Showing papers in "Expert Review of Medical Devices in 2011"

Design properties of hydrogel tissue-engineering scaffolds

Abstract: This article summarizes the recent progress in the design and synthesis of hydrogels as tissue-engineering scaffolds. Hydrogels are attractive scaffolding materials owing to their highly swollen network structure, ability to encapsulate cells and bioactive molecules, and efficient mass transfer. Various polymers, including natural, synthetic and natural/synthetic hybrid polymers, have been used to make hydrogels via chemical or physical crosslinking. Recently, bioactive synthetic hydrogels have emerged as promising scaffolds because they can provide molecularly tailored biofunctions and adjustable mechanical properties, as well as an extracellular matrix-like microenvironment for cell growth and tissue formation. This article addresses various strategies that have been explored to design synthetic hydrogels with extracellular matrix-mimetic bioactive properties, such as cell adhesion, proteolytic degradation and growth factor-binding.

Wireless communication with implanted medical devices using the conductive properties of the body

Abstract: Many medical devices that are implanted in the body use wires or wireless radiofrequency telemetry to communicate with circuitry outside the body. However, the wires are a common source of surgical complications, including breakage, infection and electrical noise. In addition, radiofrequency telemetry requires large amounts of power and results in low-efficiency transmission through biological tissue. As an alternative, the conductive properties of the body can be used to enable wireless communication with implanted devices. In this article, several methods of intrabody communication are described and compared. In addition to reducing the complications that occur with current implantable medical devices, intrabody communication can enable novel types of miniature devices for research and clinical applications.

The effects of repetitive transcranial magnetic stimulation in the treatment of depression.

Abstract: Repetitive transcranial magnetic stimulation (rTMS) is currently emerging as one of the first fundamentally new treatments in psychiatric practice for a considerable number of years. Research into the use of rTMS for the treatment of patients with depression has now been conducted for over 15 years. The aim of this article was to review the development of rTMS treatment for depression and the current state of evidence supporting its use. The vast majority of the trials conducted on the technique have evaluated the efficacy of high-frequency rTMS applied to the left dorsolateral prefrontal cortex using a set of parameters very similar to those originally described in the mid-1990s. This 'standard' form of rTMS clearly appears to have antidepressant efficacy, and its effects have now been confirmed in several large-scale clinical trials and a number of meta-analyses: response is better than that of sham stimulation, although the number of responders to treatment is relatively modest. A wide range of alternative forms of rTMS have been, or are currently being, evaluated. Low-frequency stimulation applied to the right prefrontal cortex appears to have similar efficacy to standard treatment and it is possible that the bilateral approaches may prove more effective. Novel methods of stimulation, such as priming stimulation, theta-burst stimulation and deep TMS, appear to be promising although require further evaluation. Significant benefit appears likely to accumulate through the use of methods that involve a more reliable targeting of prefrontal brain regions. Research is also required to evaluate the long-term effects of rTMS treatment, its use as a maintenance therapy and to establish reliable predictors of response to treatment.

Left ventricular assist device-related infections: past, present and future.

Abstract: Over the last decade, left ventricular assist device (LVAD) implantation has emerged as an alternative treatment strategy in patients with advanced heart failure irrespective of their transplant eligibility. However, success and applicability of this therapy is largely limited by high complication rates associated with these devices. Although superior outcomes have been achieved with the second-generation continuous-flow LVADs, device-related infections continue to be a prevalent complication in this patient population and contribute significantly to the financial burden of this therapy due to an increased need for hospitalizations and surgical interventions. Patient selection, device design and LVAD-induced immune system dysfunction appear to be major risk factors for the development of device-related infections. Improvements in device design and better patient selection strategies, particularly with respect to identifying individuals with genetic susceptibility to device-related infections, may further reduce this prevalent complication and improve outcomes in patients with advanced heart failure.

