Acoustofluidic rare cell sample preparation

Acoustofluidics utilizes a combination of acoustics, in the form of ultrasound, and microfluidics to manipulate cells and particles. This has proven to be a versatile method that is gentle to the cells. In this thesis acoustofluidics has been used for processing rare cells in continuous flow. Rare cells are within this thesis defined as cells that are present in numbers of 1-1000 per mL in a much larger population of background cells. Rare cells present in blood have been of particular interest, and cancer cells and bacteria have been used as model cells. In this thesis acoustofluidics has first been used to concentrate cells. This was done by using two-dimensional focusing and a multistage acoustofluidic device where sequential concentration steps, generating moderate concentration factors, could be multiplied into large concentration factors. The usefulness of the method was then extended as the critical particle focusing size was lowered to also allow focusing of bacteria. This was done through using two-dimensional focusing, which was shown to change the acoustic streaming pattern to no longer counteract the primary acoustic radiation force. The new critical particle focusing size was determined to be between 0.5 μm and 0.24 μm in particle diameter for polystyrene-like particles. In the third paper a simplyfied acoustofluidic device, that does not rely on a clean fluid sheath flow to prealign the cells or particles before the separation, was presented. To be able to do this the device used only two-dimensional focusing to prealign the cells. The usefulness of the device was in turn demonstrated with the separation of cancer cells from white blood cells where it was shown to perform comparably to previously presented devices. In the fourth paper a separation method was combined with the concentration method presented in the first paper on an integrated device. The device was shown to be able to simultaneously separate and concentrate cancer cells from white blood cells. Finally, the previously proposed concentration device was integrated with a DEP single cell trapping device further showing the usefulness of the acoustofluidic method. Standing alone, the DEP trapping device could only process sample at a flow rate of 4 μL/min while still maintaining a high trapping efficiency.By integrating the DEP trapping device with the acoustofluidic concentrator device a higher sample inflow rate could be used as the acoustofluidic device could gear down the flow rate before the sample entered the DEP trapping device. Together samples could be processed ~10 times faster than using the DEP trapping device alone, while still recovering over 90% of the cells

Design and technical construction of a tactile display for sensory feedback in a hand prosthesis system

<p>Abstract</p> <p>Background</p> <p>The users of today's commercial prosthetic hands are not given any conscious sensory feedback. To overcome this deficiency in prosthetic hands we have recently proposed a sensory feedback system utilising a "tactile display" on the remaining amputation residual limb acting as man-machine interface. Our system uses the recorded pressure in a hand prosthesis and feeds back this pressure onto the forearm skin. Here we describe the design and technical solution of the sensory feedback system aimed at hand prostheses for trans-radial/humeral amputees. Critical parameters for the sensory feedback system were investigated.</p> <p>Methods</p> <p>A sensory feedback system consisting of five actuators, control electronics and a test application running on a computer has been designed and built. Firstly, we investigate which force levels were applied to the forearm skin of the user while operating the sensory feedback system. Secondly, we study if the proposed system could be used together with a myoelectric control system. The displacement of the skin caused by the sensory feedback system would generate artefacts in the recorded myoelectric signals. Accordingly, EMG recordings were performed and an analysis of the these are included. The sensory feedback system was also preliminarily evaluated in a laboratory setting on two healthy non-amputated test subjects with a computer generating the stimuli, with regards to spatial resolution and force discrimination.</p> <p>Results</p> <p>We showed that the sensory feedback system generated approximately proportional force to the angle of control. The system can be used together with a myoelectric system as the artefacts, generated by the actuators, were easily removed using a simple filter. Furthermore, the application of the system on two test subjects showed that they were able to discriminate tactile sensation with regards to spatial resolution and level of force.</p> <p>Conclusions</p> <p>The results of these initial experiments in non-amputees indicate that the proposed tactile display, in its simple form, can be used to relocate tactile input from an artificial hand to the forearm and that the system can coexist with a myoelectric control systems. The proposed system may be a valuable addition to users of myoelectric prosthesis providing conscious sensory feedback during manipulation of objects.</p

Focusing of sub-micrometer particles and bacteria enabled by two-dimensional acoustophoresis.

