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Chan RJ, Crichton M, Crawford-Williams F, Agbejule OA, Yu K, Hart NH, de Abreu Alves F, Ashbury FD, Eng L, Fitch M, Jain H, Jefford M, Klemanski D, Koczwara B, Loh K, Prasad M, Rugo H, Soto-Perez-de-Celis E, van den Hurk C, Chan A. The efficacy, challenges, and facilitators of telemedicine in post-treatment cancer survivorship care: an overview of systematic reviews. Ann Oncol 2021; 32:1552-1570. [PMID: 34509615 DOI: 10.1016/j.annonc.2021.09.001] [Citation(s) in RCA: 74] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 08/16/2021] [Accepted: 09/03/2021] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND Telemedicine services have been increasingly used to facilitate post-treatment cancer survivorship care, including improving access; monitoring health status, health behaviors, and symptom management; enhancing information exchange; and mitigating the costs of care delivery, especially since the COVID-19 pandemic. To inform guidance for the use of telemedicine in the post-COVID era, the aim of this overview of systematic reviews (SRs) was to evaluate the efficacy of, and survivor engagement in, telemedicine interventions in the post-treatment survivorship phase, and to consider implementation barriers and facilitators. METHODS PubMed, Cochrane CENTRAL, CINAHL, Embase, and Web of Science databases were searched. SRs that examined the use of telemedicine in the post-treatment phase of cancer survivorship, published between January 2010 and April 2021, were included. Efficacy data were synthesized narratively. Implementation barriers and facilitators were synthesized using the Consolidated Framework for Implementation Research. RESULTS Twenty-nine SRs were included. A substantive body of evidence found telemedicine to benefit the management of psychosocial and physical effects, particularly for improving fatigue and cognitive function. There was a lack of evidence on the use of telemedicine in the prevention and surveillance for recurrences and new cancers as well as management of chronic medical conditions. This overview highlights a range of diverse barriers and facilitators at the patient, health service, and system levels. CONCLUSIONS This review highlights the benefits of telemedicine in addressing psychosocial and physical effects, but not in other areas of post-treatment cancer survivorship care. This large review provides practical guidance for use of telemedicine in post-treatment survivorship care.
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Review |
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Jackson JA, Messner MC, Dudukovic NA, Smith WL, Bekker L, Moran B, Golobic AM, Pascall AJ, Duoss EB, Loh KJ, Spadaccini CM. Field responsive mechanical metamaterials. SCIENCE ADVANCES 2018; 4:eaau6419. [PMID: 30539147 PMCID: PMC6286172 DOI: 10.1126/sciadv.aau6419] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2018] [Accepted: 10/10/2018] [Indexed: 05/18/2023]
Abstract
Typically, mechanical metamaterial properties are programmed and set when the architecture is designed and constructed, and do not change in response to shifting environmental conditions or application requirements. We present a new class of architected materials called field responsive mechanical metamaterials (FRMMs) that exhibit dynamic control and on-the-fly tunability enabled by careful design and selection of both material composition and architecture. To demonstrate the FRMM concept, we print complex structures composed of polymeric tubes infilled with magnetorheological fluid suspensions. Modulating remotely applied magnetic fields results in rapid, reversible, and sizable changes of the effective stiffness of our metamaterial motifs.
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Dusitanond P, Eikelboom JW, Hankey GJ, Thom J, Gilmore G, Loh K, Yi Q, Klijn CJM, Langton P, van Bockxmeer FM, Baker R, Jamrozik K. Homocysteine-Lowering Treatment With Folic Acid, Cobalamin, and Pyridoxine Does Not Reduce Blood Markers of Inflammation, Endothelial Dysfunction, or Hypercoagulability in Patients With Previous Transient Ischemic Attack or Stroke. Stroke 2005; 36:144-6. [PMID: 15569860 DOI: 10.1161/01.str.0000150494.91762.70] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background and Purpose—
Epidemiological and laboratory studies suggest that increasing concentrations of plasma homocysteine (total homocysteine [tHcy]) accelerate cardiovascular disease by promoting vascular inflammation, endothelial dysfunction, and hypercoagulability.
Methods—
We conducted a randomized controlled trial in 285 patients with recent transient ischemic attack or stroke to examine the effect of lowering tHcy with folic acid 2 mg, vitamin B
12
0.5 mg, and vitamin B
6
25 mg compared with placebo on laboratory markers of vascular inflammation, endothelial dysfunction, and hypercoagulability.