In vivo nucleic acid delivery with PEI and its derivatives: current status and perspectives

Abstract: Poly(ethylenimine) (PEI) has recently emerged as a favorable candidate for nucleic acid (NA) delivery because of its good effectivity at low cost. Despite copious derivatives and formulations being explored over the years, there is a scarcity of efforts to systematically review the current status and unmet needs of related research. The objective of this article is to fill this gap by revisiting the recent advances and challenges in in vivo NA delivery mediated by PEI. For this, related literature was retrieved from PubMed and Web of Science, and among the 530 articles yielded, 49 recent in vivo studies were selected for further analysis. Based on the distillation of literature, implications for research will be drawn and prospects of PEI-mediated NA delivery for stem cell- and RNA-based therapies will be explored. It is hoped that this article could add a new insight to the field and to clinical endeavors in the future.

Microneedle arrays as medical devices for enhanced transdermal drug delivery

Abstract: In order to exploit the transdermal route for systemic delivery of a wide range of drug molecules, including peptide/protein molecules and genetic material, a means of disrupting the excellent barrier properties of the uppermost layer of the skin, the stratum corneum, must be sought. The use of microneedle (MN) arrays has been proposed as a method to temporarily disrupt the barrier function of the skin and thus enable enhanced transdermal drug delivery. MN arrays consist of a plurality of micron-sized needles, generally ranging from 25 to 2000 µm in height, of a variety of different shapes and composition (e.g., silicon, metal, sugars and biodegradable polymers). The application of such MN arrays to the skin results in the creation of aqueous channels that are orders of magnitude larger than molecular dimensions and, therefore, should readily permit the transport of macromolecules. This article will focus on recent and future developments for MN technology, focusing on the materials used for MN fabrication, the forces required for MN insertion and potential safety aspects that may be involved with the use of MN devices.

Military applications of novel hemostatic devices.

Abstract: Hemorrhage remains the leading cause of death in combat and the primary cause of preventable death after civilian trauma. Over the last 10 years, major improvements in hemostatic agents have resulted in new dressings that are replacing gauze as the standard of care for compressible hemorrhage. This has inspired a plethora of hemostatic products, some of which have been used in the combat and civilian sector. These dressings are crucial in their ability to control initial hemorrhage so that transfer to a higher level of care can occur, thereby potentially improving survival. Current research is ongoing to determine which of the available hemostatic agents is the most efficacious. The current recommendation by the Committee on Tactical Combat Casualty Care is that Combat Gauze™ (Z-Medica) is the hemostatic dressing of choice and every soldier carries this dressing in their first aid kit. This article reviews novel hemostatic agents used by first responders in the military and civilian sectors.

Polyurethane heart valves: past, present and future

Abstract: Replacement cardiac valves have been in use since the 1950s, and today represent the most widely used cardiovascular devices. One type of replacement cardiac valve, the polyurethane heart valve, has been around since the first stages of prosthesis development, and has made advances along with the development of biological and mechanical heart valves over the past 60 years. During this time, problems with durability and biocompatibility have held back polyurethane valves, but progress in materials and manufacturing techniques can lead the way to a brighter future for these devices and their huge potential. This article describes previous efforts to manufacture polyurethane heart valves, highlights the challenges of manufacturing and explains the factors influencing durability and successful functioning of such a device.

Laser systems for ablative fractional resurfacing.

Abstract: Ablative fractional resurfacing (AFR) creates microscopic vertical ablated channels that are surrounded by a thin layer of coagulated tissue, constituting the microscopic treatment zones (MTZs). AFR induces epidermal and dermal remodeling, which raises new possibilities for the treatment of a variety of skin conditions, primarily chronically photodamaged skin, but also acne and burn scars. In addition, it is anticipated that AFR can be utilized in the laser-assisted delivery of topical drugs. Clinical efficacy coupled with minimal downtime has driven the development of various fractional ablative laser systems. Fractionated CO(2) (10,600-nm), erbium yttrium aluminum garnet, 2940-nm and yttrium scandium gallium garnet, 2790-nm lasers are available. In this article, we present an overview of AFR technology, devices and histopathology, and we summarize the current clinical possibilities with AFR incorporating our personal experience. AFR is still in the exploratory era, and systematic investigations of clinical outcomes related to various system settings are needed.

