Dry adhesives inspired from climbing animals, such as geckos and spiders, rely on van der Waals forces to attach to the opposing surface. Biological fibrillar dry adhesives have a hierarchical structure closely resemb...Dry adhesives inspired from climbing animals, such as geckos and spiders, rely on van der Waals forces to attach to the opposing surface. Biological fibrillar dry adhesives have a hierarchical structure closely resembling a tree： the surface of the skin on the animal＇s feet is covered in arrays of slender micro-fibrils, each of which supports arrays of fibrils in submicron dimensions. These nano-meter size fibrils can conform closely to the opposing surfaces to induce van der Waals interaction. Bioinspired dry adhesives have been developed in research laboratories for more than a decade. To mimic the biological fibrillar adhesives, fibrillar structures have been prepared using a variety of materials and geometrical arrangements. In this review article, the mechanism and selected fabrication methods of fibrillar adhesives are summarized for future reference in adhesive development. Robotic applications of these bioinspired adhesives are also introduced in this article. Various successful appli- cations of bioinspired fibrillar adhesives can shed light on developing smart adhesives for use in automation.展开更多
In this paper we present a method to create a hydrophobicity gradient on the surface of a Polydimethylsiloxane （PDMS） dry adhesive. The method consists of the partial silanization of the surface of the dry adhesive ...In this paper we present a method to create a hydrophobicity gradient on the surface of a Polydimethylsiloxane （PDMS） dry adhesive. The method consists of the partial silanization of the surface of the dry adhesive by Chemical Vapour Deposition （CVD） of octadecyltrichlorosilane （OTS）. The partial silanization of the surface of the sample results in a hydrophobic to hy- drophilic gradient across the surface of the dry adhesive. The resulting change in hydrophobicity across the surface of the dry adhesive results in the uphill motion of a droplet of water, which appears to be directly proportional to the area of contact between the droplet and the adhesive. Normal adhesion testing is performed to quantify the effect of the hydrophobic gradient across the surface of the sample. While a variation in adhesion are only minimally affected by the silanization, and the motion strength across the sample is measured, the adhesive properties of the droplet of water doesn＇t cause any loss of adhesion.展开更多
OBJECTIVES: This study was designed to assess the impact of prevention of bradycardia with physiologic pacing on the severity of obstructive sleep apnea. BACKGROUND: Apneic episodes during sleep are associated with sl...OBJECTIVES: This study was designed to assess the impact of prevention of bradycardia with physiologic pacing on the severity of obstructive sleep apnea. BACKGROUND: Apneic episodes during sleep are associated with slowing of the heart rate during apnea and tachycardia with subsequent arousal. Patients with permanent pacemakers may have reduced episodes of sleep apnea when their pacemaker rate is set faster than their spontaneous nocturnal heart rate. METHODS: We conducted a prospective, randomized, single-blind crossover trial of temporary atrial pacing in obstructive sleep apnea to reduce the apnea hypopnea index(AHI). Fifteen patients(age 60± 13 years, 12 men) with moderate to severe obstructive sleep apnea(AHI 34± 14) underwent insertion of an externalized atrial permanent pacing system via the left subclavian vein. Patients underwent overnight respiratory sleep studies in hospital, during atrial pacing at 75 beats/min, and with pacing turned off. The order of pacing mode was randomized, with crossover the subsequent night to the other mode. Patients were blinded to pacing mode, and the analysis of sleep recordings was blind to pacing mode. RESULTS: Pacing was tolerated without complications in all patients. Overnight physiologic pacing did not affect the AHI(pacing 39± 21/h vs. control 42± 21/h, p=0.23, 95% confidence interval- 9.3 to 2.5 for difference), desaturation time(pacing 3.8± 6.0% vs. control 3.5± 4.3% , p=0.70), or the minimum SaO2(pacing 75± 10% vs. control 77± 11% , p=0.38). There was a borderline significant reduction in circulatory time with pacing(pacing 23.4± 3.2 s vs. control 25.5± 4.4 s, p=0.09). CONCLUSIONS: Temporary atrial pacing does not appear to improve respiratory manifestations of obstructive sleep apnea. Permanent atrial pacing in this patient population does not appear to be justified.展开更多