Results—
At 6 months after randomization, there was no significant difference in blood concentrations of markers of vascular inflammation (high-sensitivity C-reactive protein [
P
=0.32]; soluble CD40L [
P
=0.33]; IL-6 [
P
=0.77]), endothelial dysfunction (vascular cell adhesion molecule-1 [
P
=0.27]; intercellular adhesion molecule-1 [
P
=0.08]; von Willebrand factor [
P
=0.92]), and hypercoagulability (P-selectin [
P
=0.33]; prothrombin fragment 1 and 2 [
P
=0.81]; D-dimer [
P
=0.88]) among patients assigned vitamin therapy compared with placebo despite a 3.7-μmol/L (95% CI, 2.7 to 4.7) reduction in total homocysteine (tHcy).
Conclusions—
Lowering tHcy by 3.7 μmol/L with folic acid-based multivitamin therapy does not significantly reduce blood concentrations of the biomarkers of inflammation, endothelial dysfunction, or hypercoagulability measured in our study. The possible explanations for our findings are: (1) these biomarkers are not sensitive to the effects of lowering tHcy (eg, multiple risk factor interventions may be required); (2) elevated tHcy causes cardiovascular disease by mechanisms other than the biomarkers measured; or (3) elevated tHcy is a noncausal marker of increased vascular risk.
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Hankey GJ, Algra A, Chen C, Wong MC, Cheung R, Wong L, Divjak I, Ferro J, de Freitas G, Gommans J, Groppa S, Hill M, Spence D, Lees K, Lisheng L, Navarro J, Ranawaka U, Ricci S, Schmidt R, Slivka A, Tan K, Tsiskaridze A, Uddin W, Vanhooren G, Xavier D, Armitage J, Hobbs M, Le M, Sudlow C, Wheatley K, Yi Q, Bulder M, Eikelboom JW, Hankey GJ, Ho WK, Jamrozik K, Klijn K, Koedam E, Langton P, Nijboer E, Tuch P, Pizzi J, Tang M, Antenucci M, Chew Y, Chinnery D, Cockayne C, Loh K, McMullin L, Smith F, Schmidt R, Chen C, Wong MC, de Freitas G, Hankey GJ, Loh K, Song S. VITATOPS, the VITAmins TO prevent stroke trial: rationale and design of a randomised trial of B-vitamin therapy in patients with recent transient ischaemic attack or stroke (NCT00097669) (ISRCTN74743444). Int J Stroke 2008; 2:144-50. [PMID: 18705976 DOI: 10.1111/j.1747-4949.2007.00111.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
BACKGROUND Epidemiological studies suggest that raised plasma concentrations of total homocysteine (tHcy) may be a common, causal and treatable risk factor for atherothromboembolic ischaemic stroke, dementia and depression. Although tHcy can be lowered effectively with small doses of folic acid, vitamin B(12) and vitamin B(6), it is not known whether lowering tHcy, by means of B vitamin therapy, can prevent stroke and other major atherothromboembolic vascular events. AIM To determine whether the addition of B-vitamin supplements (folic acid 2 mg, B(6) 25 mg, B(12) 500 microg) to best medical and surgical management will reduce the combined incidence of stroke, myocardial infarction (MI) and vascular death in patients with recent stroke or transient ischaemic attack (TIA) of the brain or eye. DESIGN A prospective, international, multicentre, randomised, double blind, placebo-controlled clinical trial. SETTING One hundred and four medical centres in 20 countries on five continents. SUBJECTS Eight thousand (6600 recruited as of 5 January, 2006) patients with recent (<7 months) stroke (ischaemic or haemorrhagic) or TIA (brain or eye). RANDOMISATION Randomisation and data collection are performed by means of a central telephone service or secure internet site. INTERVENTION One tablet daily of either placebo or B vitamins (folic acid 2 mg, B(6) 25 mg, B(12) 500 mug). PRIMARY OUTCOME The composite of stroke, MI or death from any vascular cause, whichever occurs first. Outcome and serious adverse events are adjudicated blinded to treatment allocation. SECONDARY OUTCOMES TIA, unstable angina, revascularisation procedures, dementia, depression. STATISTICAL POWER: With 8000 patients followed up for a median of 2 years and an annual incidence of the primary outcome of 8% among patients assigned placebo, the study will have at least 80% power to detect a relative reduction of 15% in the incidence of the primary outcome among patients assigned B vitamins (to 6.8%/year), applying a two-tailed level of significance of 5%. CONCLUSION VITATOPS aims to recruit and follow-up 8000 patients between 1998 and 2008, and provide a reliable estimate of the safety and effectiveness of folic acid, vitamin B(12), and vitamin B(6) supplementation in reducing recurrent serious vascular events among a wide range of patients with TIA and stroke throughout the world.
