Tag Archives: Kurt Kleiner

University of Toronto’s (Canada) smiley face tattoo/sensor

Researchers at the University of Toronto have created a medical sensor that can be applied to the skin like a temporary tattoo.

University of Toronto Scarborough student Vinci Hung helped create the smiley face sensor shown here in the box at upper right (photo by Ken Jones)

The Dec. 3, 2012 news item on ScienceDaily notes,

A medical sensor that attaches to the skin like a temporary tattoo could make it easier for doctors to detect metabolic problems in patients and for coaches to fine-tune athletes’ training routines. And the entire sensor comes in a thin, flexible package shaped like a smiley face.

“We wanted a design that could conceal the electrodes,” says Vinci Hung, a PhD candidate in the Department of Physical & Environmental Sciences at UTSC [University of Toronto Scarborough], who helped create the new sensor. “We also wanted to showcase the variety of designs that can be accomplished with this fabrication technique.”

The Dec. 3, 2012 University of Toronto news release by Kurt Kleiner, which originated the news item, provides details about how the sensor/tattoo is fabricated and how it functions on the skin,

The new tattoo-based solid-contact ion-selective electrode (ISE) is made using standard screen printing techniques and commercially available transfer tattoo paper, the same kind of paper that usually carries tattoos of Spiderman or Disney princesses. In the case of the smiley face sensor, the “eyes” function as the working and reference electrodes, and the “ears” are contacts to which a measurement device can connect.

The sensor Hung helped make can detect changes in the skin’s pH levels in response to metabolic stress from exertion. Similar devices, called ion-selective electrodes (ISEs), are already used by medical researchers and athletic trainers. They can give clues to underlying metabolic diseases such as Addison’s disease, or simply signal whether an athlete is fatigued or dehydrated during training. The devices are also useful in the cosmetics industry for monitoring skin secretions.

But existing devices can be bulky, or hard to keep adhered to sweating skin. The new tattoo-based sensor stayed in place during tests, and continued to work even when the people wearing them were exercising and sweating extensively. The tattoos were applied in a similar way to regular transfer tattoos, right down to using a paper towel soaked in warm water to remove the base paper.

To make the sensors, Hung and her colleagues used a standard screen printer to lay down consecutive layers of silver, carbon fibre-modified carbon and insulator inks, followed by electropolymerization of aniline to complete the sensing surface.

By using different sensing materials, the tattoos can also be modified to detect other components of sweat, such as sodium, potassium or magnesium, all of which are of potential interest to researchers in medicine and cosmetology.

You can find the reserchers’ article in the Royal Society’s Analyst journal,

Tattoo-based potentiometric ion-selective sensors for epidermal pH monitoring
Amay J. Bandodkar ,  Vinci W. S. Hung ,  Wenzhao Jia ,  Gabriela Valdés-Ramírez ,  Joshua R. Windmiller ,  Alexandra G. Martinez ,  Julian Ramírez ,  Garrett Chan ,  Kagan Kerman and Joseph Wang in Analyst, 2013,138, 123-128 DOI: 10.1039/C2AN36422K

The article is open access but you do need to register for a free account with the Royal Society’s RSC [ublishing platform.

Vampire batteries in Germany too?

I posted a very brief item (April 3, 2009) about some research being done at the University of British Columbia (UBC in Vancouver, Canada) on potential medical devices called ‘vampire batteries’, which use blood as fuel. The UBC team is not alone in its pursuit. A July 15, 2011 news item, Electricity from blood sugar, on Nanowerk, highlights similar research in Germany,

Implants that obtain their energy from blood sugar and oxygen: Dr. Sven Kerzenmacher at the Department of Microsystems Engineering (IMTEK) of the University of Freiburg is researching the development of biological fuel cells with the goal of finding an inexhaustible source of power in the human body. He has been awarded the 2011 FAM Research Prize for his dissertation by the Forum for Applied Microsystems Technology (FAM). …

Researchers have yet to find an optimal method for supplying implantable medical microsystems with electrical energy. The batteries of a pacemaker, for instance, need to be replaced after roughly eight years—meaning a strenuous and expensive surgical intervention for the patient. An alternative approach is to use rechargeable batteries. However, the necessity of recharging the batteries greatly reduces the patient’s quality of life. The idea behind Sven Kerzenmacher’s research, on the other hand, is the possibility of using implantable glucose fuel cells on the basis of noble metal catalysts like platinum. Such catalysts are particularly well suited for use in implant systems due to their long-term stability and the fact that they can be sterilized. In the future, systems equipped with these fuel cells could be supplied with power by way of a continuous electrochemical reaction between glucose and oxygen from the tissue fluid.

Here’s what the team at UBC was doing (from the April 1, 2009 New Scientist article by Kurt Kleiner,),

A team at the University of British Columbia in Vancouver, Canada, has created tiny microbial fuel cells by encapsulating yeast cells in a flexible capsule. They went on to show the fuel cells can generate power from a drop of human blood plasma.

There is no mention of clinical trials, human or otherwise in the news item about the work in Germany or at UBC, which makes it difficult to guess how close they are to using these fuel cells in patients but I imagine there are still several years of lab work ahead given this comment from Kleiner’s 2009 article about the UBC team’s work. A colleague at Cornell noted,

The work is a step in the right direction, but huge challenges remain, says Lars Angenent, who works on microbial fuel cells at Cornell University.

For instance, to keep the yeast cells healthy, their waste products will need to be removed without allowing any harmful substances to leach out into the blood stream.