Functionalized carbon nanotubes for anticancer drug delivery

Abstract: In vitro and in vivo results reflect that functionalized carbon nanotubes (f-CNTs) are promising for the development of unique delivery systems of anticancer drugs. Functionalization of CNTs and drug loading are realized by covalent attachment and/or physical approaches. Poly(ethylene glycol) is the most adopted species for functionalization, which can increase the dispersity in aqueous solution and biocompatibility of CNTs. Several types of anticancer drugs, such as paclitaxel and doxorubicin, are loaded onto f-CNTs and their treatment efficacy has been demonstrated in vitro and in vivo. However, f-CNTs of well-controlled structures, such as uniform length and well-defined chemistry, which are not available so far, are important to solve the current controversy over the mechanisms of cell uptake of f-CNTs, and are a prerequisite to investigate whether f-CNTs can be platform materials for anticancer drug delivery with improved efficacy.

New-generation diabetes management: glucose sensor-augmented insulin pump therapy

Abstract: Diabetes is one of the most common chronic disorders with an increasing incidence worldwide. Technologic advances in the field of diabetes have provided new tools for clinicians to manage this challenging disease. For example, the development of continuous subcutaneous insulin infusion systems have allowed for refinement in the delivery of insulin, while continuous glucose monitors provide patients and clinicians with a better understanding of the minute to minute glucose variability, leading to the titration of insulin delivery based on this variability when applicable. Merging of these devices has resulted in sensor-augmented insulin pump therapy, which became a major building block upon which the artificial pancreas (closed-loop systems) can be developed. This article summarizes the evolution of sensor-augmented insulin pump therapy until present day and its future applications in new-generation diabetes management.

Stent placement for esophageal strictures: an update.

Abstract: The use of stents for esophageal strictures has evolved rapidly over the past 10 years, from rigid plastic tubes to flexible self-expanding metal (SEMS), plastic (SEPS) and biodegradable stents. For the palliative treatment of malignant dysphagia both SEMS and SEPS effectively provide a rapid relief of dysphagia. SEMS are preferred over SEPS, as randomized controlled trials have shown more technical difficulties and late migration with plastic stents. Despite specific characteristics of recently developed stents, recurrent dysphagia due to food impaction, tumoral and nontumoral tissue overgrowth, or stent migration, remain a major challenge. The efficacy of stents with an antireflux valve for patients with distal esophageal cancer varies between different stent designs. Concurrent treatment with chemotherapy and/or radiotherapy seems to be safe and effective. In the future, it can be expected that removable stents will be used as a bridge to surgery to maintain luminal patency during neoadjuvant treatment. For benign strictures, new stent designs, such as fully covered SEMS and biodegradable stents, may potentially reduce complications during stent removal.

Myoelectric training systems.

Abstract: Myoelectric prostheses aim to restore the functionality of amputated limbs and improve the quality of life of amputees. Myoelectric training systems are used to train and assess the ability of amputees in how to use myoelectric technology in advance of receiving their actual myoelectric prostheses. This article describes the myoelectric training systems that have been developed over the last 20 years in both the literature and commercial industries. The results of this article will identify common features in the training systems and suggest areas for future improvement.

HeartMate® II continuous-flow left ventricular assist system.