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Dhong C, Miller R, Root NB, Gupta S, Kayser LV, Carpenter CW, Loh KJ, Ramachandran VS, Lipomi DJ. Role of indentation depth and contact area on human perception of softness for haptic interfaces. SCIENCE ADVANCES 2019; 5:eaaw8845. [PMID: 31497646 PMCID: PMC6716960 DOI: 10.1126/sciadv.aaw8845] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Accepted: 07/23/2019] [Indexed: 05/22/2023]
Abstract
In engineering, the "softness" of an object, as measured by an indenter, manifests as two measurable parameters: (i) indentation depth and (ii) contact area. For humans, softness is not well defined, although it is believed that perception depends on the same two parameters. Decoupling their relative contributions, however, has not been straightforward because most bulk-"off-the-shelf"-materials exhibit the same ratio between the indentation depth and contact area. Here, we decoupled indentation depth and contact area by fabricating elastomeric slabs with precise thicknesses and microstructured surfaces. Human subject experiments using two-alternative forced-choice and magnitude estimation tests showed that the indentation depth and contact area contributed independently to perceived softness. We found an explicit relationship between the perceived softness of an object and its geometric properties. Using this approach, it is possible to design objects for human interaction with a desired level of perceived softness.
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Research Support, N.I.H., Extramural |
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Meyers FN, Loh KJ, Dodds JS, Baltazar A. Active sensing and damage detection using piezoelectric zinc oxide-based nanocomposites. NANOTECHNOLOGY 2013; 24:185501. [PMID: 23579369 DOI: 10.1088/0957-4484/24/18/185501] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
This study investigated the design and performance of piezoelectric nanocomposite-based interdigitated transducers (IDTs) for active sensing and damage detection. First, thin films that are highly piezoelectric and mechanically flexible were designed by embedding zinc oxide (ZnO) nanoparticles in a poly(vinylidene fluoride-trifluoroethylene) (PVDF-TrFE) piezo-polymer matrix. Second, the suspended nanoparticle solutions were then spin coated onto patterned comb electrodes to fabricate the IDTs. The films were then poled to align their electric domains and to increase their permanent piezoelectricity. Upon IDT fabrication, its sensing and actuation of Lamb waves on an aluminum pipe was validated. These results were also compared to data obtained from commercial Macro Fiber Composite IDT transducers. In the last phase of this work, damage detection was demonstrated by mounting these nanocomposite sensors and actuators (using a pitch-catch setup) onto an aluminum pipe and plate. Damage was simulated by tightening a band clamp around the pipe and by drilling holes in the plate. A damage index calculation was used to compare results corresponding to different levels of damage applied to the plate (i.e., different drilled hole depths), and good correlation was observed. Thus, ZnO/PVDF-TrFE transducers were shown to have the potential for use as piezoelectric transducers for structural health monitoring and damage detection.
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Chung HC, Enomoto T, Loh K, Shinozuka M. Real-time visualization of bridge structural response through wireless MEMS sensors. ACTA ACUST UNITED AC 2004. [DOI: 10.1117/12.539263] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
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Qi Y, Purtell L, Fu M, Sengmany K, Loh K, Zhang L, Zolotukhin S, Sainsbury A, Campbell L, Herzog H. Ambient temperature modulates the effects of the Prader-Willi syndrome candidate gene Snord116 on energy homeostasis. Neuropeptides 2017; 61:87-93. [PMID: 27823858 DOI: 10.1016/j.npep.2016.10.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Revised: 10/18/2016] [Accepted: 10/24/2016] [Indexed: 02/05/2023]
Abstract
Germline deletion of the Prader-Willi syndrome (PWS) candidate gene Snord116 in mice leads to some classical symptoms of human PWS, notably reductions in body weight, linear growth and bone mass. However, Snord116 deficient mice (Snord116-/-) do not develop an obese phenotype despite their increased food intake and the underlying mechanism for that is unknown. We tested the phenotypes of germline Snord116-/- as well as neuropeptide Y (NPY) neuron specific Snord116lox/lox/NPYcre/+ mice at 30°C, the thermoneutral temperature of mice, and compared these to previous reports studies conducted at normal room temperature. Snord116-/- mice at 30°C still weighed less than wild type but had increased body weight gain. Importantly, food intake and energy expenditure were no longer different at 30°C, and the reduced bone mass and nasal-anal length observed in Snord116-/- mice at room temperature were also normalized. Mechanistically, the thermoneutral condition led to the correction of the mRNA expression of NPY and pro-opiomelanocortin (POMC), which were both previously observed to be significantly up-regulated at room temperature. Importantly, almost identical phenotypes and NPY/POMC mRNA expression alterations were also observed in Snord116lox/lox/NPYcre/+ mice, which lack the Snord116 gene only in NPY neurons. These data illustrate that mild cold stress is a critical factor preventing the development of obesity in Snord116-/- mice via the NPY system. Our study highlights that the function of Snord116 in the hypothalamus may be to enhance energy expenditure, likely via the NPY system, and also indicates that Snord116 function in mice is strongly dependent on environmental conditions such as cold exposure.
