Hybrid triboelectric-piezoelectric nanogenerator for long-term load monitoring in total knee replacements

A self-powered and durable pressure sensor for large-scale pressure detection on the knee implant would be highly advantageous for designing long-lasting and reliable knee implants as well as obtaining information about knee function after the operation. The purpose of this study is to develop a robust energy harvester that can convert wide ranges of pressure to electricity to power a load sensor inside the knee implant. To efficiently convert loads to electricity, we design a cuboid-array-structured tribo-pizoelectric nanogenerator (TPENG) in vertical contact mode inside a knee implant package. The proposed TPENG is fabricated with aluminum and cuboid-patterned silicone rubber layers. Using the cuboid-patterned silicone rubber as a dielectric and aluminum as electrodes improves performance compared with previously reported self-powered sensors. The combination of 10w t % dopamine-modified BaTiO3 piezoelectric nanoparticles in the silicone rubber enhanced electrical stability and mechanical durability of the silicone rubber. To examine the output, the package-harvester assemblies are loaded into an MTS machine under different periodic loading. Under different cyclic loading, frequencies, and resistance loads, the harvester's output performance is also theoretically studied and experimentally verified. The proposed cuboid-array-structured TPENG integrated into the knee implant package can generate approximately 15μ W of apparent power under dynamic compressive loading of 2200 N magnitude. In addition, as a result of the TPENG's materials being effectively optimized, it possesses remarkable mechanical durability and signal stability, functioning after more than 30 000 cycles under 2200 N load and producing about 300 V peak to peak. We have also presented a mathematical model and numerical results that closely capture experimental results. We have reported how the TPENG charge density varies with force. This study represents a significant advancement in a better understanding of harvesting mechanical energy for instrumented knee implants to detect a load imbalance or abnormal gait patterns.

Covert Channel Communication as an Emerging Security Threat in 2.5D/3D Integrated Systems

In this paper, first, a broad overview of existing covert channel communication-based security attacks is provided. Such covert channels establish a communication link between two entities that are not authorized to share data. The secret data is encoded into different forms of signals, such as delay, temperature, or hard drive location. These signals and information are then decoded by the receiver to retrieve the secret data, thereby mitigating some of the existing security measures. The important steps of covert channel attacks are described, such as data encoding, communication protocol, data decoding, and models to estimate communication bandwidth and bit error rate. Countermeasures against covert channels and existing covert channel detection techniques are also summarized. In the second part of the paper, the implications of such attacks for emerging packaging technologies, such as 2.5D/3D integration are discussed. Several covert channel threat models for 2.5D/3D ICs are also proposed.

Self-Powered Load Sensing Circuitry for Total Knee Replacement

There has been a significant increase in the number of total knee replacement (TKR) surgeries over the past few years, particularly among active young and elderly people suffering from knee pain. Continuous and optimal monitoring of the load on the knee is highly desirable for designing more reliable knee implants. This paper focuses on designing a smart knee implant consisting of a triboelectric energy harvester and a frontend electronic system to process the harvested signal for monitoring the knee load. The harvester produces an AC signal with peak voltages ranging from 10 V to 150 V at different values of knee cyclic loads. This paper demonstrates the measurement results of a PCB prototype of the frontend electronic system fabricated to verify the functionality and feasibility of the proposed approach for a small range of cycling load. The frontend electronic system consists of a voltage processing unit to attenuate high peak voltages, a rectifier and a regulator to convert the input AC signal into a stabilized DC signal. The DC voltage signal provides biasing for the delta-sigma analog-to-digital converter (ADC). Thus, the output of the triboelectric harvester acts as both the power signal that is rectified/regulated and data signal that is digitized. The power consumption of the proposed PCB design is approximately 5.35 μW. Next, the frontend sensor circuitry is improved to accommodate a wider range of cyclic load. These results demonstrate that triboelectric energy harvesting is a promising technique for self-monitoring the load inside knee implants.

