- Front Matter: Volume 9518
- Tuesday Plenary Session
- Neural and Wireless Interfaces
- Microfluidics and Lab-on-a-Chip I
- Biosensors and Medical Sensors I
- Microfluidics and Lab-on-a-Chip II
- Biosensors and Medical Sensors II
- Microfluidics and Lab-on-a-Chip III
- Poster Session
A 16-electrode flexible microprobe presenting an array of holes in its sensing area has been developed using SU-8 negative photoresist as a substrate material. The design of the microprobe consisted on six groups of 2-3 electrodes (50 μm in diameter and separated by 200 μm) placed in-between the array of holes. Distances between each group were appropriated for recording from a ferret slice, allowing us to evaluate the close versus the distant network activity. The holes were designed to allow the flow of oxygenated solution through the probe when measuring the neural activity of cortical slides maintained in vitro, while the gold electrodes have been modified with platinum black to decrease its impedance value and, therefore, improve the measurements.
In particular, with this SU-8 microprobe it has been possible to register spontaneous slow oscillations and also induced activity in all 16 channels. The holes were useful to position puffers that allowed us to locally delivered drugs (glutamate) and to register its response. In addition, they were also used for sticking electrodes to simultaneously record single units that allowed us the synchronous recording of population activity (local field potential) with the electrodes of the probe and single unit activity (with glass or tungsten electrodes), demonstrating the feasibility of using SU-8 for the fabrication of neural microprobes as it can be customized to the required design.
The artificial cochlear implant is the only way how to get lost hearing back in some cases. Existing artificial cochlear devices use two separated parts for this purpose: a signal processing unit with transmitter and an implantable receiver with electrodes. This approach is applicable but not fully implantable. A new complex approach to design of a fully implantable artificial cochlea is described in this article.
The proposed artificial cochlea consists of many subcircuits which have to be designed in close context to reach optimal performance and the lowest power consumption. Power consumption should be decreased to a value which allows using cochlear implant as a zero-powered system. A combination of micro-mechanized diaphragm filter bank, possible energy harvesting power source and especially ultra-low power processing electronics is presented in this article. A unique technique for nerve stimulatory output signal generation is discussed. This new technique named charge push-through electronics should use the major part of energy generated by energy harvesting subcircuit for output useful signal generation with minimal undesirable current.
Mechanical parts of the subcircuits were simulated as complex electro-mechanical simulation models in ANSYS, CoventorWare, Matlab and SPICE environment. First, the real energy harvesting power source (human motion and temperature) behavior was measured. The model of this behavior was created in simulation environment and then the whole electronics simulation model for energy harvesting circuits was estimated. Next, signal processing circuits powered from energy harvesting power source were designed and simulated. The new signal processing circuits were simulated in relation to the results of complex electro mechanical diaphragm and SPICE energy harvesting power source simulation.
The future of research in biology and medicine depends on modular tridimensional cell culture platforms with suitable on-demand geometries that can imitate any cell-specific environment with micron-size features. A high level of control of physico-chemical properties of the substrates is critical, as mechanotransduction signals are passed to the cells that sense their environment. The possibility to pattern nanoscale geometries on chip are also leading to better culture results. All these biomimicry parameters influence the cells phenotype, structure and behavior and are now opening new perspectives in 3D cell culturing for basic biology, medicine and drug testing applications. However, this growing need for on-demand 3D platforms is currently limited by two factors: the specificity of the commercial biochips is not suitable for many cell types and the high cost of technology used to design and fabricate custom-made substrates.
In this work, we present the application of a simple, low-cost alternative technique enabling the rapid fabrication of on-demand, custom-made biochips for cell culture with micron-scale resolution. We developed a process that enables the use of low-power, low-cost lasers to etch on-demand micropatterns in transparent biopolymers, circumventing the need for high power lasers or photolithography. We also report the integration of embedded electronics for in situ monitoring or actuation and microchannels on chip. We also succeeded in producing localized carbon nanodomains that are enhancing cell cultures and allowing regionalization in 3D cell culture platforms.
Traditional marine ecotoxicity testing is inherently labor intensive, requiring extensive manual procedures both to set up the tests and more importantly to collect experimental readouts. Moreover, static test procedures offer poor control of water parameters such as toxicant concentration and dissolved oxygen, which are important considerations in evaluating environmental impacts of aquatic pollution. So far only minimal levels of automation have been adopted in ecotoxicology. Our current work attempts to address the current limitations by capitalizing on latest advances in microfluidics, 3D printing and laser micromachining technologies to develop highly customized, low cost and high-throughput devices.
Here we for the first time introduce a proof-of-concept laboratory automation system to perform ecotoxicity tests on the marine amphipod Allorchestes compressa in a microfluidic environment. Our innovative system incorporated a microperfusion Lab-on-a-Chip device that enabled the biotests to be run in both closed- or open-loop regimens. Miniaturized video cameras were utilized to monitor the amphipods movement patterns during the experiments. Furthermore innovative video analysis algorithms was applied for detection of sub-lethal endpoints such as changes in swimming activity that would otherwise go unnoticed. A key advantage of this flow-through system as compared to conventional approach is the automation of analysis and emphasis on sub-lethal behavioral parameters.
We present preliminary data validating the technology and compared to a gold standard method for testing organisms from the order Amphipoda This work provides a foundation to enable automation of ecotoxicity biotests performed on marine test organisms.
Non-invasive and real-time visualisation of metabolic activities in living small organisms such as zebrafish embryo and larvae has not yet been attempted due to profound analytical limitations of existing technologies. Significant progress in the development of physico-optical oxygen sensors using luminescence quenching by molecular oxygen has recently been made. Sensing using such microsensors is, however, still performed in small glass chambers that hold single specimens and thus not amenable for high-throughput data acquisition.
In this work, we present a proof-of-concept approach by using microfluidic Lab-on-a-Chip (LOC) technologies combined with sophisticated optoelectronic sensors. The LOC device is capable of immobilising live zebrafish embryos with continuous flow perfusion, while the sensor uses innovative Fluorescence Ratiometric Imaging (FRIM) technology that can kinetically quantify the temporal patterns of aqueous oxygen gradients at a very fine scale based on signals coming from an optical sensor referred to as a sensor foil. By embedding the sensor foil onto the microfluidic living embryo array system, we demonstrated in situ FRIM on developing zebrafish embryos. Future integration of microfluidic chip-based technologies with FRIM technology represents a noteworthy direction to miniaturise and revolutionise research on metabolism and physiology in vivo.