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Gupta S, Loh KJ, Pedtke A. Sensing and actuation technologies for smart socket prostheses. Biomed Eng Lett 2019; 10:103-118. [PMID: 32175132 DOI: 10.1007/s13534-019-00137-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 10/17/2019] [Accepted: 10/26/2019] [Indexed: 01/20/2023] Open
Abstract
The socket is the most critical part of every lower-limb prosthetic system, since it serves as the interfacial component that connects the residual limb with the artificial system. However, many amputees abandon their socket prostheses due to the high-level of discomfort caused by the poor interaction between the socket and residual limb. In general, socket prosthesis performance is determined by three main factors, namely, residual limb-socket interfacial stress, volume fluctuation of the residual limb, and temperature. This review paper summarizes the various sensing and actuation solutions that have been proposed for improving socket performance and for realizing next-generation socket prostheses. The working principles of different sensors and how they have been tested or used for monitoring the socket interface are discussed. Furthermore, various actuation methods that have been proposed for actively modifying and improving the socket interface are also reviewed. Through the continued development and integration of these sensing and actuation technologies, the long-term vision is to realize smart socket prostheses. Such smart socket systems will not only function as a socket prosthesis but will also be able to sense parameters that cause amputee discomfort and self-adjust to optimize its fit, function, and performance.
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Review |
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Hankey GJ, Eikelboom JW, Loh K, Tang M, Pizzi J, Thom J, Yi Q. Sustained Homocysteine-Lowering Effect over Time of Folic Acid-Based Multivitamin Therapy in Stroke Patients despite Increasing Folate Status in the Population. Cerebrovasc Dis 2005; 19:110-6. [PMID: 15608435 DOI: 10.1159/000082788] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2004] [Accepted: 08/11/2004] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND AND AIMS It is uncertain what impact increasing voluntary folate fortification may be having on the statistical power of randomized trials testing the homocysteine hypothesis of atherothrombosis. The objective of this study was to determine whether there has been a change in folate status between 1998 and 2002 in stroke patients randomized into the VITAmins TO Prevent Stroke (VITATOPS) Study at a single center in Perth, Australia, and what impact this may have had on the magnitude of the homocysteine-lowering effect achieved over time with folic acid-based multivitamin therapy. METHODS We conducted a randomized, double-blind, placebo-controlled study involving 285 patients with stroke or transient ischemic attack who were recruited between 1998 and 2002 and randomized to long-term folic acid 2.0 mg/day, pyridoxine 25 mg/day and cobalamin 0.5 mg/day (active VITATOPS medication) or placebo. Fasting plasma total homocysteine, red cell folate, serum cobalamin and serum pyridoxine levels were measured at baseline and 6 months, and the change in blood levels over 4 time quartiles and differences in levels between the two randomized treatments were examined. RESULTS Between 1998 and 2002, there was a significant rise in baseline mean red cell folate levels over 4 time quartiles among the entire stroke cohort (723.3, 780.1, 922.6 and 1,023.7 nmol/l in the first, second, third and fourth quartiles, respectively; p < 0.0001), but this was not associated with a spontaneous reduction in mean baseline total homocysteine levels during the same time period (12.7, 14.3, 12.1 and 12.8 micromol/l in the first, second, third and fourth quartiles, respectively; p = 0.55). The homocysteine-lowering effect of the active VITATOPS trial medication at 6 months after randomization also did not change significantly between 1998 and 2002 (difference between randomized groups: -4.1, -4.1, -3.1 and -3.6 micromol/l in the first, second, third and fourth quartiles, respectively; p = 0.56). CONCLUSIONS The homocysteine-lowering effect of the active VITATOPS trial medication has not attenuated significantly in the past 5 years despite increasing voluntary fortification of foods with folic acid as reflected by a progressive rise in baseline folate status. These data suggest that in the continuing absence of a program of mandatory folate fortification of food in populations served by centers participating in the VITATOPS trial, the study will remain adequately powered to test the homocysteine-lowering hypothesis for which it was designed.