Handling of sub-micrometer bioparticles such as bacteria are becoming increasingly important in the biomedical field and in environmental and food analysis. As a result, there is an increased need for less labor-intensive and time-consuming handling methods. Here, an acoustophoresis-based microfluidic chip that uses ultrasound to focus sub-micrometer particles and bacteria, is presented. The ability to focus sub-micrometer bioparticles in a standing one-dimensional acoustic wave is generally limited by the acoustic-streaming-induced drag force, which becomes increasingly significant the smaller the particles are. By using two-dimensional acoustic focusing, i.e. focusing of the sub-micrometer particles both horizontally and vertically in the cross section of a microchannel, the acoustic streaming velocity field can be altered to allow focusing. Here, the focusability of E. coli and polystyrene particles as small as 0.5 μm in diameter in microchannels of square or rectangular cross sections, is demonstrated. Numerical analysis was used to determine generic transverse particle trajectories in the channels, which revealed spiral-shaped trajectories of the sub-micrometer particles towards the center of the microchannel; this was also confirmed by experimental observations. The ability to focus and enrich bacteria and other sub-micrometer bioparticles using acoustophoresis opens the research field to new microbiological applications

Secret-keeping in therapy by clients who are sexually attracted to children

Objective This study investigated the reasons why pedohebephilic clients disclose their sexual attraction to children in therapy and the experiences associated with this decision among English-speaking samples. Method: The pre-registered online survey combined (1) quantitative correlational data of self-reported improvement, alliance, therapist reaction to disclosure, and the belief that mandatory reporting laws were in place, and (2) qualitative data about reasons for disclosure or no disclosure as well as perceived consequences. The sample consisted of pedohebephilic people who have been clients in therapy and have disclosed (n = 96) or not disclosed (n = 40). Results: While the disclosure and no disclosure groups did not differ in improvement or beliefs about mandatory reporting, those who had disclosed reported a stronger alliance. Clients who did not perceive the therapist’s reaction as supportive reported less improvement than the no disclosure group. Thematic analysis of qualitative data identified three themes concerning motives for disclosing or not disclosing and a fourth regarding differential impacts of disclosure. Discussion: This study indicates that disclosing pedohebephilia does not in and of itself lead to improvement but is contingent on a therapist’s reaction

Label-free single-cell separation and imaging of cancer cells using an integrated microfluidic system

The incidence of cancer is increasing worldwide and metastatic disease, through the spread of circulating tumor cells (CTCs), is responsible for the majority of the cancer deaths. Accurate monitoring of CTC levels in blood provides clinical information supporting therapeutic decision making, and improved methods for CTC enumeration are asked for. Microfluidics has been extensively used for this purpose but most methods require several post-separation processing steps including concentration of the sample before analysis. This induces a high risk of sample loss of the collected rare cells. Here, an integrated system is presented that efficiently eliminates this risk by integrating label-free separation with single cell arraying of the target cell population, enabling direct on-chip tumor cell identification and enumeration. Prostate cancer cells (DU145) spiked into a sample with whole blood concentration of the peripheral blood mononuclear cell (PBMC) fraction were efficiently separated and trapped at a recovery of 76.2 ± 5.9% of the cancer cells and a minute contamination of 0.12 ± 0.04% PBMCs while simultaneously enabling a 20x volumetric concentration. This constitutes a first step towards a fully integrated system for rapid label-free separation and on-chip phenotypic characterization of circulating tumor cells from peripheral venous blood in clinical practice

How old was she? The accuracy of assessing the age of adolescents' based on photos

Information on the degree to which individuals can make accurate estimations of someone's age can be of importance in different legal contexts, such as for example child sexual abuse cases in which the victim is an adolescent and asylum procedures. There is, however, a scarcity of studies concerning age estimations conducted with young target persons. Using facial photos of target persons aged 12-18 years, we investigated the effects of gender, age, and ethnicity of both targets (n = 240) and observers (n = 869) on the accuracy of age estimation. We also investigated the effects of targets' facial expressions (neutral or smiling), use of makeup, and photo quality. Participants overestimated the age of the adolescents by, on average, 3.51 years. Participants overestimated the age of young adolescent girls to a greater extent than that of younger boys. Men made larger overestimations than women. Participants also estimated smiling targets as being older than targets with neutral facial expression, and the age of girls with makeup to be older than girls without makeup. Because there was considerable variation in the accuracy of estimations, and overestimates were common, we conclude that the ability of individuals to estimate the age of adolescents is generally low. This might have important legal implications.Peer reviewe

