Haptic devices present digital data in a tactile form. That means haptic displays rely on the human sense of touch to convey meaningful data: some haptic devices vibrate, others transmit temperature and still others model virtual shapes and surface tensions.
This allows us to model a data set in virtual space and then touch it. Instead of just looking at the model, with a haptic device we can also feel it: feel it's shape, whether it's hard or soft, slippery or sticky, large or small. We can add inertia to our virtual model, move it around, and feel if it is heavy or light. Even though our virtual model does not exist in real space, using a haptic device we can feel it, and because our model is digital we can control what it feels like.
By writing customized software for a haptic device, we can model surgical procedures, "feel" molecular structures, or mimic an infinite variety of other events which have a dimension involving touch, which holds a great deal of promise in the areas of surgical simulation and biological instruction.
The Massachusetts Institute of Technology (MIT) has developed the first commercial haptic device: the Phantom, from SensAble™ Technologies. In the Phantom, a computer program controls small, highly responsive electric motors which can convey startlingly realistic sensations of touch in three dimensions.
Several other research institutions are using the Phantom in conjunction with NIH's Visible Human Project to model endoscopic procedures. With a single probe connected to the Phantom, we can simulate not only the feel of the probe as it moves through a human body, but we are also able to attach a virtual fiber-optic scope to the end of the probe giving a simulated view on the computer screen. We also imagine palpitation exercises where the user could feel areas of the patient looking for clues as to what is wrong. As hardware, software and the accuracy of models improve we also foresee modeling techniques which call for cutting and stitching inside the patient.
To a surgeon, the process of using the Phantom essentially duplicates the process of surgery. (S)he uses the same instruments, views the same video monitor, receives the same feedback, and, most importantly, feels the same sensations from the probe.
With computer modeling, however, we can simulate broader ranges of procedures and complications than most students ever encounter in the normal course of their education. And we would be able to introduce certain surgical techniques to students (and practicing surgeons) who need to learn new procedures. We can model variations in patients which can affect surgical procedures: male and female, varying heights and weights, and conditions for palpitation exercises to give students a better idea for how things should feel under these varied human conditions.
We can also take real patient data from MRI's and do modeling based on that data, giving the surgeon an opportunity to both see and feel inside the patient before a surgical procedure even begins.
The NIH's Visible Human Project is one of the enabling technologies which allows us to use haptic devices to model human anatomical structures. The Visible Human Project took male and female cadavers, froze them, and generated cryosection coronal slices; the Visible Human Male consists of 26 gigabytes of data in 1,878 1-mm coronal slices and the Visible Human Female consists of 64 gigabytes of data in 5,180 0.3-mm coronal slices. Their data can be aligned to construct sagittal and transverse images of the Visible Humans. In addition, Gold Standard Multimedia has labeled the entire Visible Male data set, to a resolution of 0.3-mm with 1,200 distinct structures. With the labeled data, both comprehensive on-line atlases for medical school education and volumetric reconstruction of those structures in 3-D can be created relatively easily.
Over the past decade, computer-aided visualization has dramatically enhanced the study of molecular biology. Twenty years ago, structural biology was a hazy frontier traversed by a very small group of spatially gifted elite. Only a handful of scientists could interpret structural data, and only a few of those could translate the data into visual information. Today, using computer-aided visualization, a much wider audience of biologists and students can see and understand molecular structures. The non-obvious domain of molecular biology is now open to all biologists, biology students and even non-majors.
As helpful as the spatial visualization tools are, there are limits to the information they can portray. For instance, though many software packages have tried, none have been able to give an instructive visual picture of force. This is simply due to inherent limitations in three-dimensional representations. Just as a knowledge of spatial relationships is key for understanding what molecules are, an intuition of force is essential for understanding how molecules work. Though biologists are able to do dynamics simulations to see what molecules do over time, there is little intuition as to "why" they do what they do.
It is in this area that the Phantom is such a boon. Force cannot really be intuited through visual cognition, but can be "felt". The essence of computer-aided intuition is relating sub microscopic properties and events (which have no direct analog in human experience) to human perception. For spatial relations, vision is an obvious choice. Likewise, what better way is there to get a sense for force than to "feel" it? The human mind is not inherently analytical, but rather functions on intuition - deduction comes after the fact. By developing the Phantom to intuit forces, the field of molecular biology (and especially teaching) may well experience another dramatic leap on like that experienced with the advent of scientific visualization.
SensAble™ Technologies' Phantom and the Visible Human data sets provide an exciting opportunity and the University of Chicago is poised to take advantage of it. With our renowned faculty, BSDIS programmer experience, and the VISBL Lab, our state of the art computer visualization facility, we are uniquely situated to develop breakthrough software using the Phantom and Visible Human data. If you would like to discuss potential software development in these areas, please contact the CRT at crt@bio-3.bsd.uchicago.edu