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Park Y, Vella G, Loh KJ. Bio-Inspired Active Skins for Surface Morphing. Sci Rep 2019; 9:18609. [PMID: 31819136 PMCID: PMC6901544 DOI: 10.1038/s41598-019-55163-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Accepted: 11/25/2019] [Indexed: 02/06/2023] Open
Abstract
Mechanical metamaterials that leverage precise geometrical designs and imperfections to induce unique material behavior have garnered significant attention. This study proposes a Bio-Inspired Active Skin (BIAS) as a new class of instability-induced morphable structures, where selective out-of-plane material deformations can be pre-programmed during design and activated by in-plane strains. The deformation mechanism of a unit cell geometrical design is analyzed to identify how the introduction of hinge-like notches or instabilities, versus their pristine counterparts, can pave way for controlling bulk BIAS behavior. Two-dimensional arrays of repeating unit cells were fabricated, with notches implemented at key locations throughout the structure, to harvest the instability-induced surface features for applications such as camouflage, surface morphing, and soft robotic grippers.
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Gupta S, Loh KJ. Noncontact Electrical Permittivity Mapping and pH-Sensitive Films for Osseointegrated Prosthesis and Infection Monitoring. IEEE TRANSACTIONS ON MEDICAL IMAGING 2017; 36:2193-2203. [PMID: 28541895 DOI: 10.1109/tmi.2017.2707390] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The objective of this paper is to develop a noncontact, noninvasive system for detecting and monitoring subcutaneous infection occurring at the tissue and osseointegrated prosthesis interface. It is known that the local pH of tissue can change due to infection. Therefore, the sensing system integrates two parts, namely, pH-sensitive thin films that can be coated onto prosthesis surfaces prior to them being implanted and an electrical capacitance tomography (ECT) algorithm that can reconstruct the spatial permittivity distribution of a region of space in a noncontact fashion. First, a thin film pH sensor was fabricated by spray coating, and tests confirmed that the film exhibited changes in its permittivity due to pH. Second, the ECT forward and inverse problems were implemented. Third, an aluminum rod was employed as a representative phantom of an osseointegrated prosthesis and then spray coated with the pH sensor. Finally, the film-coated phantom was immersed in different pH buffers, dried, and subjected to ECT interrogation and spatial permittivity reconstruction. The results validated that ECT was able to detect and localize permittivity variations correlated to pH changes.
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Gupta S, Lee HJ, Loh KJ, Todd MD, Reed J, Barnett AD. Noncontact Strain Monitoring of Osseointegrated Prostheses. SENSORS (BASEL, SWITZERLAND) 2018; 18:E3015. [PMID: 30205608 PMCID: PMC6164507 DOI: 10.3390/s18093015] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/24/2018] [Revised: 08/12/2018] [Accepted: 09/06/2018] [Indexed: 11/17/2022]
Abstract
The objective of this study was to develop a noncontact, noninvasive, imaging system for monitoring the strain and deformation states of osseointegrated prostheses. The proposed sensing methodology comprised of two parts. First, a passive thin film was designed such that its electrical permittivity increases in tandem with applied tensile loading and decreases while unloading. It was found that patterning the thin films could enhance their dielectric property's sensitivity to strain. The film can be deposited onto prosthesis surfaces as an external coating prior to implant. Second, an electrical capacitance tomography (ECT) measurement technique and reconstruction algorithm were implemented to capture strain-induced changes in the dielectric property of nanocomposite-coated prosthesis phantoms when subjected to different loading scenarios. The preliminary results showed that ECT, when coupled with strain-sensitive nanocomposites, could quantify the strain-induced changes in the dielectric property of thin film-coated prosthesis phantoms. The results suggested that ECT coupled with embedded thin films could serve as a new noncontact strain sensing method for scenarios when tethered strain sensors cannot be used or instrumented, especially in the case of osseointegrated prostheses.