文摘Dry adhesives inspired from climbing animals, such as geckos and spiders, rely on van der Waals forces to attach to the opposing surface. Biological fibrillar dry adhesives have a hierarchical structure closely resembling a tree： the surface of the skin on the animal＇s feet is covered in arrays of slender micro-fibrils, each of which supports arrays of fibrils in submicron dimensions. These nano-meter size fibrils can conform closely to the opposing surfaces to induce van der Waals interaction. Bioinspired dry adhesives have been developed in research laboratories for more than a decade. To mimic the biological fibrillar adhesives, fibrillar structures have been prepared using a variety of materials and geometrical arrangements. In this review article, the mechanism and selected fabrication methods of fibrillar adhesives are summarized for future reference in adhesive development. Robotic applications of these bioinspired adhesives are also introduced in this article. Various successful appli- cations of bioinspired fibrillar adhesives can shed light on developing smart adhesives for use in automation.
文摘In this paper we present a method to create a hydrophobicity gradient on the surface of a Polydimethylsiloxane （PDMS） dry adhesive. The method consists of the partial silanization of the surface of the dry adhesive by Chemical Vapour Deposition （CVD） of octadecyltrichlorosilane （OTS）. The partial silanization of the surface of the sample results in a hydrophobic to hy- drophilic gradient across the surface of the dry adhesive. The resulting change in hydrophobicity across the surface of the dry adhesive results in the uphill motion of a droplet of water, which appears to be directly proportional to the area of contact between the droplet and the adhesive. Normal adhesion testing is performed to quantify the effect of the hydrophobic gradient across the surface of the sample. While a variation in adhesion are only minimally affected by the silanization, and the motion strength across the sample is measured, the adhesive properties of the droplet of water doesn＇t cause any loss of adhesion.
文摘OBJECTIVES: This study was designed to assess the impact of prevention of bradycardia with physiologic pacing on the severity of obstructive sleep apnea. BACKGROUND: Apneic episodes during sleep are associated with slowing of the heart rate during apnea and tachycardia with subsequent arousal. Patients with permanent pacemakers may have reduced episodes of sleep apnea when their pacemaker rate is set faster than their spontaneous nocturnal heart rate. METHODS: We conducted a prospective, randomized, single-blind crossover trial of temporary atrial pacing in obstructive sleep apnea to reduce the apnea hypopnea index(AHI). Fifteen patients(age 60± 13 years, 12 men) with moderate to severe obstructive sleep apnea(AHI 34± 14) underwent insertion of an externalized atrial permanent pacing system via the left subclavian vein. Patients underwent overnight respiratory sleep studies in hospital, during atrial pacing at 75 beats/min, and with pacing turned off. The order of pacing mode was randomized, with crossover the subsequent night to the other mode. Patients were blinded to pacing mode, and the analysis of sleep recordings was blind to pacing mode. RESULTS: Pacing was tolerated without complications in all patients. Overnight physiologic pacing did not affect the AHI(pacing 39± 21/h vs. control 42± 21/h, p=0.23, 95% confidence interval- 9.3 to 2.5 for difference), desaturation time(pacing 3.8± 6.0% vs. control 3.5± 4.3% , p=0.70), or the minimum SaO2(pacing 75± 10% vs. control 77± 11% , p=0.38). There was a borderline significant reduction in circulatory time with pacing(pacing 23.4± 3.2 s vs. control 25.5± 4.4 s, p=0.09). CONCLUSIONS: Temporary atrial pacing does not appear to improve respiratory manifestations of obstructive sleep apnea. Permanent atrial pacing in this patient population does not appear to be justified.
