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Metasurface-based lenses (metalenses) offer specific conceptual advantages compared to ordinary refractive lenses. For example, it is possible to tune the focal length of a metalens doublet by varying the relative angle between the two metalenses while fixing their distance, leading to an extremely compact zoom lens. An improved polarization-insensitive design based on silicon-nanocylinders on silica substrates is presented. This design is realized and characterized experimentally at 1550 nm wavelength. By varying the relative angle between the metalenses in steps of 10 degrees, tuning of the doublet focal length is demonstrated from −54 mm to ±3 mm to +54 mm. This results in a zoom factor of an imaging system varying between 1 and 18. For positive focal lengths, the doublet focusing efficiency has a minimum of 34% and a maximum of 83%. Experiment and theory are in very good agreement.

This paper describes work we have done in developing an insertable surgical imaging device with multiple degrees-of-freedom for minimally invasive surgery. The device is fully insertable into the abdomen using standard 12mm trocars. It consists of a modular camera and lens system which has pan and tilt capability provided by 2 small DC servo motors. It also has its own integrated lighting system that is part of the camera assembly. Once the camera is inserted into the abdomen, the insertion port is available for additional tooling, motivating the idea of single port surgery. A third zoom axis has been designed for the camera as well, allowing close-up and faraway imaging of surgical sites with a single camera unit. In animal tests with the device we have performed surgical procedures including cholecystectomy, appendectomy, running (measuring) the bowel, suturing, and nephrectomy. The tests show that the new device is:

Biomechanical model of soft tissue derived from experimental measurements is critical for developing a reality-based model for minimally invasive surgical training and simulation. In our research, we have focused on developing a biomechanical model of the liver with the ultimate goal of using this model for local tool-tissue interaction tasks and providing feedback to the surgeon through a haptic display. We are interested in finding the local effective elastic modulus (LEM) of the liver tissue under different strain rates. We have developed a tissue indentation equipment for characterizing the biomechanical properties of the liver and compared the local effective elastic modulus (LEM) derived from experimental data with plane stress, plane strain, and axisymmetric element types in ABAQUS under varying strain rates. Our results show that the experimentally derived local effective modulus matches closely with the plane stress analysis in ABAQUS.

Cell fate determination factor dachshund1 (DACH1) is a chromosome-associated protein that regulates cellular differentiation throughout development. Recent genome-wide association studies have show that missense mutation in DACH1 leads to hereditary renal hypodysplasia. Renal DACH1 expression can be used to estimate glomerular filtration rate (eGFR). We firstly characterized the function of DACH1 in normal and diseased renal tissue using immunohistochemistry to assess DACH1 in human renal biopsy specimens from 40 immunoglobulin A nephropathy (IgAN) patients, 20 idiopathic membranous nephropathy (IMN) patients, and 15 minimal change disease (MCD) patients. We found that DACH1 expression was decreased in the nephropathy group relative to healthy controls. DACH1 staining in the glomerulus correlated positively with eGFR (r = 0.41, p < 0.001) but negatively with serum creatinine (r = −0.37, p < 0.01). In vitro, DACH1 overexpression in human podocytes or HK2 cells decreased expression of cyclin D1, but increased expression of p21 and p53, which suggested that DACH1 overexpression in human podocytes or HK2 cells increased the G1/S phase or G2/M cell arrest. Together, These findings indicate that DACH1 expression is decreased in glomerulopathy imply a potential role for DACH1 in the this development of human chornic glomerulopathy. These data suggest that DACH1 is a potential a marker of disease progression and severity for glomerular diseases.

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Abstract.One of the limitations of current surgical robots used in surgery is the lack of haptic feedback. While current surgical robots improve surgeon dexterity, decrease tremor, and improve visualization, they lack the necessary fidelity to help a surgeon characterize tissue properties for improving diagnostic capabilities. Our work focuses on the development of tools and software that will allow haptic feedback to be integrated in a robot-assisted gastrointestinal surgical procedure. In this paper, we have developed several tissue samples in our laboratory with varying hardness to replicate real-tissues palpated by a surgeon in gastrointestinal procedures. Using this tissue, we have developed a novel setup whereby the tactile feedback from the laparoscopic tool is displayed on the PHANToM haptic interface device in real-time. This is used for tissue characterization and classification. Several experiments were performed with different users and they were asked to identify the tissues. The results demonstrate the feasibility of our approach.

Abstract. Biomechanical model of soft tissue for remote probing based on observed experimental data is critical for developing a reality-based model for minimally invasive surgical training and simulation. In our research, we have focused on developing a biomechanical model of the liver with the ultimate goal of using this model for local tool-tissue interaction tasks and providing feedback through a haptic display. We have designed and developed tissue indentation equipment for characterizing the biomechanical properties of the liver and formulated a hybrid nonlinear model that is valid in both low strain and high strain regions. The pig liver is simplified as the incompressible, isotropic, and homogeneous elastic material. This model will be the basis for a finite element model for the pig liver.