Vector Autoregressive Hierarchical Hidden Markov Models for Extracting Finger Movements Using Multichannel Surface EMG Signals

We present a novel computational technique intended for the robust and adaptable control of a multifunctional prosthetic hand using multichannel surface electromyography. The initial processing of the input data was oriented towards extracting relevant time domain features of the EMG signal. Following the feature calculation, a piecewise modeling of the multidimensional EMG feature dynamics using vector autoregressive models was performed. The next step included the implementation of hierarchical hidden semi-Markov models to capture transitions between piecewise segments of movements and between different movements. Lastly, inversion of the model using an approximate Bayesian inference scheme served as the classifier. The effectiveness of the novel algorithms was assessed versus methods commonly used for real-time classification of EMGs in a prosthesis control application. The obtained results show that using hidden semi-Markov models as the top layer, instead of the hidden Markov models, ranks top in all the relevant metrics among the tested combinations. The choice of the presented methodology for the control of prosthetic hand is also supported by the equal or lower computational complexity required, compared to other algorithms, which enables the implementation on low-power microcontrollers, and the ability to adapt to user preferences of executing individual movements during activities of daily living

Automatic hand phantom map generation and detection using decomposition support vector machines

Background: There is a need for providing sensory feedback for myoelectric prosthesis users. Providing tactile feedback can improve object manipulation abilities, enhance the perceptual embodiment of myoelectric prostheses and help reduce phantom limb pain. Many amputees have referred sensation from their missing hand on their residual limbs (phantom maps). This skin area can serve as a target for providing amputees with non-invasive tactile sensory feedback. One of the challenges of providing sensory feedback on the phantom map is to define the accurate boundary of each phantom digit because the phantom map distribution varies from person to person. Methods: In this paper, automatic phantom map detection methods based on four decomposition support vector machine algorithms and three sampling methods are proposed, complemented by fuzzy logic and active learning strategies. The algorithms and methods are tested on two databases: the first one includes 400 generated phantom maps, whereby the phantom map generation algorithm was based on our observation of the phantom maps to ensure smooth phantom digit edges, variety, and representativeness. The second database includes five reported phantom map images and transformations thereof. The accuracy and training/ classification time of each algorithm using a dense stimulation array (with 100 $$\times$$ × 100 actuators) and two coarse stimulation arrays (with 3 $$\times$$ × 5 and 4 $$\times$$ × 6 actuators) are presented and compared. Results: Both generated and reported phantom map images share the same trends. Majority-pooling sampling effectively increases the training size, albeit introducing some noise, and thus produces the smallest error rates among the three proposed sampling methods. For different decomposition architectures, one-vs-one reduces unclassified regions and in general has higher classification accuracy than the other architectures. By introducing fuzzy logic to bias the penalty parameter, the influence of pooling-induced noise is reduced. Moreover, active learning with different strategies was also tested and shown to improve the accuracy by introducing more representative training samples. Overall, dense arrays employing one-vs-one fuzzy support vector machines with majority-pooling sampling have the smallest average absolute error rate (8.78% for generated phantom maps and 11.5% for reported and transformed phantom map images). The detection accuracy of coarse arrays was found to be significantly lower than for dense array. Conclusions: The results demonstrate the effectiveness of support vector machines using a dense array in detecting refined phantom map shapes, whereas coarse arrays are unsuitable for this task. We therefore propose a two-step approach, using first a non-wearable dense array to detect an accurate phantom map shape, then to apply a wearable coarse stimulation array customized according to the detection results. The proposed methodology can be used as a tool for helping haptic feedback designers and for tracking the evolvement of phantom maps