Abstract: Left ventricular assist devices (LVADs) have emerged as a beneficial therapeutic strategy proven to improve the morbidity and mortality of patients with advanced heart failure Continuous-flow rotary LVADs have been developed in the hopes of delivering circulatory support in a more durable manner with fewer device-related complications The HeartMate(®) II continuous-flow left ventricular assist system (LVAS; Thoratec Corporation, Pleasanton, CA, USA) has become the standard of care for heart failure patients who require long-term mechanical circulatory support The efficacy of the HeartMate II has been demonstrated in patients where temporary support with an LVAD is needed until a suitable donor organ can be found for transplant (termed 'bridge to transplantation'), as well as for terminally-ill heart failure patients who are not candidates for transplant ('destination therapy') When directly compared with a pulsatile LVAD, the implantation of a HeartMate II LVAS resulted in an overall improvement in survival with a reduction in the number of device-related complications and adverse events The purpose of this article is threefold: to describe the history of the development of continuous-flow LVADs; to describe the technology of the HeartMate II; and, finally, to review the clinical outcomes in patients who have been implanted with the device

From lead management to implanted patient management: indications to lead extraction in pacemaker and cardioverter-defibrillator systems.

Abstract: Based on the published results primarily from cohort studies, percutaneous lead extraction is now considered a safe procedure and indications for its use have broadened from device-related infections to less strict indications, such as recurrent isolated bacteremia, asymptomatic upper vein occlusion and malfunctioning/redundant leads. Almost 50% of electrophysiologists consider lead extraction in these latter situations. To broaden its implementation, further prospective evaluation against conservative approaches is still needed. Rather than only aiming at short-term results, this technique should be integrated into wide-ranging tailored long-term strategies to manage all of the different issues of implanted patients.

Renaissance of contact x-ray therapy for treating rectal cancer.

Abstract: †Contact x-ray therapy (CXRT) with 50 kV has proven to be an efficient radiation therapy technique to achieve local control and rectal preservation for early rectal adenocarcinoma. Despite these results, CXRT has not been used due to the shortage of the no longer manufactured Philips RT 50™ unit. Recently, a new CXRT machine (Papillon 50™) became available on the market. This machine delivers a beam of 50 kV with a dose rate close to 15 Gy/min and has a percentage depth dose of 50% at 6–7 mm. The applicator size varies from 2–3 cm in diameter. Due to the original design of the main tube, treatment delivery is quick and more comfortable for the patients. An online viewing system incorporated in the tube allows a good visualization of the tumor with improved accuracy of radiation delivery. An international collaborative trial (Contact Endoscopic Microsurgery [CONTEM]) was set up to accrue approximately 300 cases of rectal adenocarcinoma staged T1, T2 or early T3 tumors in the UK, France, Denmark and Sweden. This trial should confirm the role of CXRT in curative treatment with organ preservation for early rectal cancers.

State of the art in hard-on-hard bearings: how did we get here and what have we achieved?

Abstract: Total hip arthroplasty has shown excellent results in decreasing pain and improving function in patients with degenerative disease of the hip. Improvements in prosthetic materials, designs and implant fixation have now resulted in wear of the bearing surface being the limitation of this technology, and a number of hard-on-hard couples have been introduced to address this concern. The purpose of this article is to review the origins, development, survival rates and potential advantages and disadvantages of the following hard-on-hard bearings for total hip arthroplasty: metal-on-metal standard total hip arthroplasty; metal-on-metal hip resurfacing arthroplasty, ceramic-on-ceramic total hip arthroplasty; and ceramic-on-metal bearings. Improvements in the manufacturing of metal-on-metal bearings over the past 50 years have resulted in implants that provide low wear rates and allow for the use of large femoral heads. However, concerns remain regarding elevated serum metal ion levels, potential teratogenic effects and potentially devastating adverse local tissue reactions, whose incidence and pathogenesis remains unclear. Modern total hip resurfacing has shown excellent outcomes over 10 years in the hands of experienced surgeons. Current ceramic-on-ceramic bearings have demonstrated excellent survival with exceptionally low wear rates and virtually no local adverse effects. Concerns remain for insertional chipping, in vivo fracture and the variable incidence of squeaking. Contemporary ceramic-on-metal interfaces are in the early stages of clinical use, with little data reported to date. Hard-on-hard bearings for total hip arthroplasty have improved dramatically over the past 50 years. As bearing designs continue to improve with new and modified materials and improved manufacturing techniques, it is likely that the use of hard-on-hard bearings will continue to increase, especially in young and active patients.

