smart control of pressure.

Silicon–glass microchips were designed and fabricated for on-chip solid phase extraction (SPE) and zone electrophoresis studies. The solvent channels for extraction and the separation channels for analyses were fabricated sequentially on the silicon device. Electrical contacts were integrated in a fused silica glass lid. Amorphous silicon thin film electrodes were fabricated for high voltage and conductivity detection. A chip installation rack with electrical and fluidic contacts was constructed to facilitate the experiments. Simulation was used to elucidate both the liquid flow and the electric field distribution. The operational performance of the microchips was demonstrated by using a fluorescein isothiocyanate (FITC)-labelled testosterone derivative as the model analyte and fluorescein as both the negative control and the calibration compounds. In SPE an immunosorbent, based on recombinant anti-testosterone Fab-fragments, was immobilized to activated Sepharose gel. Simultaneous monitoring of the movement of FITC-testosterone from SPE cavity through the channel to the detection point was performed with a laser-induced fluorescence detector. The observed limit of detection for FITC-testosterone was 2 μM.

Several microfluidic platforms incorporating cavities and channels have been designed and fabricated in silicon and fused silica. C4F8 and SF6 plasmas are used to etch reproducibly 400 μm features in silicon and 150 μm in fused silica. Hydrophilic surface characteristics allow capillary action without external pumping or electro-osmosis. Filling of poled cavities can be triggered by increasing temperature i.e. by tuning hydrophobicity of a channel. The pole structure can also be used for sieving particles of different size or elasticity. In this work, agarose beads trapped by poles were used for solid phase extraction. By covering the microfluidic features, filling is also achieved by cooling the substrate. Filling velocities of aqueous solutions have been observed to depend strongly on liquid composition, but also final treatment and roughness of silicon or silica surface. Mixing of two aqueous solutions can also be triggered by increasing temperature. Cavities with pre-immobilised substance can be filled simultaneously or, if necessary, sequentially. Various non-leaking 3D channel networks can be constructed by gluing, fusion or anodic bonding of many silicon or glass wafers including via holes. Integrating of electrical circuits for both silicon and silica is possible by standard IC technology.

Analysis of the β‐blockers oxprenolol, atenolol, timolol, propranolol, metoprolol, and acebutolol in human urine by a combination of isotachophoresis (ITP) and zone electrophoresis (ZE) was investigated. Methods were developed with a conventional capillary electrophoresis (CE) apparatus and a poly(methyl methacrylate) (PMMA) microchip system. With CE the separation of oxprenolol, atenolol, timolol, and acebutolol from a standard solution containing 5 μg/mL of each compound was accomplished by performing ZE with transient ITP. The electrolyte system consisted of 10 m M sodium morpholinoethane sulfonate (pH 5.5) and 0.1% methylhydroxyethylcellulose as the leading electrolyte and 30 m M ortho ‐phosphoric acid (pH 2.0) as both the terminating and the ZE background electrolyte. With the microchip system the separation of oxprenolol and acebutolol from a standard solution containing 10 μg/mL of each compound was accomplished by a coupled‐channel ITP‐ZE device using the same leading electrolyte solution as the CE system but 5 m M glutamic acid (pH 3.4) as terminating and background electrolytes. The systems were used for analyses of patient urine samples. Water‐soluble hydrophilic matrix compounds were removed from the urine samples by solid‐phase extraction (SPE). Limits of quantification below 5 μg/mL could be achieved. The PMMA ITP‐ZE chip has not earlier been used for analyses of any drugs from urine samples.