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Hankey GJ, Eikelboom JW, Loh K, Yi Q, Pizzi J, Tang M, Hickling S, Le M, Klijn CJM, Dusitanond P, van Bockxmeer F, Gelavis A, Baker R, Jamrozik K. Is There Really a Power Shortage in Clinical Trials Testing the “Homocysteine Hypothesis?”. Arterioscler Thromb Vasc Biol 2004; 24:e147. [PMID: 15297291 DOI: 10.1161/01.atv.0000136385.50973.68] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Lee HJ, Prachaseree P, Loh KJ. Rapid Soft Material Actuation Through Droplet Evaporation. Soft Robot 2020; 8:555-563. [PMID: 32833572 DOI: 10.1089/soro.2020.0055] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Soft material actuation is a promising field that can potentially solve several limitations of traditional robotic systems. These systems comprise soft and flexible materials to achieve high degrees of freedom and compliance with their surroundings. One method to actuate such structures is to vaporize liquid that is embedded inside the soft material. The soft elastomers are inflated since the generated vapor occupies a much larger volume after phase transformation. The simplest and widely used design to vaporize such liquids is installing a heating element near the liquid. Heating the system beyond the boiling point rapidly boils the liquid and deforms the structure. However, this technique possesses several limitations, such as the heating element must be in the liquid's vicinity, and boiling the liquid requires high temperatures. In addition, embedding a small amount of liquid for faster boiling prevents the use of valves to exhaust the vapor. Instead, the structure is slowly cooled until it returns to its original position. In this study, these limitations are addressed by combining heating with vibrating mesh atomization. The atomizer disperses the liquid into small droplets, which vaporize much faster as compared with simply heating the bulk liquid. Actuation through vibrating mesh atomization was first characterized and compared with other techniques. Then, the introduced method was used to demonstrate cyclic actuation, and a bistable structure was designed and fabricated to demonstrate gripping motion.
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Wang L, Loh KJ, Chiang WH, Manna K. Micro-patterned graphene-based sensing skins for human physiological monitoring. NANOTECHNOLOGY 2018; 29:105503. [PMID: 29324440 DOI: 10.1088/1361-6528/aaa709] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Ultrathin, flexible, conformal, and skin-like electronic transducers are emerging as promising candidates for noninvasive and nonintrusive human health monitoring. In this work, a wearable sensing membrane is developed by patterning a graphene-based solution onto ultrathin medical tape, which can then be attached to the skin for monitoring human physiological parameters and physical activity. Here, the sensor is validated for monitoring finger bending/movements and for recognizing hand motion patterns, thereby demonstrating its future potential for evaluating athletic performance, physical therapy, and designing next-generation human-machine interfaces. Furthermore, this study also quantifies the sensor's ability to monitor eye blinking and radial pulse in real-time, which can find broader applications for the healthcare sector. Overall, the printed graphene-based sensing skin is highly conformable, flexible, lightweight, nonintrusive, mechanically robust, and is characterized by high strain sensitivity.
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Zhao Y, Schagerl M, Viechtbauer C, Loh KJ. Characterizing the Conductivity and Enhancing the Piezoresistivity of Carbon Nanotube-Polymeric Thin Films. MATERIALS 2017; 10:ma10070724. [PMID: 28773084 PMCID: PMC5551767 DOI: 10.3390/ma10070724] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Revised: 06/22/2017] [Accepted: 06/22/2017] [Indexed: 11/29/2022]
Abstract
The concept of lightweight design is widely employed for designing and constructing aerospace structures that can sustain extreme loads while also being fuel-efficient. Popular lightweight materials such as aluminum alloy and fiber-reinforced polymers (FRPs) possess outstanding mechanical properties, but their structural integrity requires constant assessment to ensure structural safety. Next-generation structural health monitoring systems for aerospace structures should be lightweight and integrated with the structure itself. In this study, a multi-walled carbon nanotube (MWCNT)-based polymer paint was developed to detect distributed damage in lightweight structures. The thin film’s electromechanical properties were characterized via cyclic loading tests. Moreover, the thin film’s bulk conductivity was characterized by finite element modeling.