The BridgePoint devices to facilitate recanalization of chronic total coronary occlusions through controlled subintimal reentry.

Abstract: In view of the improved long-term patency with drug-eluting stents, the challenge with chronic total coronary occlusion remains a low primary success rate. Modes of failure to open a chronic total coronary occlusion are mainly related to the inability to pass a wire through the proximal occlusion cap, and the most difficult part of the procedure is to guide the wire into the distal true lumen. A frequent situation is a subintimal wire position. The BridgePoint (BridgePoint Medical, MN, USA) family of devices is designed to cope with both of these problems. First, the CrossBoss™ catheter aims at passing through the proximal cap by manual rotation of a blunt proximal tip, and second, in case of a subintimal position, the Stingray™ balloon enables guided reentry from the subintimal space into the true lumen. Certain features of an occlusion might favor the CrossBoss device, while the reentry approach may also be used as a standalone bailout method. The aim is to provide a means to resolve otherwise failed attempts and to make it unnecessary to resort to the more complex and time-consuming retrograde wire techniques through collateral channels with the associated potential higher procedural risks.

Assessment of a novel lung sealant for performing endoscopic volume reduction therapy in patients with advanced emphysema

Abstract: AeriSeal® Emphysematous Lung Sealant is a novel endoscopic lung-volume reduction therapy designed to reduce hyperinflation and improve pulmonary function and quality of life in patients with advanced emphysema. The device is administered to the subsegmental bronchus via a catheter as a 20 ml volume of liquid–foam. It flows into the peripheral airways and alveoli where it polymerizes and functions as a tissue glue, forming a film of material on the lung surface that seals the target region to cause durable absorption atelectasis. The AeriSeal System received CE mark approval for the treatment of patients with advanced upper lobe predominant and homogeneous emphysema based upon favorable results from clinical studies, and is commercially available in Europe. Patient and treatment site selection algorithms have been developed to simplify product use and optimize outcomes. This manuscript summarizes how the device is used, its mechanism of action and clinical trial results supporting its safety and efficacy.

Cochlear implants: current status and future potential

Abstract: This article reviews the current status of cochlear implantation in both adults and children, including expanding candidacy groups, bilateral implantation, advances in speech processing software, internal and external device hardware, surgical techniques and outcomes. Promising advances, novel therapies and evolving concepts are also highlighted in terms of their future impact on clinical outcomes.

A wearable artificial kidney: technical requirements and potential solutions.

Abstract: Recently, new approaches for miniaturization and transportability of medical devices have been developed, paving the way for wearability and the possibility of implantation, for renal replacement therapies. A wearable artificial kidney (WAK) is a medical device that supports renal function during ambulation or social activities out of hospital. With the aim of improving dialysis patients’ quality of life, WAK systems have been developed for several decades. However, at present there are a lot of technical issues confronting the attempt to apply WAK systems in clinical practice. This article focuses on technical requirements and potential solutions for WAKs and reviews up-to-date approaches related to dialysis membrane, dialysate regeneration, vascular access, patient-monitoring systems and power sources for WAKs.

Measurable evidence of miRNAs as regulators of cancer networks and therapeutic targets

Abstract: miRNAs are small noncoding RNAs (ncRNAs) that contribute to gene expression regulation. In diseases such as cancer, deregulated miRNA expression can be measured by high-throughput technology. Restoring perturbed miRNA expression may result in novel therapeutic developments that, when added to current standard treatment, could improve the outcomes of patients with cancer. The advantage of using miRNA approaches is based on their ability to target multiple genes concurrently, resulting in homeostasis of deregulated signaling pathway networks. However, this impact on expression profiling of multiple genes simultaneously, several of which may regulate normal function of noncancer cells, can lead to substantial adverse effects. Apart from miRNAs, transcription factors, epigenetic changes and chromatin contribute to gene regulation in a complex functional regulatory network. Here I discuss the latest advances in translating miRNA research into the improved management of cancer, and how challenges might be overcome.