A Smart Knee Implant Using Triboelectric Energy Harvesters

Although the number of total knee replacement (TKR) surgeries is growing rapidly, functionality and pain-reduction outcomes remain unsatisfactory for many patients. Continual monitoring of knee loads after surgery offers the potential to improve surgical procedures and implant designs. The goal of this study is to characterize a triboelectric energy harvester under body loads and to design compatible frontend electronics to digitize the load data. The harvester prototype would be placed between the tibial component and polyethylene bearing of a TKR implant. The harvester generates power from the compressive load. To examine the harvester output and the feasibility of powering a digitization circuitry, a triboelectric energy harvester prototype is fabricated and tested. An axial tibiofemoral load profile from normal walking (gait) is approximated as a 1 Hz sine wave signal and is applied to the harvester. Because the root mean square of voltages generated via this phenomenon is proportional to the applied load, the device can be simultaneously employed for energy harvesting and load sensing. With an approximated knee cyclic load of 2.3 kN at 1 Hz, the harvester generated output voltage of 18 V RMS, and an average power of 6 μW at the optimal resistance of 58MΩ. The harvested signal is rectified through a negative voltage converter rectifier and regulated through a linear-dropout regulator with a combined efficiency of 71%. The output of the regulator is used to charge a supercapacitor. The energy stored in the supercapacitor is used for low resolution sensing of the load through a peak detector and analog-to-digital converter. According to our analysis, sensing the load several times a day is feasible by relying only on harvested power. The results found from this work demonstrate that triboelectric energy harvesting is a promising technique for self-powering load sensors inside knee implants.

Discriminating between generalized anxiety disorder and anxiety disorder not otherwise specified in a Hispanic population: is it only a matter of worry?

One hundred and two Hispanic persons who presented for treatment at a specialized anxiety disorders clinic were evaluated at intake using the Anxiety Disorders Interview Schedule-Revised (ADIS-R; DiNardo and Barlow [1988] Albany: Center for Stress and Anxiety Disorders, State University of New York at Albany). Results indicated that 14% of these patients suffered from anxiety and/or affective disorders that were not adequately captured by our current diagnostic system. Given that the majority of these cases were characterized by predominantly anxious features, further investigation was undertaken to determine the degree of overlap between these patients (anxiety disorder, not otherwise specified; NOS) and those with generalized anxiety disorder (GAD). The two groups differed only with regard to the number of excessive worries they reported and not in terms of somatic symptomatology, psychosocial stressors, or demographic variables. These data suggest that excessive worry may be a discriminating factor between the GAD and NOS groups, providing support for the notion of GAD as a disorder of chromic worry. Future research is needed to tease apart the relative influences of culture and socioeconomic status on our findings.

Cervical aortic arch. A case report

Cervical aortic arch is a rare type of aortic arch anomaly that is presumed to result from persistence of the third aortic arch and regression of the normal fourth arch. Most of the patients with this anomaly are asymptomatic, but symptoms of dysphagia and respiratory distress due to the compression by the vascular ring have been reported. Other findings such as a supraclavicular pulsatile mass, blood pressure discrepancies between the upper limbs, and loss of femoral or opposite-upper-limb pulses with compression of the cervical mass may also be present. In this article a twenty-two-year-old woman with symptomatic cervical aortic arch is presented. The patient had a left cervical pulsatile mass and elevated blood pressure on her right upper limb and was treated surgically with reanastomosis of the aorta.

The effect of selenium added cardioplegia in guinea pigs

1. The aim of the study was to determine the effect of selenium added cardioplegic solutions on postischemic myocardial recovery. 2. The hearts were mounted on Langendorf perfusion apparatus and perfused with Krebs-Henseleit solution. The hearts were arrested by one of the following cardioplegic solutions; (a) K+ 20 mmol/l (control group); (b) K+ 20 mmol/l+selenium 10(-3) mol/l (experimental group). After 20 min of normothermic ischemia the hearts were reperfused by the same buffer. 3. Postischemic percentage changes of heart rate, contractile force and heart work were compared between the groups. 4. Addition of selenium to the cardioplegic solution significantly decreased the postischemic myocardial injury.

Intravenously administered immune globulin for the treatment of infection-associated hemophagocytic syndrome

Infection-associated hemophagocytic syndrome is an unusual disease with a high mortality rate. A variety of treatment modalities have been used with limited success. We report three patients with infection-associated hemophagocytic syndrome successfully treated with intravenously administered immune globulin.

Thromboangiitis obliterans (Buerger's disease) in women (a reevaluation)

Thromboangiitis obliterans (TAO) is an occlusive vascular disease traditionally known to be almost exclusive to young male smokers. The disease was considered to be extremely rare in women, seen only as isolated, novel case reports in the literature. In the past decade, however, a dramatic increase in the incidence of female TAO has been observed. In this paper the authors report 7 cases of clinically and angiographically verified female TAO. The world literature in regard to the diagnostic criteria, changing incidence, and etiology is reviewed. They conclude that the increased use of tobacco among young women in the past two to three decades is responsible for this dramatic change.

Primary muscular hydatid cyst causing arterial insufficiency: case report and literature review

Hydatid disease, though known to occur in most organs and areas of the body, is extremely rare in skeletal muscle. In this article the authors present a case of a primary muscular hydatid cyst, originating from the adductor muscle group, causing obstruction of the femoral artery and vein.