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Gupta S, Loh KJ. Monitoring osseointegrated prosthesis loosening and fracture using electrical capacitance tomography. Biomed Eng Lett 2019; 8:291-300. [PMID: 30603213 DOI: 10.1007/s13534-018-0073-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2018] [Revised: 04/05/2018] [Accepted: 05/15/2018] [Indexed: 11/28/2022] Open
Abstract
A noncontact, noninvasive, electrical permittivity imaging technique is proposed for monitoring loosening of osseointegrated prostheses and bone fracture. The proposed method utilizes electrical capacitance tomography (ECT), which employs a set of noncontact electrodes, arranged in a circular fashion around the imaging area, for electrical excitations and measurements. An inverse reconstruction algorithm was developed and implemented to reconstruct the electrical permittivity distribution of the interrogated region from boundary capacitance measurements. In this study, osseointegrated prosthesis phantoms were prepared using plastic rods and Sawbone femur specimens, which were subjected to prosthesis loosening and fracture monitoring tests. The results demonstrated that the spatial location and extent of prosthesis loosening and bone fracture could be estimated from the ECT reconstructed permittivity maps. The resolution of the reconstructed images was further enhanced by a limited region tomography algorithm, and its accuracy in terms of identifying the severity, location, and shape of bone fracture was also investigated and compared with conventional full region tomography.
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Lee BM, Loh KJ. Carbon nanotube thin film strain sensors: comparison between experimental tests and numerical simulations. NANOTECHNOLOGY 2017; 28:155502. [PMID: 28244878 DOI: 10.1088/1361-6528/aa6382] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Carbon nanotubes can be randomly deposited in polymer thin film matrices to form nanocomposite strain sensors. However, a computational framework that enables the direct design of these nanocomposite thin films is still lacking. The objective of this study is to derive an experimentally validated and two-dimensional numerical model of carbon nanotube-based thin film strain sensors. This study consisted of two parts. First, multi-walled carbon nanotube (MWCNT)-Pluronic strain sensors were fabricated using vacuum filtration, and their physical, electrical, and electromechanical properties were evaluated. Second, scanning electron microscope images of the films were used for identifying topological features of the percolated MWCNT network, where the information obtained was then utilized for developing the numerical model. Validation of the numerical model was achieved by ensuring that the area ratios (of MWCNTs relative to the polymer matrix) were equivalent for both the experimental and modeled cases. Strain sensing behavior of the percolation-based model was simulated and then compared to experimental test results.
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Lin YA, Mhaskar Y, Silder A, Sessoms PH, Fraser JJ, Loh KJ. Muscle Engagement Monitoring Using Self-Adhesive Elastic Nanocomposite Fabrics. SENSORS (BASEL, SWITZERLAND) 2022; 22:6768. [PMID: 36146120 PMCID: PMC9503620 DOI: 10.3390/s22186768] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/21/2022] [Revised: 09/04/2022] [Accepted: 09/06/2022] [Indexed: 06/16/2023]
Abstract
Insight into, and measurements of, muscle contraction during movement may help improve the assessment of muscle function, quantification of athletic performance, and understanding of muscle behavior, prior to and during rehabilitation following neuromusculoskeletal injury. A self-adhesive, elastic fabric, nanocomposite, skin-strain sensor was developed and validated for human movement monitoring. We hypothesized that skin-strain measurements from these wearables would reveal different degrees of muscle engagement during functional movements. To test this hypothesis, the strain sensing properties of the elastic fabric sensors, especially their linearity, stability, repeatability, and sensitivity, were first verified using load frame tests. Human subject tests conducted in parallel with optical motion capture confirmed that they can reliably measure tensile and compressive skin-strains across the calf and tibialis anterior. Then, a pilot study was conducted to assess the correlation of skin-strain measurements with surface electromyography (sEMG) signals. Subjects did biceps curls with different weights, and the responses of the elastic fabric sensors worn over the biceps brachii and flexor carpi radialis (i.e., forearm) were well-correlated with sEMG muscle engagement measures. These nanocomposite fabric sensors were validated for monitoring muscle engagement during functional activities and did not suffer from the motion artifacts typically observed when using sEMGs in free-living community settings.
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Loh K, Matthay KK, Hoover M, Bracho FA, Cortez AB, Conte FA, Albanese CT, Miller TR, Price DC, Flores AJ, Kaviani A, Shoback D. Hypercalcemia in malignant paraganglioma due to parathyroid hormone-related protein. HORMONE RESEARCH 2000; 50:217-21. [PMID: 9838243 DOI: 10.1159/000023277] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
A 15-year-old boy had hypercalcemia in association with malignant retroperitoneal paraganglioma. He had suppressed circulating levels of intact parathyroid hormone, whereas parathyroid hormone-related protein (PTHrP) immunoreactivity was elevated in plasma. Both the serum 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D levels were normal. Preoperatively the patient required control of hypercalcemia with intravenous pamidronate therapy. His circulating calcium and PTHrP concentrations became normal after a successful surgical resection of the primary retroperitoneal tumor. To our knowledge, this is the first reported case of elevated PtHrP levels in a patient with paraganglioma which resolved postoperatively.