Arthroscopic rotator cuff repair: suture anchor properties, modes of failure and technical considerations

Abstract: Rotator cuff injury and tears are a common source of shoulder pain, particularly among the elderly. Arthroscopic repair has now become the mainstay in the treatment of significant injuries that have failed conservative therapy. Compared with the traditional open technique, arthroscopic repair offers patients smaller incisions and less soft-tissue trauma, which result in improved postoperative pain and rehabilitation. The advances that have made arthroscopic repairs a reality includes improvement in arthroscopic rotator cuff instrumentation, particularly suture anchors. Suture anchors are used to reattach the torn rotator cuff tissue back onto the bone. Current rotator cuff anchors vary by design, anchor composition and suture materials. A treating physician should be aware of the advantages and limitations of these implants, which may influence the choice of one anchor over another. In addition to anchor variables, other factors that may affect the success of the repair include the local environment and surgical technique. In this article, various aspects of anchor design will be discussed. In addition, a concise review of technical considerations will also be discussed.

Gamma Knife® radiosurgery for trigeminal neuralgia.

Abstract: Trigeminal neuralgia is characterized by a temporary paroxysmal lancinating facial pain in the trigeminal nerve distribution. The prevalence is four to five per 100,000. Local pressure on nerve fibers from vascular loops results in painful afferent discharge from an injured segment of the fifth cranial nerve. Microvascular decompression addresses the underlying pathophysiology of the disease, making this treatment the gold standard for medically refractory trigeminal neuralgia. In patients who cannot tolerate a surgical procedure, those in whom a vascular etiology cannot be identified, or those unwilling to undergo an open surgery, stereotactic radiosurgery is an appropriate alternative. The majority of patients with typical facial pain will achieve relief following radiosurgical treatment. Long-term follow-up for recurrence as well as for radiation-induced complications is required in all patients undergoing stereotactic radiosurgery for trigeminal neuralgia.

Intervertebral disc properties: challenges for biodevices.

Abstract: Intervertebral disc biodevices that employ motion-preservation strategies (e.g., nucleus replacement, total disc replacement and posterior stabilization devices) are currently in use or in development. However, their long-term performance is unknown and only a small number of randomized controlled trials have been conducted. In this article, we discuss the following biodevices: interbody cages, nuclear pulposus replacements, total disc replacements and posterior dynamic stabilization devices, as well as future biological treatments. These biodevices restore some function to the motion segment; however, contrary to expectations, the risk of adjacent-level degeneration does not appear to have been reduced. The short-term challenge is to replicate the complex biomechanical function of the motion segment (e.g., biphasic, viscoelastic behavior and nonlinearity) to improve the quality of motion and minimize adjacent level problems, while ensuring biodevice longevity for the younger, more active patient. Biological strategies for regeneration and repair of disc tissue are being developed and these offer exciting opportunities (and challenges) for the longer term. Responsible introduction and rigorous assessment of these new technologies are required. In this article, we will describe the properties of the disc, explore biodevices currently in use for the surgical treatment of low back pain (with an emphasis on lumbar total disc replacement) and discuss future directions for biological treatments. Finally, we will assess the challenges ahead for the next generation of biodevices designed to replace the disc.

Quality of life for patients supported on a left ventricular assist device

Abstract: Left ventricular assist devices (LVADs) are mechanical pumps implanted into patients at risk of dying from Stage D heart failure. These devices not only increase survival time, they also significantly improve quality of life. Implantation of a LVAD improves hemodynamics and reduces congestion in both the pulmonary and peripheral vasculature. Improvements in forward blood flow are probably responsible for the significant reduction in the severity of dyspnea and fatigue postimplant. Quality of life is a subjective evaluation and includes aspects of physical, mental and social functioning. Quality of life is significantly improved after implantation of a LVAD, changes little over the duration of support and improves again following heart transplantation. Patients who are discharged home on support report significantly better quality of life than patients who remain in hospital. At home patients can resume physical, mental and social activities that were compromised preimplant. A significant decline in functional ability while on support may be a trigger for patients to initiate discussions regarding LVAD withdrawal. While the bulk of evidence was generated during the era of pulsatile support, preliminary information suggests similar results can be anticipated for patients supported on continuous-flow devices.

Magnetic seizure therapy for treatment-resistant depression.

Abstract: Approximately 30% of people with depression do not respond to standard treatments. Currently, the standard treatment for patients with treatment-resistant depression is electroconvulsive therapy (ECT). ECT, while effective, has a number of common side effects that limit its use - in particular the occurrence of memory impairment. As such, there has been a considerable degree of research effort directed at developing a treatment for treatment-resistant depression that retains the efficacy of ECT but limits the unwanted cognitive side effects. This research has involved modifications to ECT itself, as well as the development of novel brain stimulation methods. Most recently, magnetic seizure therapy (MST) has been developed and trialed with promising results. This article explores the development of MST, as well as providing a discussion of the clinical and practical issues of the use of MST for the treatment of depression.

Seeking the 'holy Braille' display: might electromechanically active polymers be the solution?

Abstract: For over 50 years, there have been many attempts to develop paperless Braille displays that would provide readers with visual impairments access to digital information. Such devices are conceived as electronically refreshable tactile displays allowing users to read dynamically presented Braille text. The displays are designed as arrays of Braille cells, corresponding to the individual characters of the Braille code. The emerging world standard for refreshable Braille displays utilizes eight dots, arranged in two columns of four dots each. The height of each dot with respect to the reading surface must be individually controllable, so as to produce two states: dot raised and dot lowered. This allows for representing 256 different combinations – that is, 256 different Braille characters. The complexity of developing such tactile interfaces deals with the need for suitable actuation technologies able to drive each single dot of each single cell of the whole display, while minimizing size, weight, cost and energy consumption (especially for portable devices). To this end, electromagnets, bimetals, shape memory alloys, pneumatic drives, piezo ceramic reeds and many other actuation technologies have been extensively investigated, but, at best, efforts have only resulted in complicated and expensive display devices. Most commercially available refreshable Braille displays have a single line of 20–80 Braille characters (cells) and cost several thousand US dollars. The original equipment manufacturer cost of commercially produced piezoelectric Braille cells is approximately US$35 per cell, or US$4.38 per Braille dot. Nearly all Braille modules available today use piezoelectric ceramic bimorph reeds to actuate the Braille dots. The piezo reeds are mounted as a stairstepped stack of cantilevers, each with a Braille pin resting on its free end. Each reed can lift the dome top of its 1.5 mm diameter Braille pin approximately 0.5 mm above the reading surface. As shown in Figure 1, a typical module has four layers of side-by-side pairs of reeds mounted horizontally, below and parallel to the top reading surface. Figure 1 also shows the associated data latch and 200-V driver circuitry required for, and integrated into, each Braille cell module. These Braille cell modules are horizontally mounted next to each other, forming an arbitrarily long single line of cells (typically 20, 40 or 80 cells). It is possible to mount a maximum of two of these lines together, nose-to-nose, obtaining a two-line display, although packaging size and cost limit most displays to a single line. Therefore, owing to the encumbrance of the long cantilevers (Figure 1), modern refreshable Braille displays are limited to only a single reading line, or Expert Rev. Med. Devices 8(5), 529–532 (2011)

Nanomedicine's promising therapy: magnetic drug targeting.

Abstract: Magnetic drug targeting is a promising therapy that can benefit patients, as well as provide novel opportunities for pharmaceutical and medical technology/device industries.

Translating epigenetics into an anticancer drug pipeline for solid tumors.

Abstract: Adapted with permission from [8].The latest genome-wide mapping techniques allow a comprehensive study of transcriptional activity and gene regulation. Epigenetic marks, such as DNA methylation and...