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Shu Y, Mukherjee S, Chang T, Gilmore A, Tringe JW, Stobbe DM, Loh KJ. Multi-Defect Detection in Additively Manufactured Lattice Structures Using 3D Electrical Resistance Tomography. SENSORS (BASEL, SWITZERLAND) 2022; 22:9167. [PMID: 36501867 PMCID: PMC9736320 DOI: 10.3390/s22239167] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 11/19/2022] [Accepted: 11/22/2022] [Indexed: 06/17/2023]
Abstract
Cellular lattice structures possess high strength-to-weight ratios suitable for advanced lightweight engineering applications. However, their quality and mechanical performance can degrade because of defects introduced during manufacturing or in-service. Their complexity and small length scale features make defects difficult to detect using conventional nondestructive evaluation methods. Here we propose a current injection-based method, electrical resistance tomography (ERT), that can be used to detect damaged struts in conductive cellular lattice structures with their intrinsic electromechanical properties. The reconstructed conductivity distributions from ERT can reveal the severity and location of damaged struts without having to probe each strut. However, the low central sensitivity of ERT may result in image artifacts and inaccurate localization of damaged struts. To address this issue, this study introduces an absolute, high throughput, conductivity reconstruction algorithm for 3D ERT. The algorithm incorporates a strut-based normalized sensitivity map to compensate for lower interior sensitivity and suppresses reconstruction artifacts. Numerical simulations and experiments on fabricated representative cellular lattice structures were performed to verify the ability of ERT to quantitatively identify single and multiple damaged struts. The improved performance of this method compared with classical ERT was observed, based on greatly decreased imaging and reconstructed value errors.
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Lee HJ, Guerra-Bravo E, Baltazar A, Loh KJ. Atomization Control to Improve Soft Actuation Through Vaporization. Front Robot AI 2021; 8:747440. [PMID: 34540907 PMCID: PMC8446441 DOI: 10.3389/frobt.2021.747440] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Accepted: 08/19/2021] [Indexed: 11/13/2022] Open
Abstract
Soft actuation through droplet evaporation has significantly improved the actuation speed of methods that utilize liquid vaporization. Instead of boiling bulk liquid, this method implements atomization to disperse small droplets into a heater. Due to the large surface area of the droplets, the liquid evaporates much faster even at small temperature changes. However, further analysis is required to maximize the performance of this complex multi-physics method. This study was conducted to provide further insight into the atomizer and how it affects actuation. Numerical simulations were used to inspect the vibration modes and determine how frequency and voltage affect the atomization process. These results were used to experimentally control the atomizer, and the droplet growth on the heater surface was analyzed to study the evaporation process. A cuboid structure was inflated with the actuator to demonstrate its performance. The results show that simply maximizing the atomization rate creates large droplets on the surface of the heater, which slows down the vaporization process. Thus, an optimal atomization rate should be determined for ideal performance.
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Salvino L, Chiu WK, Lynch J, Loh KJ. Special issue of biomedical engineering letters on advances in intelligent prostheses. Biomed Eng Lett 2020; 10:1-3. [PMID: 32175126 PMCID: PMC7046915 DOI: 10.1007/s13534-020-00150-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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Editorial |
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Vaughn CB, McKelvey E, Balcerzak SP, Loh K, Stephens R, Baker L. High-dose methotrexate with leucovorin rescue plus vincristine in advanced sarcoma: a Southwest Oncology Group study. CANCER TREATMENT REPORTS 1984; 68:409-410. [PMID: 6607770] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Twenty-six evaluable patients with advanced soft tissue and bony sarcomas refractory to chemotherapy were treated with vincristine plus high-dose methotrexate and leucovorin rescue. A 14% response rate was observed among 14 patients presenting with refractory soft tissue sarcomas. No responses were observed among 12 patients with bony sarcoma. Toxic reaction with nausea, vomiting, nephrotoxicity, and myelosuppression was manageable. While this study did demonstrate activity of this regimen in doxorubicin-refractory patients, the duration of the responses was relatively brief. Thus, the clinical utility of such a regimen is questionable.
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